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General Categories => Non Gun Stuff => Topic started by: unfy on September 13, 2015, 08:32:07 PM

Title: Aluminum melting
Post by: unfy on September 13, 2015, 08:32:07 PM
Sooooooo

I've got a garbage can full of root beer, pepsi, etc cans.  I had talked about the electric furnace a few times before... but that's kind of on hold due to situations etc.  I still wanna do things with it, but the full can is taking up too much room, maybe if I made some quick ingots...

Decided to go ahead and "build" this: (punching holes in coffee cans dont count as building...)

http://www.instructables.com/id/Build-a-foundry-and-sand-cast-aluminum/ (http://www.instructables.com/id/Build-a-foundry-and-sand-cast-aluminum/)

Built as described (see first pic).

Went through a bunch of cans, and I know cans aint much... but was starting to get a little more than curious / worried ... especially when the entire "crucible" (read: bean can) seemed to be filled with nothing but dross.

Took it apart and I found where all the aluminum went (see next two pics).

So, for a first attempt, I'd be willing to call it a 'partial success'.

I'll try again - with either not pressing down on the cats cans at all, or possibly using a 2" diameter black nipple as the crucible.



edited for typo
Title: Re: Aluminum melting
Post by: shooter on September 13, 2015, 10:09:02 PM
 how many cans did you melt? and ounces of good aluminum?

   I thought about using broken up transmissions?
Title: Re: Aluminum melting
Post by: unfy on September 13, 2015, 10:46:26 PM
How many cans ? No clue.  This was a first run and just trying to actually pour an ingot.

Didn't get there.

I have bean can (ok, soup can, whatever) that has probably a half inch or so of aluminum in the bottom of it, and then I have all that seeped out into the bottom of the air chamber coffee can.  I'll.... take a look at getting the aluminum out of the bottom of the coffee can in a bit since there's some questions.

Here's a fella that does a 55 gallon bag of crushed cans:

https://www.youtube.com/watch?v=nQzQEGZsEHw (https://www.youtube.com/watch?v=nQzQEGZsEHw)

He guesses at the end 50/50.  There are complaints in the comments, as expected.  The top comment suggests about a 30% loss instead.




This guy has a much larger setup, he melted the head of a car in a relatively short amount of time (25-30min?).

https://www.youtube.com/watch?v=CjDeGDn_fkI (https://www.youtube.com/watch?v=CjDeGDn_fkI)



It was interesting to do my first melt of something other than lead.  I'm sad that it didn't go as planned but it was still a learning experience.

A 2 inch diameter nipple doesn't really seem like an ideal crucible.   But the idea that it came from was this video:

https://www.youtube.com/watch?v=nPyRT7eQhu0 (https://www.youtube.com/watch?v=nPyRT7eQhu0)

Which seems to be a great video IMHO (and I have all the materials to build one of those if I wanted heh).

Anyway, 2" diameter means I'll have to fold each can as i put it into the crucible.  It also means that muffin tin ingots are out of the question.

I've got a Lee ingot mold for lead, I'll check if it's steel or not.  I'll also grab some 1-1/2 or something PVC to make some positives to push into sand (barring terminology).



I will LOL for a moment - the stuff in the bottom of the air chamber coffee can is so silly light when used to working with lead :).



Title: Re: Aluminum melting
Post by: unfy on September 13, 2015, 11:09:00 PM
Here's a couple more pics of the inside of the coffee can (below).

Seems to fluctuate a bit from 'none' to an inch and a quarter.  If I had to guess at average thickness, 3/4" or maybe 5/8".  It's a fair amount of fairly clean looking aluminum, which makes sense if it was leaking out of the bottom or side of the crucible.

I tried to gently hammer it out, but didn't have much luck without damaging the chamber too much.  Looks like I'll have to destroy the chamber to get it out :(.  I sadly don't have spare coffee cans lying around... and the 2 cans I used in this video were bought new (with coffee sitting in some bags in kitchen).  Guess I'll be buying yet MORE cheap coffee, sigh.

Oh!  Annnnd be aware - beer / soda cans aren't "just aluminum", they're an alloy.  Wiki says 92-97% aluminum. 
Title: Re: Aluminum melting
Post by: unfy on September 13, 2015, 11:23:51 PM
I guess it wouldn't be an unfy post without some talk about safety.

Don't use anything galvanized when working with melting aluminum.  You'll burn off the galvanization (zinc) which produces nasty fumes that will kill you.


This means no plated sheet metal, no plated hardware, don't use air ducting, anything that says the word zinc, etc. 

Coffee cans yes. Paint cans yes.  Food cans yes. Things that are 'weldable' yes.  Things that are 'stainless' yes.

I picked up the $40 respirator / air filter thing from hardware store.  Go ahead and buy the nicer ones that can block laquer and other things like that.  You ARE spending money for your own health here.  And I will gladly say that there was a huge difference in the smell of things etc after I took my mask off when investigating what was going on :) (so yes, it was doing its job wonderfully).  Also, it's nice to not get a lung full of hot air when the wind shifts or you're over the furnace.

Although I didn't feel it was fully necessary, I was wearing a welder's / leather bib.

As mentioned in the "instructable", don't stick your hot tongs down into the charcoal bag to grab another briquette to put into the fire chamber.  Them tongs are real hot and might ignite something.  I dumped out a bunch of briquettes onto the ground and just picked them up from there.  Was also easier instead of fumbling with them inside the bag (and means you didn't have possibly wet tongs near molten metal too).

All of my cans are dry but do be aware of the tinsel fairy and try to avoid it.

Although I had no spills, and such - the leaking crucible did mean I put a burnt circle in the grass.  This was unexpected and unfortunate.  Be aware and careful!
Title: Re: Aluminum melting
Post by: ILoveCats on September 13, 2015, 11:49:04 PM
Sorry if I missed this but...  What's the objective actually?  I mean other than just melting stuff.  Isn't it more cost effective to take the cans to Scrappy's to sell em for a few cents a pound?
Title: Re: Aluminum melting
Post by: unfy on September 14, 2015, 12:19:01 AM
Canpac here in Omaha looks to be $0.25 a pound, and the standard web coupon gets it to $0.30 a pound.

I might have ... 30lbs ? I dunno.  That's all of $9.

If it's 50/50, then 15lbs of ingots looks to go for about $50-$60 plus shipping (ebay, rotometals, etc).

addenum:

Ok, and lets add say $12 in charcoal to do all the melting (truly dunno how much I'll need, btw, this was a 2 bag guess).  Also get experience in the whole process and learn something new :D

As a cute side note - the first time I melted lead for making ingots, the pot I used burned through just like this crucible did hehe :P



Title: Re: Aluminum melting
Post by: Mali on September 14, 2015, 10:01:35 AM
Unfy,
I haven't had time to try this approach, but this video seems to make a pretty good crucible and foundry that would work better for you:
https://www.youtube.com/watch?v=hHD10DjxM1g (https://www.youtube.com/watch?v=hHD10DjxM1g)

The surprise of what he creates from the melted aluminum was so appropriate. ;)

The video for for actually melting the cans (10-12 cans/min) and creating aluminum ingots is here:
https://www.youtube.com/watch?v=lSoWxG30rb0 (https://www.youtube.com/watch?v=lSoWxG30rb0)

He found 38-45 cans creates 1lb of aluminum to be sold or used for casting.
Title: Re: Aluminum melting
Post by: Phantom on September 14, 2015, 02:32:46 PM
Is it just me ....or

when Unfy posts one of these and then talks about safety.  :o

Like me does everyone else look around for Minions ?   ;D
Title: Re: Aluminum melting
Post by: Mali on September 14, 2015, 03:48:23 PM
Is it just me ....or

when Unfy posts one of these and then talks about safety.  :o

Like me does everyone else look around for Minions ?   ;D
No, I agree. Unfy talking safety does make me wonder sometimes. :D
Title: Re: Aluminum melting
Post by: unfy on September 15, 2015, 12:45:26 AM
Unfy,
I haven't had time to try this approach, but this video seems to make a pretty good crucible and foundry that would work better for you:
https://www.youtube.com/watch?v=hHD10DjxM1g (https://www.youtube.com/watch?v=hHD10DjxM1g)

... snip ...

He found 38-45 cans creates 1lb of aluminum to be sold or used for casting.

38-45 cans seems about right going with the 30-50% loss number.

Fire extinguishers were on the list of possible crucibles.

Stainless cook wear is apparently on the list as well.

Car exhaust is another fine possibility that I've not dug into much (mostly due to how do I easily cap one end ?).

Fence posts are a no no (galvanized typically).

What I'll be trying next is one of the blue 14oz propane bottles for torches.  Make sure it's empty.  Remove the valve while it's underwater.  Make sure it gets filled with water so that there can be no gas in it etc.  Free to cut with grinder / hacksaw.

Why propane bottle ? I have one.  It should fit nicely in the fire chamber.  Should be big enough for soda cans.  It's not as thick walled as a black iron pipe nipple.   And looking at pictures, it's not as thick as a fire extinguisher either.  But - I have a spare propane bottle damnit :P.

The coffee cans as air chamber and fire chamber survived with no problems by the way.

A lot of this would be solved with a welder and stock metals, which I don't have access to.

Concerning furnaces & such - there are ALOT of videos out there.  There are ALOT of ideas.  The ideas about the different insulation is a mix of what they had available, what they wanted to try, and cost stuffs.  The different refactories also all have different service lifetimes (plaster of paris is on the shorter end of that list, by the way).

A charcoal base is cheap to build and cheap to fuel for quick one offs.  It produces the most ash, which then leads to the most dross / slag / whatever you wanna call it.  The amount of air movement also increases surface oxidation of the molten aluminum.

Propane torch + plaster or some other refactory can be built cheaply as well ($60 should get you something decent, $30 is prolly bare bones).  I will be building one of these eventually, just for the experience of it.  Also seems like less of a hassle than charcoal to use.  Oh, it's cleaner than charcoal (concerning crap in the aluminum etc).

Electric - initial heat / warm up takes longer.  There's not a huge amount of air flow so there's less oxidation.  Electricity is cheap.  The build is more complicated, and more costly as well.  You're tied to a generator or wall outlet.



Is it just me ....or

when Unfy posts one of these and then talks about safety.  :o

Like me does everyone else look around for Minions ?   ;D

No, I agree. Unfy talking safety does make me wonder sometimes. :D

Bite me, you two :P

I know y'all just giving me a hard time, but the insistence on safety is prolly why I can post here about some the weirder things I do :P



But, at any rate, after I get a few melts down (and there is no snow on the ground) - I'd be willing to show and tell with folks so they can try it out as well.

