Re: Model brake component size comparison to prototype

Ralph W. Brown

Hi Dennis,
Live and learn, I guess.  Admittedly, what know of the process was learned a few decades ago, so I stand corrected.  It would be interesting, to me anyway, to know what types of plastic are used and how the shrinkage of the various materials compare.
Ralph Brown
Portland, Maine
PRRT&HS No. 3966
NMRA No. L2532


From: Dennis Storzek
Sent: Saturday, April 4, 2020 2:06 PM
Subject: Re: [RealSTMFC] Model brake component size comparison to prototype
On Sat, Apr 4, 2020 at 10:36 AM, Ralph W. Brown wrote:
My understanding is that the sacrificial material used to make the molds for casting is, as the name of the process implies, wax, which melts and is absorbed by the mold when it is first heated leaving the void later filled with molten brass or other casting metal.
Wax was used when the masters were being "spin" cast in rubber molds. For higher production numbers the masters are injection molded from styrene. Precision scale Co. plastic parts are the same; investment casting masters sold as parts. Come to think of it, Grandt Line once sold their parts in brass, also.

Dennis Storzek

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