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Post by racket on Jul 10, 2012 2:59:00 GMT -5
Hi Anders
I use to use old car pistons for casting alloy , just find an engine re conditioner and buy his scrap .
Cheers John
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Post by Johansson on Jul 10, 2012 15:46:39 GMT -5
Good idea, might take a trip around the shops in town and ask for donations. =)
I cast the furnace bottom and lid with fire clay half an hour ago, in a couple of days I will find out if it worked as planned and start cutting the bricks to shape.
Cheers! /Anders
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ashpowers
Veteran Member
Joined: February 2011
Posts: 207
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Post by ashpowers on Jul 11, 2012 8:22:22 GMT -5
Some of the best alloy will be found in auto scrap yards - engine mounts, accessory brackets, transmission housings, intake manifolds.... And like john said, Pistonium is also a really good alloy to cast with. =) There is always a nostalgic sense of medieval artistry when casting aluminum - a little more so when melting down old aluminum parts to make new. However, if I could make a recommendation, get your hands on some virgin A356 alloy to cast your parts from. It isn't terribly expensive and the cleaner your metal is, the better the casting will turn out. You'll have less porosity in the part, it will experience less thermal shrinkage through the cool-down, and will have higher strength... I've been casting for 7 years now and have done everything from greensand, petrobond, lost foam, lost wax, permanent mold, - the quality of the metal you melt and pour and the temperature at which you pour it has a lot to do with the quality of the final part. =) Enjoy it! It is a very fun art! Here is a video on youtube of me casting one of our intercooler endtanks. This is the new furnace I built last year with an electric blower burner and permanent molds. www.youtube.com/watch?v=9MYGVBrpGz8I've probably cast 2-3 tons of aluminum over the years now all from metal melted down in the homebuilt furnace.
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Post by turbochris on Jul 11, 2012 10:57:21 GMT -5
I know how to get pistons out of a motor w/o tools. Beer speeds things up. Got some rods and cam pieces out once. One rod landed 20 feet away, is this a record?
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Post by Richard OConnell on Jul 11, 2012 12:10:11 GMT -5
Yeah, I think Scott Knows the same trick Chris. He does so in such a way that it empties the oil from his motor MUCH faster than Jiffy Lube.
I had no idea that manifolds were made of a decent alloy. Always figured they made them out of the cheapest stuff they can get their hands on. I know now, a lot of cars have switched to plastic intakes :/
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Post by Johansson on Jul 11, 2012 15:14:04 GMT -5
Great advice Ash, I´ll follow your and Johns advice and make sure to source some cast alloy parts for the shaft tunnel. The pile load of scrap non-cast aluminum I have can be used for door signs, bookshelf penises and other decorative items. The few casts I have made myself so far really got me hooked, it is incredible fun and with my new furnace I should be able to try different types of casting at home instead of having to do it over at a friends place. So far the lost foam type feels most suited for the parts I am making, but since I have several buckets of casting sand I will try sand casting as well. You´ve been casting aluminum for 7 years in shorts and sneakers and still have skin left on your legs? Now that is quite an achievement!
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ashpowers
Veteran Member
Joined: February 2011
Posts: 207
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Post by ashpowers on Jul 11, 2012 21:29:02 GMT -5
Pistons are mostly made from hyperutectic alloy and contain a good amount of silicon in them - this additional silicon adds a lot of hardness and strength to the metal - they are also usually made from higher quality (purity) alloy and make a really good source metal for re-casting other components. Just so long as you thoroughly degrease any old parts before melting them down, you will avoid hydrogen dissolution into the molten aluminum, which will cause problems. It would also be of benefit to media blast any metal and then hit them with an etching acid before melting them down to remove any surface contaminants. In addition, put a pinch of table salt into the melt and the chloride ions within the salt will bond with the hydrogen gas that has dissolved into the metal and form hydrogen chloride gas, which is insoluble in aluminum. It will "gas out" and remove the hydrogen from the metal, "cleaning" it up prior to the pour....
A lot of the Japanese manufacturers use hyperutectic alloys for a lot of engine part castings, so it isn't just the pistons that make for good re-cast sources. I can't vouch for american-made parts though, I would actually be a bit suspicious of them, but the japs tend to use higher quality metals in their manufacturing...
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Post by Johansson on Jul 12, 2012 0:12:01 GMT -5
At last I find out what the flux added to melts is, I have been wondering about that for some time now and even considered ordering a pound from the US since no-one around here seems to know where to find any in Sweden available "aluminum flux". Thanks a lot for that info! I will ask around at the local car scrapyards for pistons, unfortunately all metal is sold directly to a large metal recycling company that refuses to sell/give/trade away anything to private persons. I have heard about guys with tears in their eyes being denied to buy a pile of stainless tube bends on their way to destruction...
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Post by Johansson on Jul 13, 2012 6:30:02 GMT -5
Some more progress on the furnace, all that is left to do now is to set the bricks with fire proof concrete and make a cheramic coated steel crucible. The propane burner. Everything set up for fixing the bricks, I need to seal the gaps between the bricks first so the concrete will stay in place. I concidered to cut the bricks so they fit seamlessly to each other but I figured it was easier and just as good to fill the gaps with concrete. Cheers! /Anders
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ashpowers
Veteran Member
Joined: February 2011
Posts: 207
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Post by ashpowers on Jul 13, 2012 8:55:32 GMT -5
Hi Anders,
Looks like she is coming along well. What I found when I built my small original furnace like yours was that you really need to have a blower in order to get the temps up. Trying to use a venturi style burner would just take forever to get the heat up. I ended up using a small hair dryer with the heating element removed and it worked like a champ. You will also get much cleaner combustion which also lowers the hydrogen diffusion into the metal.
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Post by Johansson on Jul 13, 2012 13:24:21 GMT -5
Good pointer, I´ll add a small fan to the burner and block off the air holes in case it takes too long to get the heat up.
Would an IR thermometer work on liquid aluminum or is it too shiny for the IR to work accurately?
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metiz
Senior Member
Joined: April 2011
Posts: 297
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Post by metiz on Jul 13, 2012 17:13:58 GMT -5
Would an IR thermometer work on liquid aluminum or is it too shiny for the IR to work accurately? Just use your finger dude
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wolfdragon
Senior Member
Joined: April 2011
Posts: 287
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Post by wolfdragon on Jul 13, 2012 18:35:12 GMT -5
its all "shiny" to IR when it's that hot
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Post by Johansson on Jul 13, 2012 23:25:28 GMT -5
I didn´t mean shiny like in glowing, but mirror-like shiny. I have had trouble getting a good temp reading on polished metal with my handheld IR thermometer, so that was why I asked.
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wolfdragon
Senior Member
Joined: April 2011
Posts: 287
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Post by wolfdragon on Jul 15, 2012 13:34:32 GMT -5
hmmm I've never had that problem before... this warrants a googling...
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