If I build something that takes a propane torch, I'll post about it as well.
Title: Re: Aluminum melting
Post by: unfy on September 15, 2015, 01:36:00 AM
Here's the crucible, and the bit of stuff that was in the bottom after cutting it out, etc.  There's still a little bit of steel on the puck on the sides.

The bottom didn't leak, but the sides blew out. 

The big obvious hole in the side you see in the first couple pics are from when I was actually hitting the side of if afterwards to just clean it up some. It acts just like a can that you recover from a campfire.

The bottom wasn't in too bad of shape compared to the rest of the can.

The puck I'll either keep as a momento or clean up the bit of steel that's still on the sides of it... and re-melt later.  It's a hefty little puck.  Dunno if that's a good thing or bad, but I swear I see plenty of good metal in it.
Title: Re: Aluminum melting
Post by: Mali on September 15, 2015, 07:48:36 AM
I know y'all just giving me a hard time, but the insistence on safety is prolly why I can post here about some the weirder things I do

And it is the reason I pay attention to what you talk about.  Experimenting is great as long as you can live to tell about it.

Some of the greatest disasters have started out with "Hey y'all watch this!" others with "Hold muh beer." :D
Title: Re: Aluminum melting
Post by: unfy on September 15, 2015, 09:22:23 PM
Cut up the air chamber to get out the glob of stuff in it.

1.41 pounds of relatively clean looking aluminum came out of the bottom of the coffee can.

See pictures.  Pencil for scale.


Title: Re: Aluminum melting
Post by: Mali on September 16, 2015, 12:15:52 PM
How heavy is it and how many cans did it take to get this?
Title: Re: Aluminum melting
Post by: Phantom on September 16, 2015, 01:31:39 PM
Quote from: Phantom on September 14, 2015, 02:32:46 PMIs it just me ....or when Unfy posts one of these and then talks about safety.  Like me does everyone else look around for Minions ?    Quote from: Mali on September 14, 2015, 03:48:23 PMNo, I agree. Unfy talking safety does make me wonder sometimes. Bite me, you two I know y'all just giving me a hard time, but the insistence on safety is prolly why I can post here about some the weirder things I do


It's a Dirty Job.........but someone has to poke you from time to time  :o :laugh:
Title: Re: Aluminum melting
Post by: unfy on September 19, 2015, 02:37:29 PM
It was time to try again.

Went to thrift store, picked up a couple steel / stainless things to make crucible out of.  Also cut a 14oz propane tank in half.

Went through two crucibles and they both had blow outs.

No, I'm not jabbing them with anything.

No, I didn't press the cans down into the pot.

I'm a bit at a loss.  I *might* try again tomorrow, I dunno.  Getting a bit discouraged as to what I am doing wrong.

addenum

Off to the hardware store to build the 'king of random' furnace.  Maybe the melts are taking too long which is causing problems.
Title: Re: Aluminum melting
Post by: Mali on September 19, 2015, 04:58:00 PM
Went through two crucibles and they both had blow outs.

No, I'm not jabbing them with anything.

No, I didn't press the cans down into the pot.

Perhaps the heat isn't high enough to quickly melt the metal so you are keeping it at heat for too long? Or maybe the crucibles are too thin for the heat you are using?
Title: Re: Aluminum melting
Post by: unfy on September 19, 2015, 05:50:53 PM
Perhaps the heat isn't high enough to quickly melt the metal so you are keeping it at heat for too long? Or maybe the crucibles are too thin for the heat you are using?


Too thin is a possibility, but I don't think so.  The bean can lasted a little while, the first crucible today lasted a good 45-50min.

But, 50min ... that's like, 2-3 times too long compared to videos, hence thinking that maybe it's too long / need to insulate / whatever.  With the crucible being in direct contact with the coals, they prolly take a lot of abuse, while the aluminum is slightly insulated.

Also, I never really got to the point of where cans would just disappear directly into the Al pile, even with a decently melted pot cleaned of dross, it was still kinda "meh".  So I'm really thinking a 'better' furnace would really help out a lot.



The King of Random / Plaster of Paris bucket furnace - he got all his parts from Home Depot btw :D

I had stopped at menards to pick up some stuff (it's by work, etc) ... the metal pail they have is 12qt not 10qt.  Went ahead and grabbed the pail, 1x12 black iron pipe nipple (it'll be directly in heat, so no galvanized plz), pvc & adapter, play sand, u-bolts.  Also nabbed a 3" pvc coupler for the lid hole (instead of drilling it, although I believe I have a 3" hole saw).  Didn't see any 2.5qt buckets. The Bellevue Menards also doesn't appear to carry the 25 lb bags of PoP.  Weird.  Site and App says they do, but it aint there.

Went to Home Depot in Papillion.  Wandered around a bit, found some buckety things, and noticed a 2.5qt blue bucket.  Kinda near it, found the 10qt steel pail and grabbed it as well (will return the 12qt). Wandered around some more, looking for PoP (and maybe 'fire clay').  Didn't have much luck, pulled up the App.  Stuck 'plaster of paris' into it, and clicked on the 25lb bag.

What were the other suggested items from the app ?

The 2.5qt bucket.
The 5qt wide mouth bucket.
4" U-bolts
Play Sand
etc

I actually started laughing in the store.

Papillion had 2 bags of PoP, I bought one. They didn't have the 5qt wide mouth bucket.  I'll just use some kind of substitute.

I am *really* tired (been up 20hrs or so)... gonna prolly just do the furnace build tomorrow while at work casting bullets and try aluminum again sometime throughout the week or next weekend.

I have a SS cup thing that is a bit on the skinny side of things but has a decent thickness, but it might work as a crucible.  A second thrift store hunt netted some pewter for lead alloy, but no other crucible possibilities.

I'll prolly also grab another bean / soup can as well.

Walmart did have an 18oz SS camping cup that was fairly wide mouthed but not very tall.



edited to fix some typos ... also, I appear to not have a 1-3/8 hole saw so will add that to my shopping list tomorrow
Title: Re: Aluminum melting
Post by: unfy on September 20, 2015, 02:00:09 PM
So.... the build has started, and has been taking far longer than expected... mostly because of me and not having the tool(s) I thought I did.

Anyway...

10qt pail, blue bucket.  Used sand as my filler, it was heavy enough it didn't try to float as much as video's did.

I did the 21/21/15 mix as suggested in King of Random's youtube video - but my play sand was already wet so.... I ended up adding some extra plaster to help thicken it a bit more / quicker.

The mix was in a 5 gal bucket to begin with, after I had all the chunks broken up and was mixing it for a bit, poured it into the 10qt pail.  It was taking a long time to begin to set, so I kept mixing it.  From a tactile view, this seems really important - continuing to mix it up until a bit before it's ready to set helps to keep the plaster / sand mixture more homogeneous.   Otherwise, the sand will just settle at the bottom.

The lid was a 10" plant / pot thing from garden section of menards.  Cost a buck.  The middle was ... I believe a 1 liter diet pepsi bottle.  The middle section of this bottle is 3" in diameter, making it good as a middle form.  Used some packing tape along the inside to tape it down (stop leaks, keep it in place, etc).  The bottle is flimsy, so heads up on shape.

I mixed this as 10/10/6.5 since the sand was already wet.  I ended up with about a half gallon left over.  I wonder if this means my lid isn't as thick as the videos or what.  Then again, my bucket is also fuller than the videos.  Shrug.  It set quicker due to less water, which is nice because mixing it in the bucket before pouring it into the form is easier than trying to keep it agitated in the form.  The nuts in the U bolts are holding the bars about in the middle of the plaster.  I tried to keep the u bolts lifted so the bare metal wasn't exposed on the bottom of the lid.  We'll see how well I did after a while :).

It's about time to remove the bucket and maybe drill the hole.



addenum: the pepsi bottle was used instead of the 3" coupling because the coupling has an OD of like 4".
Title: Re: Aluminum melting
Post by: unfy on September 20, 2015, 02:44:54 PM
Removed the bucket after 90min.  Used a hand shovel to dig the sand out first heh.

The blue bucket did not survive the twisting action as seen in the video.  Consider that a $3 consumable during the build.

Finish is indeed nice inside.

Decided to have my pipe approach the fire chamber at an angle so as to 'get a swirl'.  Supposed to more evenly heat things etc.

Sadly, I don't think I got the angle of my hole steep enough.  I tried re drilling it slightly, but I dunno if that was a good or bad thing. 

It had been about 1:45 - 2 hours since it had set.  The action of the hole saw meant that whatever was inside the saw re-liquified heh, but the hole is indeed keeping it's shape.

If I were to try this again, it would only cost another $6 or so.  The steel pail - just use some tape or something to cover the hole.  Have plenty of plaster left.  Might just have to buy sand a new blue bucket.  I should get dimensions on that bucket so that other forms can be built.... I'll edit this post in a bit to have measurements.

6-1/4" x 6" , tapering a bit towards the base.  For reference: a coffee can is 6" x 6".  You can't use a coffee can straight up, though - the ridges will make it impossible to remove without damaging the refactory.
Title: Re: Aluminum melting
Post by: unfy on September 20, 2015, 07:16:54 PM
Been casting bullets while the furnace continues to cure all afternoon (dunno why casting bullets is so relaxing, but whatever).  Second bar of shooter lead is melting into pot, so got a few min.  oi, skeeters out in force. not gonna get into next bar

It still seems quite plaster-of-paris fragile.  Still *feels* damp (or maybe just really smooth).  No, I don't have any metal showing on the base of the lid :D.

Put the lid on just to get a pic.  Drew a line around the base as well, just to see how much overlap there is between base and lid.  I'm not real happy about the results, but whatever (for now).
Concerning coffee can stuff -- if you drill a hole in the coffee can where you want the air inlet to be... wait.... that won't work.  Basically, I was aiming for:

* break out old refactory from pail
* install coffee can
* install pipe between the two holes
* re-fill plaster/sand refactory
* leave coffee can in there

Consider the coffee can a consumable and just something to help the inner lining of the refactory last longer.  Cure time would be longer, but whatever.

The problem ? would need a way to seal off around both ends of the pipe so that plaster doesn't leak into the coffee can, nor does it leak out the inlet hole.  Some kind of cardboard thing would prolly work.  Could also then just let the coffee can side burn away during first firing... and ... who cares about the outside one ?



