Aluminum melting

[unfy]

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.

[unfy]

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 .

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 ._.

[DenmanShooter]

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.

[Mali]

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.

[unfy]

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

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

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

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

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

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

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

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

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

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

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.

[unfy]

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.

[shooter]

 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.

[unfy]

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

The above discusses using portland cement with other things.

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/

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/

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.

[Mali]

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?

[unfy]

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.

[unfy]

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.

[Mali]

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?

So much time to just prove that you should burn out the moisture first.

[unfy]

This video?

So much time to just prove that you should burn out the moisture first.

That's the video

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 .

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.

[unfy]

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.

[unfy]

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.

[shooter]

 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?

[unfy]

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).

[unfy]

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.

[unfy]

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.

[unfy]

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).