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AndrewB

Smelting Furnace Advice requested

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Hey guys sorry haven't posted much here lately in the last couple months or so but I've been pretty busy with IRL stuff.  I haven't had much time to do any forcing.  How ever I do have all of my fire bricks still I'm in the consideration of starting to do a little bit of aluminum smelting with left over soda cans and what not.  So I'm also planning on sticking to a coal foundry I did order a crucible for coal forge I did pick that up as well as an ingot mold.  So those will be here on Monday.  Not a bad price either.  I know I could use my coal forge fire pot to do the main smelting.  But I wanted to put together a smaller foundry so I didn't have to lug the big forge out every time I just wanted to smelt down aluminum.  What would you guys recommend on this build?  I have the soft fire bricks and still have half a bag of the 3000 degree satinite powder.  Thanks in advance guys.  I am looking to stick to coal on this build since I've got plenty of it.

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First, smelting is converting ore to metal.  You're just looking at remelting.  Second, I would recommend you try it with your forge fist, since you have it already.  From there you can see what you like and don't like about it.  Third, make sure you follow the instructions for your crucible pre-heating so you don't crack it.  

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Fourth, aluminum cans are not good scrap for casting.  Start with something that was cast to begin with.  With cans you just get a foamy mess.  Pistons, bellhousings, stuff like that is the preferred stock.  Fifth, look at backyard foundry setups.  They are almost always enclosed, very important with aluminum since it conducts heat so well.  You can easily get a molten crucible with a solid top, not a good situation.

There are a couple of forums just for this sort of thing.  You will note none of them use coal, the sulfur is just as bad for aluminum as it is for iron.

First, buy this book, it's as simple as it gets: https://gingerybookstore.com/charcoalfoundry.html

Then look at this site:

http://www.backyardmetalcasting.com/

 

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Can we renumber these so Alan's points come before mine?  B)

Also, foundry101.com is a good source of info, if a bad (awkward) website.  

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Posted (edited)

okay so like a bunch of old lead tire weights or fishing weights would work great? Thanks guys.

Edited by AndrewB

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Those actually are lead, so there's that.  <insert general lead warnings here>

That said, I use that to cast bullets.  That is mainly because it is fun, not because it is cost effective.  

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Ahh damn I fazed that one LUL I will hunt around on amazon for some aluminum rods and stuff I wont do the soda can stuff. unless I really know what I'm doing.  but with running the crucible in the forge would that work as good as any foundry or would i just have to pile on the coals?  I picked up this crucible https://www.amazon.com/gp/product/B07H1DSTKN/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

and this ingot mold https://www.amazon.com/gp/product/B01DHVLBOM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

not sure how well those will work actually but I just typed in coal forge crucible and that's what came up.  Just not sure because of the depth of the forge on how much coal I would actually have to use LOL.

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The crucible is fine, if you use it in a furnace rather than a forge.  The ingot mold is nice, but tiny.  Most pople running aluminum use an old muffin pan.

Uneven heat will crack the crucible in short order, which is why I gave you those links.  It is silicon carbide, and they are tougher than clay graphite, but they are still fragile.

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That's what I was primarily concerned with @Alan Longmire was the crucible cracking due to un even heating.  That's kind of why I was opting to build a small coal foundry as well before the summer is over.  Just for that crucible to sit in so I could get an even heat around the hole thing.

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You could do that with the forge you have, just build up the walls with brick on that.  

Also, if you think propane is scary, liquid aluminum probably isn't for you.  That stuff sticks to you.  

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Posted (edited)

Okay yea I can do that I've got plenty of soft fire brick and then that would be easier than just buying material to build a foundry.  But with the coal forge being a bottom blast how would that effect the crucible?  wouldn't it get hotter at the bottom of it? because of the air blast?

 

Edited by AndrewB

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With coal, yes.  If you forced me to try it with your forge and a pile of bricks, I'd use charcoal and bring up the heat slowly until the charcoal is burning all the way to the top of the crucible.

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Posted (edited)

The problem with using charcoal is the sparks lol I don’t think I could get away with it I’d probably have to build a foundry that sits on the ground if I go the regular charcoal way.  Just because I want to be careful and not catch anything on fire and because of the open flame policy here.  So I wouldn’t be able to do the charcoal in my main forge. Unless it was almost sitting on the ground

Edited by AndrewB

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Welp LOL the Crucible is a good decent size for me.  You guys weren't kidding this mold is TINY LOL.  but it would probably be perfect for smelting gold into bars if I ever get there. LOL but yea I'm very happy with the crucible not bad for 30 bucks. The ingot mold is about the size of a small candy bar.