Skeeters are gettin pretty bad, dunno if I'll finish off this next bar of lead or not ._.
Title: Re: Aluminum melting
Post by: DenmanShooter on September 21, 2015, 07:51:52 PM
Not really sure what purpose is for melting aluminum since you've already spent more than you'll ever get out of it I THINK.. but keep it up!!  This is interesting.
Title: Re: Aluminum melting
Post by: Mali on September 22, 2015, 09:21:47 AM
A this point I am interested in what works best and the effort to build the "best" one.  This is a VERY interesting project he has going.
Title: Re: Aluminum melting
Post by: unfy on September 22, 2015, 10:26:34 AM
Not really sure what purpose is for melting aluminum since you've already spent more than you'll ever get out of it I THINK.. but keep it up!!  This is interesting.

10qt pail: $9.88 (i don't recall it being that expensive, and it's re-usable):
http://www.homedepot.com/p/Behrens-10-Qt-Galvanized-Pail-1210GS/100125409?keyword=10+quart+pail (http://www.homedepot.com/p/Behrens-10-Qt-Galvanized-Pail-1210GS/100125409?keyword=10+quart+pail)

Plaster of Paris 25lb: $10.98 (have lots of left over)
http://www.homedepot.com/p/DAP-25-lb-White-Plaster-of-Paris-Dry-Mix-10312/100123682 (http://www.homedepot.com/p/DAP-25-lb-White-Plaster-of-Paris-Dry-Mix-10312/100123682)

4" U bolts: $1.06 ea ($2.12 total, and re-usable)
http://www.homedepot.com/p/National-Hardware-146-1-4-in-x-1-3-8-in-x-4-in-Zinc-Plated-U-Bolt-with-Plate-and-Hex-Nut-2190BC-146-U-BOLT-ZN/204591316 (http://www.homedepot.com/p/National-Hardware-146-1-4-in-x-1-3-8-in-x-4-in-Zinc-Plated-U-Bolt-with-Plate-and-Hex-Nut-2190BC-146-U-BOLT-ZN/204591316)

2.5qt blue pail bucket (destroyed, might be better to coffee can anyway? dunno?): $2.35
http://www.homedepot.com/p/Unbranded-2-1-2-Qt-Blue-Pail-with-Handle-0255030/204694319?MERCH=REC-_-PIPHorizontal1_rr-_-204078629-_-204694319-_-N (http://www.homedepot.com/p/Unbranded-2-1-2-Qt-Blue-Pail-with-Handle-0255030/204694319?MERCH=REC-_-PIPHorizontal1_rr-_-204078629-_-204694319-_-N)

1" black iron pipe 12" nipple: $4.59 (reusable)
https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/fittings/black-fittings/1-x-12-black-nipple/p-1389966-c-9501.htm?tid=-2734533308059917106 (https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/fittings/black-fittings/1-x-12-black-nipple/p-1389966-c-9501.htm?tid=-2734533308059917106)

Play sand: $2.80 (i actually got mine at menards, about same price diff brand, didn't quite use all of it)
http://www.homedepot.com/p/Quikrete-50-lb-Play-Sand-111351/100318476 (http://www.homedepot.com/p/Quikrete-50-lb-Play-Sand-111351/100318476)

1" PVC coupling: $0.90 (i dunno if this is the exact item, but price is close... dunno if this will melt or not heh)
https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/fittings/pvc-fittings/pvc-schedule-40-fittings/1-sch40-coupling/p-1752437-c-9384.htm?tid=1417075065774399578 (https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/fittings/pvc-fittings/pvc-schedule-40-fittings/1-sch40-coupling/p-1752437-c-9384.htm?tid=1417075065774399578)

1" PVC pipe, 5 feet: $2.00 (re-usable)
https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/pipe/pvc-pipe/schedule-40-solid-core-plain-end-pipe-1x5/p-2204484-c-19656.htm?tid=8576585851811028382 (https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/pipe/pvc-pipe/schedule-40-solid-core-plain-end-pipe-1x5/p-2204484-c-19656.htm?tid=8576585851811028382)

I don't have a link to it, but the plastic flower pot tray that I used as a form for the lid was $1.00.  If you used a bucket, it wouldn't be a consumable.

Then above: $36.62

Add a crucible (still working on that....).

3/16" weldable steel rod (crucible tongs): $2.39 (reusable)
https://www.menards.com/main/tools-hardware/household-hardware/stock-metal/weldable-steel-round-rod-cold-rolled-3-16-x-3-ft/p-1466260-c-9215.htm?tid=6450838868653760237 (https://www.menards.com/main/tools-hardware/household-hardware/stock-metal/weldable-steel-round-rod-cold-rolled-3-16-x-3-ft/p-1466260-c-9215.htm?tid=6450838868653760237)

1/8" x 1" x 4 feet flat stock (dross removal tool): $6.99 (this can prolly be shorter or just not used, reusable)
https://www.menards.com/main/tools-hardware/household-hardware/stock-metal/weldable-steel-flat-1-8-x-1-1-4-x-4-ft/p-1466272-c-9215.htm?tid=-757372524152876331 (https://www.menards.com/main/tools-hardware/household-hardware/stock-metal/weldable-steel-flat-1-8-x-1-1-4-x-4-ft/p-1466272-c-9215.htm?tid=-757372524152876331)

Stainless steel spoon from walmart, about $2.00 (dross/slag).

Sooo... $11 or so in other tools ?

Oh, I did buy a hair dryer brand new from walmart for $9.99 or something.  Thrift store hair dryer prolly work just fine (want to push cold air, btw).

$55ish so far (not including failed crucibles or the initial coffee cans).  This includes a lot of stuff that is reusable.

I've also gone through 3/4 of a bag of charcoal - $6.

I'm not too sure about a hair dryer being taped to a pvc pipe in the middle of the air.  The King of Random video uses a 2 foot section of PVC.  I'm willing to bet a 6" section is enough (assuming it's out of the way).  Although, at 2 feet - the hair dryer is prolly far enough way to not accidentally pull in any hot exhaust of the furnace.

I've got prolly 2.5 - 2.75 lb of aluminum "globs".  I still have 85% or so of the garbage can to go through of crushed cans.

Assuming I get 15lbs of aluminum, I'll prolly break even or possibly be in the hole a bit.  At 20lbs I'm prolly ahead of the game.

Not to mention all the learning going on heh.

I have plans in the future of doing cast metal parts for stuff.  Lacking milling and lathes and stuff, prolly nothing anything too fancy - but, there are some things I wanna do that kinda want metal parts.

A this point I am interested in what works best and the effort to build the "best" one.  This is a VERY interesting project he has going.

"working best" ? that's all about a balance of cost prolly.

Did two empty coffee cans with some strategically placed holes, a bean can, a hair dryer, and some charcoal melt cans ? Yup.  Was it terribly useful ? Nope.

A hard firebrick inner chamber will withstand a lot of abuse.  Use of propane instead of charcoal will produce a cleaner molten pot and possibly be easier.  Maybe cheaper to use as well, I dunno.  Use of a better refactory (see also: perlite + high temperature bonding agent) prolly also far better than just plaster + sand... but perlite + bonding agent can't really withstand a lot of abrasion abuse.  Electric has longer warm up times, but less fumes and a cleaner melt.  Prolly also cheapest to operate (but hardest to build).

If I can get a dozen melts out of the plaster bucket, then yay.  If adding the coffee can as part of the inner lining increases number of melts and possibly makes the build easier, yay. 



Today I'm gonna grab one of the failed crucibles.  Throw a few pieces of charcoal in the crucible.  Light it and put it into the furnace, and see if the heat helps to slowly cure things a bit more / etc.  I have no idea if it's fully cured or not, prolly is.  But a slow heating should be helpful, I would think.

I did grab some metal stuff from a few places to throw at a coworker with a welder to see if he can make me a crucible.  Sadly, I think it's only 16ga metal... but... it was cheap.  16ga appears to match the propane bottles, btw.


Title: Re: Aluminum melting
Post by: unfy on September 22, 2015, 04:51:23 PM
Piece of printer paper with some olive oil as kindling / tinder, 3 charcoal briquettes.  Cover with lid.  Block lid hole 75%.

3 hours later, do it again.

Metal pail is warm to the touch.  Plaster is changing color slightly.

Starting to look like rain, so set lid aside on some concrete and dumped out what was left of the last 3 charcoal pieces.  When I lifted lid to put it back on to furnace, there was a water mark disc on the ground.  Soooo yeah, the heat is definitely helping to drive out more moisture.  And is something I would suggest for other builders (although for plaster of paris, I dunno how required it might be).



This is just a bit of explanation, feel free to ignore it.

With normal refactory / furnace stuff, you slowly bake everything to drive out moisture very very slowly.  As time goes on, you increase the heat to drive out even more moisture and other related stuffs.  With the electric furnaces, the cook time is up to a week!  By slowly driving out all the moisture, you avoid micro steam explosions that can cause cracks in the refactory (or far worse).  And yes, at 1000-2000f - there is a lot more water in a rock / brick you might think heh.
Title: Re: Aluminum melting
Post by: shooter on September 22, 2015, 05:27:43 PM
 Im not sure about plaster . but you never heat cement. the water inside it will expand and explode, ive seen pictures of fireplaces that weren't allowed to cure, and they blew chunks into the next wall.
Title: Re: Aluminum melting
Post by: unfy on September 22, 2015, 06:04:12 PM
Im not sure about plaster . but you never heat cement. the water inside it will expand and explode, ive seen pictures of fireplaces that weren't allowed to cure, and they blew chunks into the next wall.

Indeed!  And most sources will give similar warnings.  Also reminds me of boy scouts / don't use river rocks for camp fires.

Also, even when using a "proper refactory mix", everyone warns about long cure times and slow heating to avoid explosions :).

So far, heating plaster of paris very slowly seems to be driving out moisture.

http://www.backyardmetalcasting.com/refractories.html (http://www.backyardmetalcasting.com/refractories.html)

The above discusses using portland cement with other things.

http://www.imarketingcenter.com/refractory.html (http://www.imarketingcenter.com/refractory.html)

Has some other stuff, but also mentions slow firing.

http://makezine.com/2012/04/05/how-tohomemade-castable-refractories/ (http://makezine.com/2012/04/05/how-tohomemade-castable-refractories/)

This shows 1 part premixed refactory cement to 4 parts perlite.  I think that's the ratio anyway.  This is similar to the mix mentioned in Gingerly's electric furnace (and maybe Dan Hartman's).

http://www.iforgeiron.com/topic/3392-homemade-refractory-recipe/ (http://www.iforgeiron.com/topic/3392-homemade-refractory-recipe/)

Has... well... a bunch of stuff.  Dunno how much to trust the responses, and given the name of the site... if they're going for iron instead of aluminum... that is a large heat difference.  They claim portland won't hold up.  But... again, if going for iron melting temps, then maybe not.


