[Public-List] Casting shrinkage

[mpcylinderheads at gmail.com]

I think selling them unfinished is a great idea, like chainplates on our boats I doubt any two boats will have the holes in the same spot. Any local machine shop would be able match your existing one to your new one for not a lot of money and save you countless hours of making the new one fit. Great Idea
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-----Original Message-----
From: Robert Alley <1ralley at comcast.net>
Sender: public-list-bounces at lists.alberg30.orgDate: Tue, 17 Jul 2012 15:21:47 
To: <public-list at lists.alberg30.org>
Reply-To: Alberg 30 Public List -- open to all <public-list at lists.alberg30.org>
Subject: Re: [Public-List] Casting shrinkage

You may be on to something here.  In my misspent teenage youth, I worked 
for a very short period of time at a foundry which did, among other 
things, lost wax castings--i.e., castings in aluminum and brass/bronze 
for which the mold was wax, "lost" up the chimney when the piece was 
poured.  Plaster ( I think-it's been almost 50 years) molds were used to 
replicate the wax castings.  I can (barely)remember building up the 
thickness of cold wax molds when needed using warm wax and a fine 
toothed tool used to give a uniform additional thickness, precisely the 
depth of each tooth. Imperfections were removed in finishing. The 
process was similar to the work of a tiler, using a toothed trowel to 
smooth on a uniform thickness of mud for setting tile.  There is no 
reason the same could not be done to increase the thickness of a pattern 
of any kind--even a bronze shoe.

PS: Costs could be kept down by providing each shoe or other part to 
each purchaser unfinished.  If you have a vice and a flapwheel for your 
power drill or angle grinder and a file or two, you can finish it 
yourself.  People might have to buy (or share) new drills for bolt 
holes-or at least sharpen the ones that have been in your tool box 
forever. A drill press would be best for the holes, but not absolutely 
necessary.

Best to all,

Rob Alley
On 7/17/2012 2:21 PM, Rick Leach wrote:
> Ahoy All!
>
> I don't know enough about the process to know if it would work, but what if the master part were dipped in wax and allowed to cool a few times to increase the overall dimensions enough to offset the shrinkage?
>
> Rick Leach, #121
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