The Shop > Metal Stuff
Lost Foam Casting: a Crankcase in Zinc Alloy
Eugene:
Steve, dozy beginners question ..... what gauge ally do you use? I don't have any to hand so I can buy whats best for the job, anything from .5 mm upwards.
Eug
vtsteam:
Eugene the best aluminum for casting, in my opinion is scrap that was a casting itself. Try going to an engine re-build shop and asking if you can buy some pistons pulled out of old engines. They will likely sell them to you for a very small price. They make very good material for casting.
Eugene:
Steve, my bad, I meant the gauge of the stock you use for the templates.
I'd already decided on old castings only as raw feed material; I think a couple of car wheels from the local scrappers is the right way to go, and / or plus pistons as you say.
It will be a while before I'm fully kitted out for casting; my first issue as always is safety, so I'm making sure everything is strong and stable and that I'm in the right PPE. I qualified as a Safety Manager some years back, so it would be a bit infra dig (as well as painful) to become the owner of a bootful of molten ally. :) I plan on making a wheeled trolly that won't be in danger of tipping when the smelter lid is opened, plus having the casting box on a dry sand bed.
Eug
vtsteam:
Eugene, sorry, I misunderstood re aluminum for templates. I just use hardware store aluminum utility sheets used for patching etc. I don't have my calipers here in the house right now to measure the gauge. I have also used aluminum roof flashing, though that seems somewhat thinner, and I like the utility sheet better.
Aircraft pattern tinsnips will make short work of either. Just like using a pair of scissors.
I print out patterns from my computer, cut the paper out slightly large then spray lightly with contact adhesive, and the aluminum template stock as well, I do this outdoors on the porch. Let dry briefly, then stick the paper down.
Cut out the templates just outside the line.Then clean up to the line with a fine file.
I punch or drill holes in templates to accept straight pins or finishing nails for temporary attachment to the foam while hot wiring. Sometimes I use a bit of scotch (celo) tape to hold the pattern on, too, if needed. The hot wire will cut through it.
ps, always clean your hot wire before cutting (or after, if you're an organized person!) with a quick wipe with a rag or paper towel wadded up and the wire hot. Your cuts will be much better.
Working outdoors, or proper ventilation is essential when wire cutting.
I don't think a trolley is necessary for pours of 5 pounds or under, and don't own one. Proper holding shanks and lift out tongs are essential. I like my new springing ring shank for iron or heavy pours a lot (see my oil furnace thread, I believe for a picture). It grips the crucible with, well, an iron grip.....
For aluminum pours I like a cast iron plumbers pot as a crucible. If you're finicky about iron in the melt, just coat the inside of the pot with sand and fireclay mix as a wash. I did so with my zinc alloy pours.
If used bare, it has the advantage of heating up faster and being able to be gripped with a long handled pliers arrangement by the lip, which would shatter ceramic crucibles. I added tube handles about 18" long to a pair of large long nosed offset pliers when I first started pouring twelve years ago, and got in the habit of using it. The advantage is you don't have to transfer the pot to a shank, but just pour direct. This is for small pours, under 5 lbs, again.
awemawson:
--- Quote from: Eugene on August 13, 2014, 04:58:23 AM --- I qualified as a Safety Manager some years back, so it would be a bit infra dig (as well as painful) to become the owner of a bootful of molten ally. :)
Eug
--- End quote ---
Heavy trousers with the legs outside your boots, or alternatively wear a pair of leather spats as sold by most of the foundry suppliers
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