Title: Re: Aluminum melting
Post by: Mali on September 23, 2015, 08:16:03 AM
More good info I was not aware of, thank you.
With that knowledge I would say that leaving the PoP refractory outside would be bad since it will most likely get water back, correct?
Title: Re: Aluminum melting
Post by: unfy on September 23, 2015, 10:50:38 AM
I have no clue how pop works.

I know that it likes water, then it rejects water.  What happens after that, I dunno.

IE: you can mix PoP in a bucket.  Eventually it'll set, possibly leaving water on top.  If not, you can dump more water on top and it will *still* cure while the water remains clear.  I think, though, that if you can mill it / grind it up, it's reusable ? Maybe ? I dunno.

PoP isn't really something I've messed with much (it's typically too fragile for anything I'd want).

There's probably a protocol for dealing with furnaces that are exposed to humidity.  Something like "if it hasnt been fired in X time, do a slow firing for Y min before doing a full blast melt".  But, I have NO clue.  NONE.

It could also be that as long as you don't throw water on most types of cured refactory, they won't absorb water (ie: the won't suck it out of the air).

In other news - the slight sprinkles (cough) we're getting here in the Omaha area kinda makes continued slow firing difficult.
Title: Re: Aluminum melting
Post by: unfy on September 23, 2015, 12:11:52 PM
https://www.youtube.com/watch?v=Acx1Wu9k8Ac (https://www.youtube.com/watch?v=Acx1Wu9k8Ac)

This looks to be just straight PoP... and it didn't work at all heh.

There's a few other furnaces that use PoP/sand on youtube. 

There was a PoP mold brass video thing as well.... uhhhhh.... I don't have the link handy at the moment.  Anyway, melts the brass in a furnace and them pours into what looks like pure PoP 'bowl' (that is, bowl shaped).  As you would expect, the mold cracked.  No leaks or anything too dangerous looking - but in all fairness, that's an abusive thermal shock.
Title: Re: Aluminum melting
Post by: Mali on September 23, 2015, 01:04:49 PM
There was a PoP mold brass video thing as well.... uhhhhh.... I don't have the link handy at the moment.  Anyway, melts the brass in a furnace and them pours into what looks like pure PoP 'bowl' (that is, bowl shaped).  As you would expect, the mold cracked.  No leaks or anything too dangerous looking - but in all fairness, that's an abusive thermal shock.
This video?
https://www.youtube.com/watch?v=U2_F9-oQiQA (https://www.youtube.com/watch?v=U2_F9-oQiQA)
So much time to just prove that you should burn out the moisture first. :D
Title: Re: Aluminum melting
Post by: unfy on September 24, 2015, 08:27:45 AM
This video?
https://www.youtube.com/watch?v=U2_F9-oQiQA (https://www.youtube.com/watch?v=U2_F9-oQiQA)
So much time to just prove that you should burn out the moisture first. :D


That's the video :D

I dunno if the point was to show that it needed to be baked, or if just to show it can be done.  The description feels ambiguous in that regard.

I'd prolly suggest just green sand or petrobond anyway.  It's reusable etc :D.

Hoping the weather clears up, wanna continue the slow bake of furnace.  Coworker may or may not have me some crucibles made from exhaust pipe, too.



Title: Re: Aluminum melting (nothing new)
Post by: unfy on September 25, 2015, 06:16:43 PM
No real update yet... rain etc.

Been continuing to slow fire the thing today for the last few hours.

Took lid off to add more charcoal, figure'd I'd take a picture of the moisture ring left over after lifting the lid back up.

I should be attempting another melt this weekend.
Title: Re: Aluminum melting (progress and pics)
Post by: unfy on September 26, 2015, 06:23:07 PM
Did 3 pours today.

Was heating fourth and crucible failed.

This crucible was some exhaust pipe with some flat stock / plate welded on the bottom. I do not have any before / after pictures of the crucible as of yet.

The first two pours were from 50 and 52 cans respectively. I got 0.85 pounds of aluminum out of each (so 1.70 pounds of aluminum from 100 cans). 

This is far worse than what other people were getting.  I suspect that I'm need to run things hotter so that I lose less when cleaning off the dross / slag.

I have noted that crushed cans appear to be worse for this set up.  Uncrushed cans go in much cleaner and easier, etc.

In the two pics below, I have a little rock or something holding up one side of the lid.  With some charcoal under the crucible, the 1" of clearance between the lid and the crucible disappears, so I needed some room for exhaust.

The pours are ugly.  The holes for the U shaped grabber is great, but having an easier / better way to tilt the thing would be great.  Also, by the time I was 1/3rd way through the pour, things were getting hot, so started to rush / panic a bit.  I do have solutions for both of these.

I recommend after each pour to dump the charcoal and dust out of the furnace and then replace the big chunks of charcoal and cover with new stuff.  All of the ash will eventually compact and just make cold areas etc due to no circulation.  Also, the amount of ash flying into the crucible will become unacceptable.

The plaster/sand refactory is very spider webbed after 5 hours of melting stuff.  There's also gonna be a glob of aluminum in the bottom of the fire chamber heh.  But, it has held up surprisingly well.

I'm gonna go cast a bunch of bullets now - will possibly add more thoughts later tonight or something.

Title: Re: Aluminum melting
Post by: shooter on September 26, 2015, 06:29:58 PM
 if you need a thicker pot, come on out, we can dig thu the iron pile and find you something, maybe a piece 1/4 inch thick?
Title: Re: Aluminum melting (pics of furnace afterwards)
Post by: unfy on September 26, 2015, 09:09:39 PM
Here's the furnace after all was said and done and cooled.

Quite cracked / spider webbed - as I expected.  It looks fairly decent (compared to my expectations) - although the section above the air inlet hole is questionable.

Also shown is the lid.

Lid has some cracks, makes me a bit uneasy, but it seems to be "okay".

As an aside, both the furnace and the lid lost a lot of weight (i'll assume the water cook off).

Title: Re: Aluminum melting
Post by: unfy on September 26, 2015, 09:21:03 PM
Sadly, I've got six pics of the crucible, so this will require two posts.

Anyway, hit it with a brass brush afterwards to clean it up a bit to more easily spot stuff.

I think there were multiple failures.

First pic shows one of the the larger in size failure.

Second one shows the other one.

Third pic is the bottom.  I dunno if the bottom actually failed or not.  Sure, you see a bright spot - but the crucible was most likely floating on top of molten aluminum in the furnace.  There was also some stuck to some sheet metal I had placed the crucible on after recovering it.

The fourth pick shows the inside.  I have thrown a few other scrap bits of slag / spare aluminum in it.  The shiny piece towards the middle standing up tall is what was in the side of the crucible after a pour (and I pulled away from the wall after things had cooled).

Top of the crucible looks great.  Seam of the pipe looks great, too.



Title: Re: Aluminum melting (last 2 crucible pics)
Post by: unfy on September 26, 2015, 09:30:05 PM
Last two.

In the first pic, I have an arrow pointing to a blob.  I'm not sure if it's a weld failure or not.  I'll need to do some stronger brushing and stuff tomorrow.

Second pic is to kinda show both know failures and to also point out that they're about 90 deg out from the lifting holes.  I'll also remind you that one of the lifting holes goes through the pipe seam... so it's related to that.

Anyway... to my point, kinda.

I would have my _| |_ looking rod thing for lifting the crucible.  Works fine, I think I wanna add some extra bends in the rod to aid in pouring (more in that in a bit).  But in order to tilt the crucible, I've been kinda grabbing it with the grill tongs to lift the ass end.

Maybe I'm squeezing (too hard) on the tongs as I try to lift the ass end of the crucible ?

Maybe the saw tooth teeth of the tongs is cutting into the crucible ?

I put a conscious effort into not squeezing the crucible as I try to do the pour, but as I mentioned in a previous post, I do get a bit rushed / feel the heat.

Title: Re: Aluminum melting
Post by: unfy on September 26, 2015, 09:31:42 PM
if you need a thicker pot, come on out, we can dig thu the iron pile and find you something, maybe a piece 1/4 inch thick?

See, that kind of offer is hard to turn down.

I will definitely keep it in mind and will most likely take you up on it heh.

Out of curiosity, are ya gonna make it to the Gretna breakfast, shooter ?



Oh yeah, I did burn through probably 12-14 pounds of charcoal today (in 4 melts).
Title: Re: Aluminum melting
Post by: unfy on September 26, 2015, 10:46:40 PM
Crucible tongs / rod thing.

The concept was based off of the paint can furnace video I linked on first page.  I've seen videos of other folks who use eye bolts and try to hook rod hooks through the eyebolts - but that never seemed all that great to me.  Even in one of the videos, the guy only hooks one of the eyelets while on the other one the rod is hooked under *under* it and slips out later.

First pic is pretty much what I got now.  I don't have the lower eyelet for hooking to lift the ass up to pour... but that's not the point.

The second pic is the same, but I horrendously drew on a suggestion of the bends I've talked about.  With hooking from the inside of the crucible - if you attempt to tilt the crucible on the holder thing, you bump into the edge of crucible with the long straight part of the rod.  I assume with the bends suggested, you wouldn't have to tilt the holder rod so far forward during a pour.  Kinda needs more pics to explain, but.... maybe you get the idea.



Since I've gone through a few crucibles, perhaps time to discuss dross / detecting failed crucibles.  Aluminum dross is far different than lead, mostly due to how light Al is and how rigid it cools to.

With the soda can source, the dross is fairly light, kinda 'burnt/expended wood' in a way.  The Al doesn't necessarily just "fall through it" like lead does It will try to, but it's weight makes it not as forceful about it.

Due to the heat, it's got a weird texture, too.  Kinda like a rubbery muffin.  Or bread maybe.  It's very light, very sproingy too.

When there's a huge blob of it down inside the crucible surrounded by molten Al and you're using spoon or something to get stuff out - it's got a very jello like look & feel.

When a crucible has failed, you've basically got a pot full of really hot dross.  It kinda acts like the jello.  When you try to press into it with spoon or whatever - it kinda acts like a wet stack of card board or a wet phone book.  There's not a whole lot of give like there would be if it was floating on top of Al.  Nor do you feel it kinda breaking up as you make it " V " as ya press into it (if it was in Al, that is).

Obviously there not being as much in the crucible as you think there ought to be is a no brainer :)

Al dross / flakes are quite sharp and can be surprisingly rigid.  Just something to think about.



Lastly, and off topic.  An ex-coworker came by, and we've both noted the smell of pineapple when melting cans.  The sugar, maybe ?  The cans in question are all soda cans.  Pepsi, no name 'cola', and rootbeer.