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Well the good news is folks I've made some progress on everything, its just been slow because of the heat we've had here over the summer too hot to run the forge.  But what I've basically done was I re purposed my old break drum forge for the smelting and casting forge.  It should still hold up great for that purpose.  I doubt I have what it takes to be able to cast steel but that would be a fun attempt LOL.  Anyhow I've been working on modifying my break drum forge just a bit so I can place fire bricks around the edges of the drum fortunately the height wasn't an issue and I only needed one brick to barely go just above the top of the crucible I may have to add more once the coal is in the forge but that's alright.  At least I'll have a furnace up and going pretty soon, I also ordered myself some muffin tins got 2 for the price of 1 thank you amazon for that LUL.  I wouldn't mind attempting on casting a few brass knives at some point that would be an interesting experiment to do or attempt.   I'm not I've kind of taken a break from making knives at the moment since I've gotten a bit on the frustrated side with it LOL.  But I'll go back to it sooner or later.  I figured Id give casting the try out for the time being.

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If you do brass, stay upwind.  The zinc boils off in a lovely yellow cloud of nastiness that can kill you if you have any respiratory issues.  If not, it'll just make you wish you were dead for a few days.  And you have to replace the zinc as you go to keep the brass, well, brass.  

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20 hours ago, Alan Longmire said:

If you do brass, stay upwind.  The zinc boils off in a lovely yellow cloud of nastiness that can kill you if you have any respiratory issues.  If not, it'll just make you wish you were dead for a few days.  And you have to replace the zinc as you go to keep the brass, well, brass.  

I'm not sure if I plan on doing brass right away, I'm going to stick to aluminum since I'm finding that it's the noob thing so for now it will be strictly aluminum.  I've just been having issues on where I can locate the proper sands for making the molds just a pain.  I've been doing a lot of research and looking for where I can get.  I still am not happy with the bottom blast with a foundry I'm also not sure how well that will effect everything even with the coal.  I just dont want the crucible to over heat and get ruined.  I mean yea it was only 30 bucks so its not bad to just go buy a new one but still LUL Id like to keep the crucible intact.  How ever on the sand I'm just having a hard time finding it for cheap.

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Sand for sand casting or for investment?  I think you should be able to get fine enough sand at Home Depot or Lowes.  This one says it is a 30-70 sieve, which is still pretty coarse.  If you found something finer, you could blend them together to get a pretty good mix.  It all depends on how nice of a surface finish you want.  If you find that you want a nicer surface finish you can also add a mold wash.   

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52 minutes ago, Jeremy Blohm said:

Try THIS google search. 

I looked at everything in the first page of results from that search.  That is not a path I would recommend.  Green sand casting is very simple for a hobby level.  I'd even recommend looking at oil sand casting for low temp things like aluminum.  Paying someone else to mix your sand is a bit of a waste of money.  

Check out this thread.  

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Yea @Jeremy Blohm I've looked into those links, @Jerrod Miller I haven't fully dived into that thread as of yet. I will be fully diving into it at some point soon.  How ever I did happen to make a phone call to the Clay Arts Center here out of Tacoma and they happen to just have the type of sand and clay that I need.  So I'll be ordering a 50 pound bag of each to start out with.  I'm still going to have to forge out my crucible tongs and what not and things I need for that.  Fortunately I have a smlaler crucible.  Muffin tins for first poors are already in hand as well as stainless steel skimming spoon.  I'll probably need to make a smaller one to fit the crucible LUL.  Amazons kind of a cluster for not having a good size estimate.  Either way I'm so far on a role with everything.  I've still got to acquire a couple more things to fully get started still a bit concerned about using a bottom blase air source I'm considering re designing it a bit so it doesn't have a bottom blast and go for the side blast which would make a bit more sense to me.  Also @Jeremy Blohm  I've looked at all of those links when I was hunting around for information about casting sand LOL. So I saw those the other day.

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Out of curiosity, what sand and clay will you be getting?  It should be something along the lines of AFS 70 GFN (that is the American Foundry Society 70 Grain Fineness Number) silica, and a southern bentonite (possibly a blend).  

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