melting aluminum cheaply

I would like to melt a few old (but clean) pistons to pour into the heat crossover passage on a cast iron cylinder head. After doing some research,
it seems melting pistons is quite a popular way to do this. I did a search in this group for "melting aluminum" and many posts were people who were building a furnace and this is getting a little more involved than I was planning. Since this is a one time only thing, would I get the desired results by placing the piston in a cast iron frying pan, and directing the flame from an oxy acetelene cutting torch head (without using the oxygen cutting air obviously) right on the piston? Just not sure if this would keep it in a molten state. Any cheap alternatives to this? CC
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CC wrote:

dont think this will work.. you got to have the molten metal in a furnace to keep the whole thing extra hot... use a piece of terra cotta pipe or even a clay pot and heat the pot with a charcoal fire and let it burn forever in this state and let it melt..........
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I think this would work, maybe even suprisingly well. I know some blacksmiths regularly melt aluminum in iron pans on their forges. I've also heard of people stacking firebrick around a pan set on top of an outdoor cooker burner (clam kettle/turkey frier/etc.). There have even been foundries made from coffee and soup cans and a shop vac, burning briquettes. Do a web search on "coffee can foundry".
With casting any metal, I think the secret is don't stop adding heat at the point where it just melts, keep going just a little hotter to give you time to work once you remove the container from the heat source (or vice versa).
I think the locallized heat from the oxy-acet torch would more than make up for the lack of an oven or big fire to heat it in, as long as we are talking single piston quantities. The worst that can happen by trying this is that you end up with a half-melted piston in the frypan and have to try something else. But I'm willing to wager it'd work.
--Glenn Lyford
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Hi.. I use propane and a design from "Gingery".. Probably the cheapest way is charcoal. You will need some kind of blower. You can stack fire brick into a 'box' and do it that way. An electric cage blower with a pipe going into the furnance. You will have to have a cruciable. I make them from 4" or 6" steel pipe 6-8" in length. Arch weld 1/4" plate to the bottom. You will also need tongs to lift the cruciable from the furnance and pour. Faceplate, apron, heavy work boots and gloves are advised.. If it sounds like alot of 'gear', it is..to do it safe. One mistake in molten metal can ruin your day and alot after that. I'd advise you to at least read alittle about it before proceeding..metal casting is fun, but at 1250 degrees it is'nt anything to play with or not do it right.. Good luck..

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the aluminum will catch fire and burn a hoel in the pan I would not put a bare flame on it to that heat
swarf, steam and wind
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O

Ive never seen aluminium catch fire like that. When I worked at a foundry, I sometimes (like once a day) had to melt out aluminium that had cooled to soon in the mold. Did it with oxy/acetylene. Still wasnt all that quick to melt. It also can create problems with oxides. I would go for the charcoalmelting. As for the fire hazard, al-dust might be a danger. Henning
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henning wrote:

I don't see how this can be, but I think my dad once melted aluminum on a stovetop burner. He was going to make a hardboiled egg, but then went out to the workshop while the water was on to boil and forgot about it. All the water evaporated and the pan started melting. When I saw it (hours later and after it had cooled) there was the pan without any holes and inside was a little round ingot of something silvery.
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You might be downright terrorized at the thought of my direct-melting furnace then ;) http://webpages.charter.net/dawill/tmoranwms/Casting_Rvb3.html Not to mention the tens-of-tons capacity reverb furnaces in industry. <g>
Tim
-- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms
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The key to melting it is blocking any drafts and providing a form of insulation to reflect or radiate the heat back into the crucible or pot your using. You can't get much cheaper than one of those propane weed burners or a propane fish or turkey cooker, and a couple of fire brick to suround the pot. Even dry dirt or sand will do for a refractory for a one time use. Its doable. You can use a heavy can or cast iron melt or cook pot. A deeper container is better than a shallow container. Lots of back yard casters use steel soup cans for a one time use crucible. More than one or so uses and its apt to burn through. I do not recomend a soup can but its been done numerous times. A simple pipe and pipe cap or a piece of steel pipe with a plate welded on the end will serve as a crucible for this purpose.
Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.
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snipped-for-privacy@hotmail.com (Roy) wrote in wrote:

SAFETY...remember.....Molten Aluminum and ANY WATER is an explosive and dangerous combination. (no real 'explosion' but the water turns to steam so fast that the ~1300 degree aluminum is expelled at a high rate of speed). Please pre-heat anything that will come in contact with the molten aluminum to remove moisture.
Some info:
http://www.metalwebnews.com/howto/furnace2/melting.html
--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
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<< You can't get much cheaper than one of those propane