I'll re-iterate that this furnace / crucible setup really prefers uncrushed cans.
Title: Re: Aluminum melting
Post by: unfy on September 28, 2015, 06:37:05 PM
A second look at the crucible while explaining stuff to coworkers (who are interested as well)...  we were all in agreement the failure was exacerbated by how I was grabbing the crucible with grill tongs etc.  We'll work out a new system before the next melt.

The furnace and lid are very empty sounding.  Kinda like old bread heh.  And no, they don't have the 'earthen crucible' ringing sound to them.

I dunno if I posted this before or not, but the off center air inlet pipe really worked out well.  It was definitely whipping the flames around the crucible with that 'swirl' folks talk about.  So that's a huge suggestion / plus / change from the video.  While other builds all suggest it, having actually seen it in action, I concur even with charcoal as a fuel source.

Heads up about the air gap.  I was originally using a tiny blob of aluminum to hold the lid off the furnace for air movement.  It melted heh.

And about the handles on the lid.  It's obvious, but yeah - they get f'in hot!  Everything was cooling for like 30-45min and the U bolts still burnt me when I tapped them.

Title: Re: Aluminum melting
Post by: unfy on October 03, 2015, 02:54:45 PM
Sadly, the two crucibles from coworker won't work.  He was in a rush... they don't even hold water.

I dunno if I'll attempt stuff Sunday or not.



In other news, was looking at the furnace and lid.

Lid's cracks seemed to have gotten worse.  It also had a "feel" between pound cake and angel food cake.  Decided to flex it gently just to see if I should even remotely trust it or not.

It crumbled heh.  (first pic).

Looking at the pieces, there was a color difference between really hot and not hot areas.  See the second pic.  I post processed the picture just a tad to increase the color saturation a bit (the color difference is more pronounced than original picture showed).

Ran to menards, grabbed another plastic pot pan thing, and mixed up a new lid at 10PM heh. (last pic)


Title: Re: Aluminum melting
Post by: unfy on October 03, 2015, 02:59:45 PM
Oh yeah.

Picked up some fire place tongs, a couple flat furniture braces (to run bolts through to make a stop point so i can't crush crucibles).

Also grabbed a 50lb bag of 'resco goldart' clay from the paint / ceramics place near 84th/78th and Harrison in La Vista.  It was $20.  It's prolly not quite what I want, but it'll do for experimenting probably. 

As far as "what it can do", this seems to be a relevant page:

http://digitalfire.com/4sight/material/goldart_198.html (http://digitalfire.com/4sight/material/goldart_198.html)

The above has an boogie woogie amount of cursory information about a lot of clays.  I'd suggest a bookmark.

Title: Re: Aluminum melting
Post by: unfy on October 17, 2015, 05:31:27 PM
Coworker redid the two crucibles.

Melting today.

Eyelets help a lot for control and stuff.

Not keeping count for can turn over etc.

Just a quick pic :).
Title: Re: Aluminum melting
Post by: unfy on October 17, 2015, 06:55:16 PM
Welp... next melt after the pic had a blow out.  I really should start to go with my gut feeling on if the crucible is fine or not. 

Everything is cooling down atm.  I'll note that after I decided the crucible was failed - poured out the contents into 2 mini muffins.  Started picking charcoal out of the furnace.  Even after 10min of killing the oxygen and leaving it open and having removed a bunch of charcoal, the AL inside was still molten.  Which means as a furnace material, the PoP and sand is doing okay for AL.  Oh, and the mini muffins were glowing red / stayed molten for a long time too.  Soooo yeah, that thing was hot.

Will wire brush and take more pics later... but an initial glance seems to show a hole opposite of the eyelet in the wall of the crucible.

Taking shooter up on his offer to look for a crucible seems to be the logical next step.  Might look on ebay for chinese crucibles / tongs as well.

Will also eye ball propane furnace builds with more proper clay etc.  Charcoal has been great as experimentation, but I'd like to move on to something cleaner as well as easier. add: consistent

Some other thoughts: did the charcoal get way too hot ?  I know folks say propane gets hotter, but when it's "gettin it", charcoal seems to really be abusive heh.  I have done some "gently scrape the sides with stainless steel spoon" stuff as part of getting rid of dross/slag.  Is it possible that I'm taking crucible material with it when I do this ?  I know steel crucibles will flake with AL temps and contaminate the AL - is it possible that even though I'm not putting any pressure on the wall when doing my scrape, that I'm making it worse ?

To repeat last post: eyelet is ****ing awesome for pouring etc.

To repeat a comment earilier: the offset air tube for swirl flame action is awesome.



I'll be doing more tomorrow.

Even though you're wearing welding gloves, be aware that if you cook them, they'll get hard / rigid.  Especially at the seams.  I've now cooked 1.5 "right hand" gloves heh.



First pic below shows a crack that has developed in this 'new second lid'.   Everything seems fine, though.  Not entire sure what that thing line originating from the bottom is.  I'll eye ball things more later.  Lastly - the U bolts have started do discolor.  Different gloves ? heat ? I dunno.

Second pic shows the crack as well , but more importantly a peak down into the chamber.  There's a jet of slightly yellow flame roaring out the vent hole that you can't really see.  The "laser" looking things would be flying embers.  The crucible was probably already failed in this pic, btw.

edit: forgot to attach pics
Title: Re: Aluminum melting
Post by: unfy on October 18, 2015, 07:37:11 PM
Been melting more today.

The changes:

* well, the lid broke cleanly in half when i lifted it this afternoon before getting started.  since it's a clean break with no other cracks, i'm still using it.

* using a chunk of fire brick as a plinth beneath the crucible (score and break kinda like glass or plexi ... it does but doesnt work lol)

* when removing dross / slag, i'm only digging straight down into the crucible, avoiding the sides.

* on my second melt, I just kept adding cans, letting them stack without caring too much.  did one clean and then just stacking them again.  furnace and crucible all had that nice red glow so i just kept stacking.  I'd gently push the cans down into the crucible to keep making room.  Particularly, i'd try to take my crushed cans in a <> shape and push them spikey end down.  Avoids the wall and I can stop before getting too far down.  Towards the end, a nice pool of AL was formed and I was able to more or less just push cans into the pool repeatedly (much like dealing with molten lead and feeding small ingots).

* dumping the second melt, there was a whole bunch of crud at the bottom of the crucible ... on the reheat i'll clean it up a little bit, but not much.

Pics later.
Title: Re: Aluminum melting
Post by: shooter on October 18, 2015, 11:34:31 PM
 it sounds like you are taking what you are using for a pot out and pouring it into the molds, ever think of using a ladle and dipping it out? I would think that disturbing everything to take it out might be hard on stuff
Title: Re: Aluminum melting
Post by: unfy on October 19, 2015, 08:37:25 PM
I don't doubt that the thermal changes are prolly causing problems.

Using a ladle is probably not really gonna work.  While lead has a high specific heat / density - aluminum cools so quickly that it's just not likely to really work.  That said, does the stainless spoon I use end up glowing red ? Yes.  The little bit of flat stock I use for poking / skimming ? Yes.  Could heating the ladle to red hot possibly help ? Maybe.  I really don't care to try to ladle 1400F liquid, though.

Coworker wants to try slitting the exhaust pipe down the middle and wrapping it around another section of pipe.  I dunno if it's really gonna help, but it might... so why not.

Charcoal touching the crucible probably aint helping.  Using really dirty / crummy cans probably aint helping.  The slag/dross/whatever-the-****-its-called does like to create a jellied sponge like material.  This will stick to itself and to the crucible walls.  Who knows how many layers of crucible flakes off with it when you break it off a little bit etc.



Don't have much on pics.  Just gonna show the cracked lid after it was used.  I'll make another lid some time this week.  I'll include some wire mesh this time to see if it helps with strength.

Crucible failure was along the walls again.

Using a plinth seems to have really helped.  The stable base for the crucible while the charcoal crumbles is alright.  Due to the refactory and such of the furnace - there's also not a concern about applying direct heat to the bottom of the crucible like the double coffee can furnace.  This also means the base of the crucible isn't necessarily swimming in charcoal dust as time drags on.  The stable base means it aint leaning to one side and all of that jazz.

After each melt, you really wanna take the big burning chunks of charcoal out (and save) and dump all the dust / sand charcoal.  Then repopulate the furnace with old hot charcoal and throw more on top of it.  Billows / air powered charcoal does burn quickly :).

Expect a 'normal large' bag of charcoal to last 2, maybe 3 melts.  At least, when doing cans.



So far, doing cans has been interesting as a learning experience.  I really don't suggest doing it as a full time source of AL though.  It's so dirty... such a hassle, etc.

Oh, Sunday's melts yielded a little over 2.5lbs of aluminum, including the puddle recovered from the bottom of the furnace after failure.



I've got almost everything to build a rammed up / harder furnace.  As in something for propane usage.  Gonna double check some dimension suggestions and buy some air ducting for the outside shell.  Yes, air ducting as a crucible or anything inside the furnace is bad because of zinc fumes, but with enough refactory the outside doesn't get that hot.

When I do that build, I'll keep pictures posted here.

Charcoal has been great as a 'get your toes wet', but I'm ready to move on.  So yes, I do suggest the pail furnace as a first go.



That lid picture ... actually... it won't let me upload it.  Or ... will it ? Forum is hating me atm...



Title: Re: Aluminum melting
Post by: unfy on April 01, 2016, 10:39:51 AM
It'll be time to try this again. 

I've been saving up diet soda cans over the winter, etc heh.

I have the materials to build a "more proper" furnace from last fall.  Just need to decide on final dimensions.  This will be a propane fired furnace.



Crucible is still a curious question. 

Graphite crucibles aren't terribly expensive from, say, eBay (even those in the USA etc). 

I've found slightly better prices on steel pipe, but still nothing "great" for casual tinkering.

I have grabbed the cheap $70-$80 flux core wire welder from horror freight - as well as parts needed to turn it into a DCEN welder instead of AC.  Final piece arrived today - so hopefully I can get it converted over the next few days.  Note - I'll have to consider myself a complete noob and starting from scratch when it comes to welding heh.  Been far too long.

Does the crucible really have to be round ?  Sure there's strength to round, but ... ?

Also, when moving to propane, would exhaust pipe actually work out fine ?

blah blah blah blah blah.



I've also been building a cheap CNC machine as a 'toy' ... so ... my time is rather split between work / a bunch of projects heh.
Title: Re: Aluminum melting
Post by: unfy on April 02, 2016, 02:52:26 PM
Made it the April Gretna breakfast yay!

