Any tips? trying to replace a plastic part that broke from the solar roof of my car.
So far, I've seen that fine sand (90%) + bentonite(8%) + water(2%) will do the trick for molding. Is this OK? Are there better alternatives?
Also, will be using wood coal for the kiln. Is propane necessary?
Too brittle.
Too much oxygen.
You would have to drink a lot of beer to get enough aluminum to cast things.
>>961460
THat seems pretty non sequitur. Did you read a different thread?
>>961455
Propane isn't necessary. Built a coffee can furnace and melted some shit on my terrace cause I live in the city. Worked like a charm
>>961467
make it 60
cans make a shitload of dross
I was the pressure tank submarine guy from a while ago.
This seems like the most viable way to create an internal support structure.
lost foam casting
https://www.youtube.com/watch?v=MqTKdCu6uBw
>>961579
Although easier, this method can't make a detailed piece.
>>961467
I've read before that the aluminum recovered from cans is pretty shit, mostly because there's so much slag involved.
Wouldn't you be better off with old heatsinks or larger chunks of aluminum that haven't been anodized or covered in some way?
>>961957
I dunno, maybe that's right. Will try first only with cans, and will do another batch with heatsinks this weekend. Will post pics for comparison.
>>961820
it's pretty hard to make a detailed piece with sandcasting in general, especially if you're using diy cheap stuff instead of nicer stuff.
a neat tip i've heard about lost foam is dipping your foam blank in a bucket of drywall plaster to build up a shell will provide a much smoother surface (because you get an imprint of the foam surface and not sand textured version of that) and reduces inclusions. and then just chip off the drywall from the mold when done, the shrinking of the piece as it cools will help a lot. you do have to worry about vent holes for larger pieces though.
>>961455
if you're planning on using cans expect 50-60% of it to end up as dross cans are garbage for casting me and friends had to learn that lesson the hard way.
>>961467
oh shit don't use that guys vid his measurements are off and the lid is prone to cracking from thermal shock trust the voice of experiance
>>962085
Good to know, do you have a better recipe using sand and plaster of paris?
>>962117
the half and half sand/plaster is good, but his vid has a lot of bad info. IE the $20 is just for the plaster and sand if you have to buy tools it ends up much more expensive. Also charcoal briquettes are a terrible heat source they make a ton of ash and don't produce near as much heat as say lump charcoal that you can get at home depot for about the same price as the briquettes. also drilling the hole for the air vent is a bitch to get just right. The fire extinguisher crucible is fine but at high temps i've had them fail and piss aluminum into the bottom of the foundry.also the foundry itself is a bit small just my two cents on that one. The basic idea is okay but he fails to mentions a lot of the potential problems and my friends and I where rather disappointed it didn't live up to expectations.
>>961957
>>962084
You can make cans work pretty good if you pre-incinerate them. Takes all the paint, removes any liner material and reduces the amount of dross you get.
Pic related, my last melt batch. About 140 cans, just shy of 2kg in aluminum. Dross was about 200 grams.
>>962558
>pre-incinerate
Have you tried *not* doing that and comparing results to cans directly semt to the melt? I can't help but imagine your method might be oxidizing the aluminum amd netting you lower ingot yeilds.
I have read when melting cans, it's best to melt down a chunk of pure aluminum for the cans to drop into so they'll melt quicker and result in less oxidation.
>>962580
I have, and the quality of my pigs went way up after I began incinerating. The key is using a reducing flame to prevent oxidation. I'm not talking an open burn in a barrel or anything like that.
>>962707
Which flame? Are you suggesting industrial methods to melt simple cans? Remember that this is /diy/.
>>962842
A reducing flame. It's easy to do /diy/, really. I have a homemade propane fueled incinerator. Only thing I have to do is throw them in a burn vessel (I use an old steel bucket) and reduce the vent flows to kind of choke out the flame.
What's the best flux for melting aluminum?
>>963634
borax. its cheap, and it generally works well as long as you dont overheat the aluminum to boiling. I'd only use a flux if you were using an impure mix of aluminum and other metals.
i've been okay just melting aluminum without it since i dont wait very long after a full melt to pour.
Dont use aluminium that has been "extruded".ie heat dinks or cans or other similar items.
only use items that are "cast" ie gearbox or similar..
>>961455
>Any tips? trying to replace a plastic part that broke from the solar roof of my car.
