General Categories > Non Gun Stuff
Aluminum melting
unfy:
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.
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.
unfy:
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:
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.
unfy:
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 ._.
SS_N_NE:
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.
unfy:
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.
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.
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.
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.
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.
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.
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).
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 ...)
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.
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).
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