Been working on some of the last bits of the 'first go around' mechanical build of the CNC.  Needed some 4 1/2 - 5 inch 1/4 bolts so ran off to hardware stores.

While checking things out, decided that I would pick up the supplies to attempt to build a simple propane burner.

https://www.youtube.com/watch?v=OuqSe7KqA1s

I would almost call this the "earliest evolution" of simple propane burners, but it's not.  Probably not at least.

Anyway - parts that I'm aware of:

* 1 x 3/4 x 1 black iron T fitting
* 3/4 nipple, 6 to 6-3/4 long (sch40)
* 0.035 mig welder tip
* 1/4 compression to 1/8 MIP fitting (LFA-22)
* 1/4 compression to 1/4 MIP fitting (LFA-23)
* a 6-12 inch section of 1/4" copper pipe
* optional 3/4 to 1" flare (black iron)

Tools that I'm aware of:

* A drill press would be suggested.
* #3 drill bit and 1/4-28 tap (mig tip)
* 11/32 drill bit and 1/8 27TPI NPT tap (coupler that goes in the back of the T)
* File (if the mig tip is too long)

The 1/8 27TPI NPT tap can be hard to find.  The $40 tap/die kit at menards has one.  The $100 kit from home depot has one (I think).  Dunno about lowes / horror freight / etc.

The youtube video suggest the burner doesn't burn right in open air without a flare.  I've seen the 3/4 to 1" used as a flare in other burners even though it's not quite 'perfect'.

YT video also says the burner tube should be 6-3/4" long.  I grabbed an 8" nipple to cut down (if necessary) and a 6" nipple to try using with the make shift 'flare'.



I also grabbed some propane hoses and a 'high pressure' regulator from Menards (seems home depot on 84th in la vista didn't have any).  The regulator only goes up to 20psi - and it's suggested to hit up some welding supply stores to grab one that goes to 30psi... but for my small foundry, 20psi should be more than enough (I assume).

Even if the burner is a failure, I'll need the hoses & regulator for a pro-built burner (there's some really nice looking ones out there for $100-$150).



addenum: 

Corrected and clarified tap sizes. 

Added 1/4" copper pipe to list.

Added second adapter for the 'other side' of the copper pipe to list.

Most burners have some kind of valve near them for a quick safety thing.  I'm not entirely sure if a generic valve would work fine or if it needs to be a special type etc - so I'm just omitting it  :-X



Grabbed a fresh 20lb propane tank in preparation for a burn test :D

Z axis on the CNC is being a pain in the ass. GRRRRRR.  I'll be re-making the carriage nut for a THIRD TIME.  After the CNC goes together today (it better, damnit), I'll get the burner built.  I should have some spare 1/4" copper pipe left over from the copper plating days.
Title: Re: Aluminum melting
Post by: unfy on April 03, 2016, 08:30:40 PM
First run of the burner attached below :D.  Should be able to just barely see a tint of blue on the business end of it.

If anyone sees anything wrong / safety problem let me know!

images are broke, so here's an imgur copy of it:

(http://i.imgur.com/NEdZGLT.jpg)



The assembly I took in short:

Pilot hole the T, follow up with 11/32nd drill the T.

Tap the T with 1/8NPT-27.  I had to use a 3/8 bit to slightly countersink the hole so the tap would bite.  Filing the hole / T flatter would prolly work as well.

#3 drill the 1/4 compression -> 1/8th MIP adapter.

Tap the adapter with 1/4-28.

Install mig tip into newly tapped 1/4-28 hole - run it all the way down so it sits flush.

Install mig tip + adapter into the newly tapped T (mig tip points inside the T, of course).

Attach about 6" of copper pipe to the compression side of the adapter in the T.

Attach 1/4" compression -> 1/4 MIP adapter to other end of copper pipe.

For me it's then copper pipe adapter -> 1/4 MIP/NPT hose -> 20psi regulator -> tank.

No, I do not have a pressure gauge.

Seems to work fine.  Flare changed colors due to heat etc.
Title: Re: Aluminum melting
Post by: unfy on April 08, 2016, 09:15:20 PM
Here's the burner at night.

Also: shortened the copper pipe and got the 'oh ****' ball valve installed.

Hope to get the furnace body and lid built this weekend.

Also hope to get the welder modifications done this weekend as well... we'll see.

CNC might get more done too.  So many projects, so little time ._.
Title: Re: Aluminum melting
Post by: SS_N_NE on April 09, 2016, 12:14:46 PM
Always get a kick outta these posts since I have done a lot of similar tinkering.  Have a paint bucket furnace sitting in the garage somewhere.

For a crucible, I have used steel pipe/tube with 3/16 wall and 1/4 plate welded to bottom and made tongs to fit. Hot things are just soft and need good tong to reduce stress....even on the red hot steel. The steel will contaminate aluminum...but in a lot of cases it is not a real problem and didn't seem to hurt any cast projects I made. There were usually few inclusions since a lot of stuff was cleaned off with the dross or just didn't follow the pour or floated out of the part. Round pipe works since it doesn't have corners for the dross to stick into....your concerns on using square...didn't work on my attempts  :(  It is just easier to use round pipe since cleaning off the dross is easier and pour direction is anywhere instead of a corner.

Didn't catch why you are using pop cans. The resulting aluminum is just scrap.  Aluminum from previously cast items like transmission cases, cylinder heads, etc. will have better casting properties simply because it is a already figured out casting alloy. Aluminum is often referred to as "alloy" simply because it is rarely just "aluminum".  I know this is a kind of elementary statement, but if the intention is to make sand castings at some time, a casting alloy will greatly ensure success.  I worked in an industry where there were a lot of scrap to play with and found salvaging cast items just eliminated a lot of wasted effort.

Great part is that I started my attempts at aluminum casting via a booklet, the internet has since opened way more information than I ever had access to.
Title: Re: Aluminum melting
Post by: unfy on April 11, 2016, 01:07:58 AM
Welder project is on hold while I figure out a few things.  The capacitors won't fit in the existing case, and so I need to decide if I'm gonna build a side car to bolt onto the side of the welder to hold the DC stuff, or just try to resell what I've bought and pick up a $180-$200 welder that's already DC etc heh.

Anyway....



Furnace rammed up.  It's ugly.  Which is fine.  First time doing it it, and not using something all that sturdy for forms etc.

I used the refactory recipe from backyardmetalcasting - which is more or less sand, perlite, portland cement, and fire clay.  So far, seemed easy enough to work with.

I did make a few bone headed mistakes.



I started off by assembling the lid.  Put some 8-32 2"'s in the seams of the ductwork to keep it together and as rebar kinda.  Garage door handles with some 1/4 2" bolts.

(http://i.imgur.com/DBwLTuJ.jpg)



the body assembled.  more 8-32's and garage door handles.  ran around about 1" from the bottom (it's upside down in the pic) to add some extra 8-32's as support. decided to not have any legs on the furnace.

(http://imgur.com/XgFJxHR.jpg)



blurry pic, sorry. sitting in a former.  the former is for 12", so I've got some cardboard wrapped around furnace body as well.  a 1.75" hole was drilled in the side for the burner pipe.

(http://imgur.com/mNfWNdJ.jpg)



showing these out of order.  rammed up the lid last. but need to show some mistakes and those will be in the next post.  used one of the left over 3" pvc pipe cuttings from copper plating days as the vent hole.  I'll assume the 3-3.5" hole will be enough of a vent.

(http://imgur.com/L97kWLd.jpg)



Now for some of the bone headedness.  I decided to use a 6" round piece of duct work as the inner chamber size / form thing...

And I kinda forget about putting a second former up higher so that the entire height of the body is kept roundish.

Here's the body / base rammed up.

(http://imgur.com/ClXXuy7.jpg)



And here's looking inside of the thing.

Yeah, that pipe is gonna make it kind of difficult to remove the ductwork without destroying everything.  Sigh.

(http://imgur.com/mq123Fl.jpg)



Managed to get it removed without too much hassle, actually.  Pulling the seam towards the middle gently managed to get it to break the seam the entire length.  Then continuing to pull the seam towards the opposite wall - it pulled away from the refactory / rolled in on itself a bit.  Some wiggling got it free from the pipe.

The center bit that was near the duct work was a bit higher than the rest, despite my efforts to level everything off before hand.

And look at that round hole (rolling eyes). And how centered it is (more eye rolling).

(http://imgur.com/KEBAU4s.jpg)



And the inside with the duct work removed.  Not bad \o/.  Dunno if the pipe sticking that far into the furnace chamber is going to be a problem or not.

Drainage stuff is visible at the bottom (it'll burn out, although i'll prolly push the PVC out ...)

(http://imgur.com/HCJgVCu.jpg)



Hey look.  Some of the spacers I had planned on using to keep the center duct work .. well... centered.

I also didn't fill the center duct work with sand like I had planned to.  Oops.

(http://imgur.com/5RmpJ8R.jpg)



Now it sits for a week to cure.  Hope to fire it gently next weekend.. maybe even to the point of getting a melt in (we shall see).
Title: Re: Aluminum melting
Post by: unfy on April 11, 2016, 10:43:07 PM
Always get a kick outta these posts since I have done a lot of similar tinkering.  Have a paint bucket furnace sitting in the garage somewhere.

Then pipe up with any obvious 'duh' things I'm missing :D

Quote
For a crucible, I have used steel pipe/tube with 3/16 wall and 1/4 plate welded to bottom and made tongs to fit. Hot things are just soft and need good tong to reduce stress....even on the red hot steel.

shooter's offered to have us dig through his scrap iron pile to see what we can come with.  I can prolly hit a local welding shop.... etc.

I should try to find a scrapper that would let me walk the yard looking for ferrous material to snag.  If such a place exists...

Quote
The steel will contaminate aluminum...but in a lot of cases it is not a real problem and didn't seem to hurt any cast projects I made. There were usually few inclusions since a lot of stuff was cleaned off with the dross or just didn't follow the pour or floated out of the part. Round pipe works since it doesn't have corners for the dross to stick into....your concerns on using square...didn't work on my attempts  :(  It is just easier to use round pipe since cleaning off the dross is easier and pour direction is anywhere instead of a corner.

I've heard about the contamination - haven't actually gotten to the point of casting anything in sand yet, though.  Been just making muffin ingots.

Have seen some crucibles on ebay that aren't terribly expensive - but the tongs for them are like really expensive.  I imagine they're not too difficult to build out of flat stock, though.

