Author Topic: Lost Foam Casting: a Crankcase in Zinc Alloy  (Read 21817 times)

Offline Eugene

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #50 on: August 12, 2014, 04:32:28 PM »
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

Offline vtsteam

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #51 on: August 12, 2014, 08:19:50 PM »
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.
I love it when a Plan B comes together!
Steve
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Offline Eugene

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #52 on: August 13, 2014, 04:58:23 AM »
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

Offline vtsteam

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #53 on: August 13, 2014, 07:25:28 AM »
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.
« Last Edit: August 13, 2014, 07:53:07 AM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline awemawson

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #54 on: August 13, 2014, 08:44:42 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

Heavy trousers with the legs outside your boots, or alternatively wear a pair of leather spats as sold by most of the foundry suppliers
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #55 on: August 13, 2014, 09:45:18 AM »
Leather boots these days tend to have synthetic fabric tongues, which hot metal will go through like foam. Never had it happen while pouring, but did when a spatter from welding hit the right spot. The tongue and lace area are a perfect shape for trapping hot metal.

I have a pair of welder's leather boot protectors now -- purchased cheaply on the Internet -- basically just a flap of cheap cowhide with leather straps the wrap around the bottom of you boot to hold it in place over the top. Metal will bounce and roll off leather as long as there is no recess to trap it. You could probably even make some kind of guard out of old welding or work gloves. Just something to cover the tongue area of a boot.

I get more serious with leather protection for iron than I do for aluminum -- but my aluminum pours are small. Jeans for aluminum in hot weather. For iron, I have a leather shop apron that goes below the knees, and a leather welder's cape for topside protection. I wear a welder's helmet with a clear glass when pouring any metal, and of course welder's gloves
I love it when a Plan B comes together!
Steve
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Offline Eugene

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #56 on: August 13, 2014, 10:06:01 AM »
Thank you both.

Steve, the trolly is at least in part a matter of storage; I'm so hard pressed for space it's impossible to keep the smelter and the bits and bobs indoors. If it, the pouring table, and tool rack are all of a piece I can make a waterproof cover for the assembly and stash it behind the kennels along with sundry other crap err vital equipment.

As a kid I worked in drop forges and die casting shops. In those days foundry boots were wooden soled with steel rims and heel segs nailed on; the heavy leather uppers were a bit like a wrap round jodhpur boot and fastened with a buckle at the back of the ankle. They were surprisingly comfortable and easy to wear. Looking back I probably spent the first 15 years of my working life in boots of some sort and even at my great age my tootsies are in fine fettle; the rest is falling to bits but the old plates are A1.

Eug

Offline Dawai

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #57 on: August 16, 2014, 11:21:42 PM »
Neat steam engine crankcase.. I tinkered a bit with a triple expansion one years ago. (H2O2 steam generation by silver catalyst)

Casting:
You must really pay attention to the clothing, I was using a cutting torch and my "polypropylene" tennis shoes caught fire.
My old instructor would have been happy with the way I was flip kicking that foot trying to put the fire out. Finally the shoe came off and blazed in the corner while I hopped about. (plasma cutting in flip flops is worse)

Cold weather Snow-mobile suits, zip up style, are also highly flammable.

My green welders jacket that came from a Nuclear job, the fire retardant was "washed" out long ago by improper laundering. I think it is cotton, which smolders and burns, but does not burst into flame.

I seem to burn my beard back to the welding helmet monthly.. It is half the length of my profile pic, never burns back evenly, always one side or the other.
I Hung a 24 foot Ibeam this morning in the ceiling by myself, programmed a Arduino this afternoon for a solar project, Helped a buddy out with a electrical motor connection issue on the phone, then cut up a chicken for Hotwings. I'd say it has been a "blessed day" for myself and all those around me.

Offline vtsteam

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Re: Lost Foam Casting: a Crankcase in Zinc Alloy
« Reply #58 on: January 13, 2018, 06:08:19 PM »
Photos restored after Photobucket broke the links.
I love it when a Plan B comes together!
Steve
www.sredmond.com