I have been experimenting with casting pistol frames using lost wax styrofoam. I am reasonably sure I am not the only one.
I do not like getting a solid frame out of the mold as although it may be exact, much interior milling remains. I agree that often on the empty magazine well is partially captured, but using various forms of sand (green, beach, silicone) the internal voids (such as trigger and sear space) are often not captured and come out solid.
Thusfar the best way I have found of preserving hte pin holes as reference points is to place oversize pins in the original, then make my lost wax which copies them. Then when I cast that back into metal at least I have the oversize pins to find my reference points with.
Bur I have yet to find a way of capturing internal voids into the lost wax or the metal. Has anyone done so?
It occurs to me that a semi liguid insulating medium to replace the sand could of course simply flow into the interior recesses where things like sears and magazines sit and then block the metal from going there, but I do not know of an insulator that goes in liquid, then hardens and blocks the metal like sand would. Is there one?
It's sand casting.
Investment casting uses a slurry much like plaster of Paris. It gives a much smoother, more detailed finish. I assume you are casting brass?
Well wiki and I disagree with you. If it uses lost wax, it is an investment cast. ( am not having a detail problem regarding the outside of the frames, only with the interior spaces.
So you are saying there does exist a semi liguid slurry which becomes the mold (presumably with vents and an entry tube to the last was specimen) and into which when molten metal is poured somehow instantly dries and doesn't interfere with the casting process?
Talk to your local jeweler. A wax model with sprue and vent is placed into a crucible and is covered with semi liquid investment. The crucible is then baked at high heat to harden it and burn out the wax model. Molten metal is then injected into the mould either by centrifugal force or air pressure.
Sure, that's a variation on shell molds. For metal you dip in the binder,, then dip into the medium (white sand, etc.) then dip dry it, then dip again and repeat. Usually at least 7 layers are desired to hold the heat of large pours. Then you heat the dip and remove the wax. You then pre-heat to flash off any residue from the wax (or foam). You then add the melted metal.
It is all very nice, but no where in speaking of that do either one of us address the best way of having the hollow spaces inside a pistols frame be reproduced inside the wax mold. What I run into when making the last wax form, even with using liquid silicone mold material, anything that flows inside the metal receiver voids such as a trigger well or a disconnector or sear area cutout either breaks off upon pulling the mold apart, OR the wax model itself breaks during the removal of the mold material inside the voids.
The only approach I see possibly working is the one used by AR15mold. com, to wit, inserting special pieces into a two part mold designed to be removed after the wax portion is formed. I also note that they too use oversize pins to preserve reference points.
There's a kit semi-auto pistol available over here (assuming you like semi-auto's)! Otherwise, you'll have to go here for a SAA "blueprint".
Personally, I want to make a "1858" framed revolver with cylinder chambers similar to those of a Walker (ie., @ 60 gr. capacity), with the mechanicals from a Ruger Old Army (i.e., coil hand, hammer, trigger and bolt springs)!
Regarding the shell casting, here's a webpage which outlines a novel approach of using drywall joint compound! I noticed that (at least for aluminum,) they only recommended a 'double-dip' coating (guess it helps the coating flake off by itself when the object is cast).
What BillDeShivs is talking about is what i believe is called lost wax spin casting. I did this in high school you first have to make it out of wax with funnel leading to the part on a flat piece of plastic or metal than you put crucible. Than you mix up this very fine compound with water and put it on a vibrator to vibrate all the bubbles out of it let it dry than put it in kiln to melt all the wax out and put it on a spin casting machine. That is a big spinning arm that you wind up. It has a crucible that funnels the melted metal into the funnel you made with the wax. When the metal is all melted you trip the wound up arm and it shots the metal in using centrifugal force.
The gent in this video was clued in on a process of ceramic shell casting (I've also read of using drywall joint compound from home depot for ceramic shell casting with aluminum parts): If you thinki you could live with a .38 Spl. or 9mm revolver you could probably do it out of Zamac easily (some types of Zamac approach mild steel strengths, and all are eaily cast at home).
Waffenshmeiden in her Sig series videos came up with a decent method of casting semi auto pistol frames. It took several tries before she came up with a good one.
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