Quote
Didn't catch why you are using pop cans. The resulting aluminum is just scrap.  Aluminum from previously cast items like transmission cases, cylinder heads, etc. will have better casting properties simply because it is a already figured out casting alloy. Aluminum is often referred to as "alloy" simply because it is rarely just "aluminum".  I know this is a kind of elementary statement, but if the intention is to make sand castings at some time, a casting alloy will greatly ensure success.  I worked in an industry where there were a lot of scrap to play with and found salvaging cast items just eliminated a lot of wasted effort.

Doing work with cans just to get experience with all of it.  They're more or less a free source of material to work with.  As mentioned - I've not done any real casting with it, so look forward to fighting with it in the future.  I appreciate the heads up that the closer to 'pure' AL that pop cans are will cause possible issues later.

Quote
Great part is that I started my attempts at aluminum casting via a booklet, the internet has since opened way more information than I ever had access to.

Indeed!

And hopefully this thread is helpful to others as well.

So far what I've learned: it's not too difficult to melt metal.  The crucible is of all importance, though.

I'm curious if the burner I'm using needs some choke mechanism added to it.  Won't know until later.



Furnace continues to cure - hit it with another light spray of water when I got home from work.  Flipped the lid and rotated furnace body on it's side so as to expose the sides that have been on garbage bags the entire time.  In the morning I'll stand it back up, maybe even put the lid on it with cardboard separating it.  I will prolly get one more spray in the morning and then leave it alone from there on out.

I have some concerns about the build.  Dunno if I got the refactory wet enough.  It was more or less on the slightly too wet side of casting sand.

Title: Re: Aluminum melting
Post by: SS_N_NE on April 15, 2016, 04:50:43 PM
The steel pipe crucible will work OK for small and less significant parts.

A carbide crucible will not contaminate the aluminum alloy but are fragile. The tongs have to be a very good fit so the red hot crucible full of molten metal doesn't get crushed or otherwise damaged by handling and dump the hot load. Tong are easy enough to make, just have to fit well, and lock in a hold that doesn't squeeze the crucible.  Eventually if you start green sand casting, you may be fluxing, which is a real corrosive process to a steel crucible and is more likely to put ferrous contamination into the aluminum.

Although pop cans are available....it takes a lot to make a small amount of metal....and that metal will not be very usable for casting...just doesn't have the right composition/alloy.

Something like a junk transmission case will yield a lot of casting material. Usually can be found laying around or bought cheap from someone on Craigslist wanting to be rid of the junk. The case can be put on a pile of wood and the wood burned to heat the case. A hammer can be used on the hot aluminum to break off chunks fairly easily (at the right temperature) that can be put in your crucible. Not melting the case, just softening it up a bit. It will be sort of crumbly when hot enough.

The refractory in an oven is a lot like casting sand, you only want it wet enough to hold the materials together while being formed.  After a bit of drying time, you make short runs of heat in the oven to drive out any remaining moisture. Once completely dry, the oven is brought up in a few cycles to operating heat which will ultimately vitrify the refractory sort of melting it together into a porous glass-like state. Each time you heat up the oven, you will need to go slow at first to drive out humidity it collects. If heated without driving out the moisture (from build or air) the heat will steam the water trapped inside the refractory and pressure will blow out chunks of the refractory or turn it crumbly. The effect is usually referred to as spalling.  Sometimes spalling can be fixed somewhat by troweling some refractory back into defects...but spalling is best avoided.

I have plans for an electric furnace...but never went that way. I now generally machine things from billet aluminum.
Title: Re: Aluminum melting
Post by: unfy on April 15, 2016, 11:17:12 PM
Crucibles:

This weekend will be the first couple heatings of the furnace.  I may attempt a melt, I dunno.  I plan on attempting to weld up a crucible but we'll see... time may be against me, etc.

I did order a graphite / salamander crucible off ebay.  It's a #4 A shape, which is big enough to drop cans into.  Will be making my own tongs for it.  Part of the "gonna do it eventually anyway, might as well just get one now" ...



I've gathered up a fair amount of ingotized pop cans.  Just looking at how it poured into muffin tins and how the failed crucible stuff looks - yeah, I can see it not doing so well for casting or serious work.  Granted, I did not flux nor degas it when pouring into muffin tins etc.  Not quite sure if can be alloyed with something 'at home'.  It's been useful as a learning experience, at least.

By your description of how wet the refactory should have been during the ramming process, I think I hit it on the head.  Grab it and squeeze - it holds it shape and breaks cleanly.  And while ramming it up, the 'spray' / 'excess' did act kinda dry, but still would clump if squeezed.  Sooooooo I'm far less nervous about things now.

I am aware of the slow starting heat, and pre-heating any metal molds ya might use (ie: muffin tin) to drive off moisture.  I should find that video of a couple high school or college kids that try to pour some molten aluminum into a metal mold that had a drop of water in the corner (thus, subsequent explosion).  Quite dramatic and a solid reminder of safety heh.

I've seen some folks heat up parts in a barbecue grill before breaking them, too.  Also seen others take a skill saw and just chop it up.  I'm not quite there yet, sooooo dunno what I'd do heh.

Electric furnace: I did buy Dan's electric furnace plans... and I am 50% done building it.  In fact, I was working on it the night of the burglary a couple years ago.  Just haven't been able to drag myself back to it to finish it off.



Keep the advice coming <3
Title: Re: Aluminum melting
Post by: SS_N_NE on April 16, 2016, 12:50:07 PM
I should find that video of a couple high school or college kids that try to pour some molten aluminum into a metal mold that had a drop of water in the corner (thus, subsequent explosion).  Quite dramatic and a solid reminder of safety heh.

I went to an aluminum extrusion plant in SD that had a good part of it's roof missing. They dropped a load of scrap into a furnace and missed a pop bottle that had been tossed in the load (tried to skip pre-heating a load of clean scrap). Don't even want to know what that experience would have been during the event.
Title: Re: Aluminum melting
Post by: unfy on April 16, 2016, 09:38:30 PM
Did the initial cure / test firing of the furnace today.  Was real slow and gentle with it, had it running on as low as I could get it for an hour or two before cranking it up.

I'm happy with the burner.

I'm happy with the furnace.

It was kinda of interesting to watch the furnace 'cry' from a couple of the bolt holes as it drove the water out.

After it stopped forming any condensation on a metal plate semi-covering the top vent hole, started to slowly crank the gas up. 

After turning it off, covering the vent hole with a thin sheet of metal so it can cool as slowly as possible.

I'll get some pictures posted later.

Although no melt was attempted, I will say that so far I am thoroughly impressed with propane / propane furnace.  Is the charcoal furnace worth a go for some early learning ? Yes.  Is moving to propane worth it ? So far a resounding yes.

So far, I'm not entirely convinced that the 3-3.5" hole in the lid was the correct size.  Burner didn't seem to suffer from any back pressure when the hole was 2/3-3/4 covered.  I suppose I could just slap a firebrick on top of the hole in the mean time.  And it's larger size should make adding more metal to the crucible easier... we'll see.
Title: Re: Aluminum melting
Post by: unfy on October 08, 2016, 07:49:13 PM
Was doing a gentle re-heat of the furnace today so can possibly get some melting in tomorrow.  With all the rain and humidity, figure'd it be a good idea.  Seems like it was - saw some steam and then detected presence of invisible steam later.

Since the furnace was gonna be hot even on 'gentle', went ahead and attempted a melt.

Earlier, had built some sand boxes out of some 1x2's, 1x4's, and cheap "plywood".  In case of an accident, molten metal on concrete or black top is a no-no, etc.

Using another cut up MAP gas bottle as a crucible, the melt went fine.  After lifting crucible out and cleaning up the dross - it failed at the 'webbing'.  The melt went pretty quick even on 'low' and the furnace and burner did nicely.  I'm happy.

Tomorrow I'll look into getting some 3/16" rod bent up for "tongs" on a real crucible I snagged off ebay.

Title: Re: Aluminum melting
Post by: unfy on November 20, 2016, 08:49:45 PM
Spent Sat and Sun working on finishing off the can pile.

After a 30-40gal trashcan of crushed cans, and a fair amount of uncrushed cans... I have around 18lb of aluminum ingots.

Some home made crucible tongs worked out nicely.  Two 1/8" x 1" x 36" weldable flat boars from hardware store.  Two bits of 1 or 1-1/8" angle iron about 1" long each.  Some 1/4 or 3/16 (i forget) round stock (also weldable), and an 1" x 18" black iron pipe cut in half to act as handles.



Q & A:

Q) Was working with cans worth it ?

A) Not really. 

It's slow to fill the pot - costing you money in fuel and trying your patience. 

It produces a lot of waste. 

The alloy that makes up cans (ABC or something... american beverage can ?) is not great for casting other things.

Because of trying to gently push cans down into the molten metal / crucible, you're also putting un-needed pressure on the crucible.



Q) Charcoal or propane ?

A) For me, propane.

Charcoal was interesting for seeing what I thought of the process, but propane is just cleaner and less fuss.  It's also cheaper, I think.

Building the burner will take a tiny amount of time, or buying a burner will add a bit of cost - but if you're gonna play with this, might as well just accept these things.

Being able to simply start the furnace and not have to play with charcoal management is a huge benefit.  Also not dealing with charcoal dust is really nice.

I dunno if forced air charcoal can be made to run hotter or not.  Waste oil burners are a valid 'thing' for running hotter, though.



Q) Opinions on the cheap burner made from hardware store stuff ?

A) Works fine for me.  During actual melts I've had no blow outs or any other issues.  I dunno if some flaps for chokes would be of benefit or not.



Q) Bought crucible or home made ?

A) For me, bought.

Food cans really didn't work out well when melting pop cans.  With chunkier source material, it might do okay... I dunno.

Propane bottles really seemed like they wanted to work, but I never had any luck.  Again, using better source metal (not cans) might make them far more viable for a few melts.  The whole 'press the can down into the pool' really seems to hurt things.

Exhaust pipe did somewhat okay... but not terribly great either.  Again - better source material might make all the difference...

Notice a pattern of not liking cans ? :D

Never tried a fire extinguisher.

Never got to try some 1/4" wall pipe or other thick pipe stuff.

I had bought a 'salamander' A shaped crucible.  Fabricated up some lifting tongs.  I'm really happy with it.  3 or 4 melts with no problems what so ever.



Q) Thoughts on the furnace

A) I approve.  It's inexpensive, fun to do/learn-to-do, and works.  And relatively inexpensive. Make your own!

A more round burn chamber would be nice heh.  A slightly larger burn chamber would also be nice to better fit the crucible I have (squeezing the lifting tongs in it is a chore).

I would possibly suggest some kind of more / better re-enforcement inside of it.  I have plenty of screws sticking in from the handles and seems - which the furnace body seems generally okay.  The lid, however, does have a crack or two in it that makes me 'hmmmm' to myself.