I second the motion, I use a cast iron ladle and a propane fired three legged fish fryer. Make a little cave out of bricks and fire it up. Works great and no castable refractory or other complicated forms to worry about, and basically it cost me nothing since I already had the fish fryer burner and the bricks. But even if you had to buy a fish or turkey fryer, they usually can be found new for under $50 US and sometimes even cheaper used. Plus you can use them for their orriginal purpose, not just melting alluminum.
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Thanks for all the help everyone. I did a look around for the coffee can furnace stuff, pretty neat ideas out there. I did try the oxy-acet torch using the cutting torch head (and no cutting oxy) with the piston sitting in a cast iron frying pan on a stove in the workshop. Yes I had a face shield, welding gloves and long sleeves on. The stove burner was on high and I directed the flame onto the piston. Melted alot of it (no fires) but then I see the piston has metal 'struts' in each side so I quit melting cause I did not want the steel to contaminate or something. Then I looked and my acet tank was getting pretty low so I quit. My neighbor has a weedburner and he says I can use it cause the welding shop is closed so I cant get the tank filled til monday. Then I was searching the net last night I saw the '2 buks' cheapy furnace and a few renditions of it out there from other people. I have a bag of Kingsford BBQ rocks so now I guess I dont no what way to go. Sure wish I had more time to play around with this stuff as a hobby, it is real neat. CC
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For what your doing those integral steel inserts in a piston is not going to hurt a thing. After all your using a cast iron pan and odds are the ladle is steel. Your not making a casting for NASA. There is probably more casting made by hobbyists using a steel pipe and for the little iron content it may contain its minimal at most. No big deal with iron or steel .
Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.
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Charcoal is messy! Here is a link to my turkey fryer/brick pile furnace. I don't use it for melting anymore because it uses too much propane. My new refractory furnace is much more frugal. http://www.plansandprojects.com/My%20Machines / Click on "Homemade Propane Fired Foundry"
Ron Thompson Was On the Beautiful Mississippi Gulf Coast, Now On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
http://www.plansandprojects.com
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<< John213a: sorry for the dum question but I have never seen a turkey or fish cooler to know. Are you directing the flame directly on the cast iron ladle? And where are you putting the bricks? >>
The Turkey or Fish cooker is usually a short three legged stand maybe a foot or so high attached to a steel ring with a propane ring buner suspended under the center of the ring. I place a few bricks on the ring where the cooking pot would go leaving the center are above the burner open (this is where I place the ladle bowl) I then build a three sided structure of on side bricks and roof it over with some other bricks. (for my larger ladle I corble the roof) Turn on the regulator, light the burner and set the ladle on the fire filled with broken up chunks of old aluminium. Lately I have been using the frames of some old copiers that I cut up with a big bolt cutter. I could send you a picture if you want of my setup. Flame bears directly on the ladle and around it, Ladle gets red hot at the bowl but not the handle that extends outside the brickwork. I use heavy firefighter gloves to handle the ladle and pour into baked natural sand bonded molds. Usually I make small plaques and other thin castings. Made custom family name key chains for christmas presents using wood letters from a craft store.
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Well I am close to having everything for the el-cheapo melter, and am going to go with something along the lines of what John213a and Ron Thompson have talked about, except using a vertically mounted weedburner for the heat source. I called around for firebrick and the best price I got was 4 bucks a brick for 2.5 thick x 9 inches long x 4.5 inches wide, good to 2300 degrees. Is that about par for the course? Thank you all, CC
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CC wrote:

There are two kinds of firebrick: the ordinary kind and the special kind. The ordinary kind is pretty much like regular brick, except it's yellow-ish. It's used to make fireplaces, for instance. The special kind is very light, since it's mostly air. This kind has very good insulating value and gets hot very quickly (that's good). It's used to make kilns.
Around here the heavy, ordinary bricks are about $1 apiece and can be gotten as "splits" which are 1/2 as thick (1" +-). The special bricks are much more expensive - your $4 sounds about right.
I use the ordinary firebricks because of the cost (I got them for free.)
Bob
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The "light" bricks (I've heard them called soft fire bricks) insulate much better. I don't know much about melting aluminum, but if you want to reflect heat (I've got a small forge for steel), I think the soft fire bricks are better. I've heard people say that they could not get the hard bricks hot enough to forge steel with the heat they had available. Price-wise, I got my bricks for $2.60 a piece at a ceramics-supply store. -Will
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