Re: Model brake component size comparison to prototype

Ralph W. Brown

Hi Tim,
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.  I doubt plastic detail parts made by Cal-Scale or others would or could preform the same function, although I suppose they could be used as “masters” for casting the sacrificial wax patterns, copyright issues notwithstanding.
I suspect there are others here who are more familiar with the process and could provide a more detailed description of the process.
Ralph Brown
Portland, Maine
PRRT&HS No. 3966
NMRA No. L2532


From: Tim O'Connor
Sent: Saturday, April 4, 2020 9:15 AM
Subject: Re: [RealSTMFC] Model brake component size comparison to prototype

As I recall, all Cal-Scale detail components were OVERSIZE because they were used
for lost wax casting! In that process the plastic parts are for the molds and are
destroyed in the casting process, and the shrinkage produces parts that are closer
to scale.

Or am I wrong? :-)

Tim O'Connor


On 4/4/2020 9:00 AM, Lester Breuer wrote:

A comparison of several manufacturers’ model brake component measurements to Westinghouse prototype brake component measurements prepared by George Toman was sent to me for my use.  I asked George to share his measurements comparison on my blog.  If you are interested in the  comparison measurements, they are now available on my blog I have to share photos and writeup of projects on my Minneapolis & Northland Railroad Company. If would like to take a look please do at the following link:


Lester Breuer

Tim O'Connor
Sterling, Massachusetts

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