Title: Re: Aluminum melting
Post by: Les on November 20, 2016, 08:58:13 PM
Spent Sat and Sun working on finishing off the can pile.

After a 30-40gal trashcan of crushed cans, and a fair amount of uncrushed cans... I have around 18lb of aluminum ingots.

Some home made crucible tongs worked out nicely.  Two 1/8" x 1" x 36" weldable flat boars from hardware store.  Two bits of 1 or 1-1/8" angle iron about 1" long each.  Some 1/4 or 3/16 (i forget) round stock (also weldable), and an 1" x 18" black iron pipe cut in half to act as handles.

Q & A:

Q) Was working with cans worth it ?

A) Not really. 

It's slow to fill the pot - costing you money in fuel and trying your patience. 

It produces a lot of waste. 

The alloy that makes up cans (ABC or something... american beverage can ?) is not great for casting other things.

Because of trying to gently push cans down into the molten metal / crucible, you're also putting un-needed pressure on the crucible.



Q) Charcoal or propane ?

A) For me, propane.

Charcoal was interesting for seeing what I thought of the process, but propane is just cleaner and less fuss.  It's also cheaper, I think.

Building the burner will take a tiny amount of time, or buying a burner will add a bit of cost - but if you're gonna play with this, might as well just accept these things.

Being able to simply start the furnace and not have to play with charcoal management is a huge benefit.  Also not dealing with charcoal dust is really nice.

I dunno if forced air charcoal can be made to run hotter or not.  Waste oil burners are a valid 'thing' for running hotter, though.



Q) Opinions on the cheap burner made from hardware store stuff ?

A) Works fine for me.  During actual melts I've had no blow outs or any other issues.  I dunno if some flaps for chokes would be of benefit or not.



Q) Bought crucible or home made ?

A) For me, bought.

Food cans really didn't work out well when melting pop cans.  With chunkier source material, it might do okay... I dunno.

Propane bottles really seemed like they wanted to work, but I never had any luck.  Again, using better source metal (not cans) might make them far more viable for a few melts.  The whole 'press the can down into the pool' really seems to hurt things.

Exhaust pipe did somewhat okay... but not terribly great either.  Again - better source material might make all the difference...

Notice a pattern of not liking cans ? :D

Never tried a fire extinguisher.

Never got to try some 1/4" wall pipe or other thick pipe stuff.

I had bought a 'salamander' A shaped crucible.  Fabricated up some lifting tongs.  I'm really happy with it.  3 or 4 melts with no problems what so ever.



Q) Thoughts on the furnace

A) I approve.  It's inexpensive, fun to do/learn-to-do, and works.  And relatively inexpensive. Make your own!

A more round burn chamber would be nice heh.  A slightly larger burn chamber would also be nice to better fit the crucible I have (squeezing the lifting tongs in it is a chore).

I would possibly suggest some kind of more / better re-enforcement inside of it.  I have plenty of screws sticking in from the handles and seems - which the furnace body seems generally okay.  The lid, however, does have a crack or two in it that makes me 'hmmmm' to myself.
Title: Re: Aluminum melting
Post by: Les on November 20, 2016, 09:04:37 PM


Can you melt AL alloy?
Title: Re: Aluminum melting
Post by: unfy on November 20, 2016, 10:05:15 PM
Can you melt AL alloy?

That's what this thread has been about :D.

Yes - I've been making some aluminum muffins. It's been a neat learning experience.
Title: Re: Aluminum melting
Post by: Les on November 21, 2016, 07:09:34 AM
Sorry guess I misspoke, meant to say cast Al. 
Title: Re: Aluminum melting
Post by: unfy on November 22, 2016, 02:39:44 AM
I have yet to do any useful casting.  Been mostly just ingot-izing a pile of cans.

I'll be grabbing a thrift store coffee grinder or food processor to grind up some cat litter as a bentonite clay source for green sand.  Will also be making my own flasks real soon now, too.

After that, I'm free to play with trying to cast useful objects.  Whatever those may be - I've got no plans for anything as of yet heh.

Wonder if using some silicone or plaster and other stuff in order to make a pattern or something for duplicating an object... or... I dunno.  *shrug*.  Sadly, a lot of the 'useful' objects ya might wanna make would usually require further machining - which I don't have the capacity to do at the moment :(.  Artsy stuff I can prolly do... but I am not an artist :D



Title: Re: Aluminum melting
Post by: Les on November 22, 2016, 06:56:07 AM
I have yet to do any useful casting.  Been mostly just ingot-izing a pile of cans.

I'll be grabbing a thrift store coffee grinder or food processor to grind up some cat litter as a bentonite clay source for green sand.  Will also be making my own flasks real soon now, too.

After that, I'm free to play with trying to cast useful objects.  Whatever those may be - I've got no plans for anything as of yet heh.

Wonder if using some silicone or plaster and other stuff in order to make a pattern or something for duplicating an object... or... I dunno.  *shrug*.  Sadly, a lot of the 'useful' objects ya might wanna make would usually require further machining - which I don't have the capacity to do at the moment :(.  Artsy stuff I can prolly do... but I am not an artist :D
The reason I'm curious about cast is I have some cast aluminum pole bases and aluminum poles (5" if memory serves) I was planning on scrapping but wondered if they can be melted down for a usefull purpose.
Title: Re: Aluminum melting
Post by: m morton on November 22, 2016, 01:09:07 PM
i did some casting back in school using forms and that sticky oil sand . place an object face up , put the sand on top of it and tamp the sand as you add more and more till the form is full "the forms should not have smooth in side surface" or the sand will not hold to the inside of the form and fall out while flipping them over etc..  ,once full you strike a clean flat top so it can be flipped over, place another form on top fill another form from the back , filling and tamping the sand the form should have a pins or rods to keep them from moving apart or side to side. then after both are filled you separate the 2 forms remove the item being duplicated. and make fill and vent holes plus cut out flow notches to the fill and vent holes . once the aluminum is melted pore it in to the fill and vent holes . allow to cool and remove the cast and dump the sand in a storage ben to be used again.

once the cast is cool to the touch you use a saw to remove the notches and fill hole excess and a file to smooth it to look as it should. i did a few items and i should still have them in a box in storage. was fun projects back in metals class in Jr. high. back in the late 70's

FYI the tacky sand will smoke, so do it in a well vented area ! the sand is reusable till too much of the tacky oil is burned off the sand from the hot aluminum, when that happens the casting will be harder as the sand will not pack as good and crumbles and the vent and fill holes and cast will cave in. not sure if the metals teacher added more tacky oil to the sand or replaced the sand all together ??? sorry never seen him do either . i just know the oil sand started out black & tacky and when it was dark gray it did not work as good and soon after the storage ben sand was black again...

that's what i remember from back then
ever want to try and would like my novice help i live in west Omaha and would need a ride
Title: Re: Aluminum melting
Post by: unfy on November 22, 2016, 03:07:42 PM
i did some casting back in school using forms and that sticky oil sand . place an object face up , put the sand on top of it and tamp the sand as you add more and more till the form is full "the forms should not have smooth in side surface" or the sand will not hold to the inside of the form and fall out while flipping them over etc..  ,once full you strike a clean flat top so it can be flipped over, place another form on top fill another form from the back , filling and tamping the sand the form should have a pins or rods to keep them from moving apart or side to side. then after both are filled you separate the 2 forms remove the item being duplicated. and make fill and vent holes plus cut out flow notches to the fill and vent holes . once the aluminum is melted pore it in to the fill and vent holes . allow to cool and remove the cast and dump the sand in a storage ben to be used again.

once the cast is cool to the touch you use a saw to remove the notches and fill hole excess and a file to smooth it to look as it should. i did a few items and i should still have them in a box in storage. was fun projects back in metals class in Jr. high. back in the late 70's

FYI the tacky sand will smoke, so do it in a well vented area ! the sand is reusable till too much of the tacky oil is burned off the sand from the hot aluminum, when that happens the casting will be harder as the sand will not pack as good and crumbles and the vent and fill holes and cast will cave in. not sure if the metals teacher added more tacky oil to the sand or replaced the sand all together ??? sorry never seen him do either . i just know the oil sand started out black & tacky and when it was dark gray it did not work as good and soon after the storage ben sand was black again...

that's what i remember from back then
ever want to try and would like my novice help i live in west Omaha and would need a ride

This.

That is the process in a nutshell.

I won't be using petrobond (oil bonded sand) - but rather a mix of bentonite clay and sand (aka greensand).  It can't reach the temperatures that petrobond can, and the finish won't be as nice -- but it's far cheaper heh.

There's a semi decent chance I might take ya up on the offer for a bit of help.  If anything - it'd be an excuse to get together over a cup of coffee heh.  Note that I'm doing my melting out of a detached garage at an apt complex - so snow and stuff incoming shall be fun :D.  Don't have a schedule planned yet.  Busy at work, holiday, etc.


Title: Re: Aluminum melting
Post by: unfy on November 22, 2016, 03:23:28 PM
The reason I'm curious about cast is I have some cast aluminum pole bases and aluminum poles (5" if memory serves) I was planning on scrapping but wondered if they can be melted down for a usefull purpose.

I'm currently in the "this has been fun and learning a lot!" (seems a lot of my projects work out that way....)

If you can think of anything you'd want cast, then maybe there'd be a use for it.  There are some rules for casting.  If we go the 'lost foam' route - you construct the object out of styrofoam or insulation foam, we pack it in a bucket of sand and pour the molten metal on it.

2 part casting with flasks (as m morton mentioned) - there are some rules as to what the shape the object is due to the fact that you're taking a pattern / object, cutting it in half, and packing sand around each half... then have to remove the halves.  Think in 3D concerning the sand and you can see how the rules come about.

Any kind of precision object (something you add to reloading press or a firearm) would need machine work afterwards.  shooter has tooling for that, but I do not.  I can grind, polish, drill holes, and tap some common sizes.  That's about it :(

Title: Re: Aluminum melting
Post by: m morton on June 27, 2018, 12:11:46 PM
for you all that melt aluminum this is cool
https://www.youtube.com/watch?v=8Xvsxarw-J0


Title: Re: Aluminum melting
Post by: shooter on June 27, 2018, 03:07:21 PM
 this must drive the animal rights wacos nuts.    but it looks neat. almost like a christmas tree. just put some lights on it !
Title: Re: Aluminum melting
Post by: GreyGeek on June 29, 2018, 07:49:25 PM
this must drive the animal rights wacos nuts.    but it looks neat. almost like a christmas tree. just put some lights on it !
It's a short drive!  Most of them took that trip years ago and never came back.