If you are in Middle Tennessee or Atlanta Georgia, I can help you cast it. [email protected]
If you aren't, the easiest way with the crappiest surface finish is lost foam casting. Cut foam to the desired shape, glue on a foam sprue, bury in dry play sand, pour molten metal on top. Very easy. Grind the cast part to smooth out the bumps and divets.
Broken lawnmower engines are good casting alloys. My favorite casting alloy is busted lampposts. My mom keeps running hers over, and I keep turning it into lamp-postium ingots. ;D
>>964984
>Elizabeth.a.greene
What about west NC?
>>964660
why?
heatsink al seems pretty pure
>>965244
He's a moron. There's no difference between extruded aluminum and cast aluminum, because extruded aluminum must be cast into ingots first.
>>965601
Apparently the aluminium used for gearboxes is the same as aluminium used for window frames now..........same strength ..i think not.
Also not an idiot..but have a nice day
aluminum doesn't oxidize outside of a lab environment. it has a 99.999 retenchen rate for reclining. so no slag unless there are impurities in the metal in which case you didn't need it in the first place. dont know what the aluminom % is of what your useing though
>>965657
Still an idiot. Extrusion is merely a way to shape metals. It does not weaken the metal.
>>965914
Check types of aluminium on net and strengths m8
>>965914
So your saying cast aluminium pistons are the same as extruded window fram alloy..........and whos the idiot..
As far as strength goes there is different alloys for diff purposes.
This is my piont here..plz dont split hairs with me m8
>>965939
Aluminum alloys, ALLOYS. Aluminum, pure AL by itself doesn't change because it's extruded or cast.
>>965942
No, you're the moron who assumed that we're talking aluminum for home furnace sand casting. You know, where scrap is scrap and nobody really gives a damn about purities? Aluminum, pure aluminum, is the same strength. For someone doing backyard casting, there's no difference.
On to alloys. Most gearbox castings are made with A356 alloy, which allows aluminum content as *low* as 91.05%. Piston heads? 11-13% silica (4032 alloy.) Soda cans are usually made out of 3004 alloy, which has a minimum aluminum content of 95.6%. So, your "gearbox" and "piston" recommendation for being better for backyard foundry casting deliberately introduces extra impurities which separate out as dross when you're melting.
Again, you're a fucking moron.
>>966039
REKT
Would I be retarded if I tried to make a revolver out of aluminum castings?
>>966110
Can heat treatment do anything for this?
>>966112
Do anything for what? Please clarify.
>>966039
put_down
>>966116
Grain structure and strength.
>>961467
To avoid oxydation, use Sodium Borate or Boric Acid (sold as cockroach posion)
Put a nice amount in thecrucible (tin can may work) and it will melt and acts as a barrier for the oxigen. Then, start adding aluminum till you have nice enought for the piece.
You can melt aluminum with a blowtorch and a flowerpot furnace (once i use a Bunsen burner instead of a blowtorch)
https://www.youtube.com/watch?v=hHD10DjxM1g
https://www.youtube.com/watch?v=lSoWxG30rb0
>>966039
Cant we just be fwends
>>965601
Is not exactly the same, cast alloy usually have silicon to reduce the surface tension and make the aluminum copy perfectly the mold.
Extruded alloy may not copy well the mold if it has too many details.
It's just that.
>>966123
If you heat and water quench aluminum alloy will end with no grain at all
Exept alloys between 3 and 5% of copper and or 1 to 7%zinc.
Ypu can heat and quench to solften the aluminum and then heat it to 120ºC to aging (hardening) the metal
>>966123
Gotcha, and yes, it does. Realigns the crystalline structure of the metal and toughens it, just like with iron or steel. Your graphic has the key though, when the shit is hot you must work with it then. Heating and cooling will lead to "aging" the metal. It'll get harder, yes, but it will become brittle requiring you to anneal it to get it back to a workable state.
>>966134
That's for steels
Heating and rapid cooling of (heat treatable) aluminum alloys cause annealing.
Constant heating under eutectic temperature will cause aging (hardening)
>>966126
Borax is ok as flux, but not great. Regular table salt is better.
As for a crucible, be careful with steel food cans. Thin walls and aluminum ingests steel at temp, so you may have a vessel failure.
>>966139
yeah, i forgot that one, i use to use rock salt
>>966129
M8
