Re: Scale Digital Caliper

soolinehistory <destorzek@...>

--- In STMFC@..., "Schuyler Larrabee" <schuyler.larrabee@...> wrote:

But I do find that having the five digits to the right of the decimal allows
me to use my dial caliper more accurately, as I can nudge the needle to
approximate at least the fourth digit. A half inch is slightly less than
.006. Can anybody tell? No, but I feel good about it.

The problem arises when people internalize the incorrect scale factor, then apply it to large dimensions. Example:

A nominal 40'-6" freightcar is 486" long. Properly scaled, that's 486/87.1 = 5.580 actual inches.

Do the same calculation using 1" = .012", and you get 486 x .012 = 5.832 actual inches.

5.832 - 5.580 = .252
.252 x 87.1 = 21.95"

You've just built a model that's almost two HO scale feet too long. And people had a fit about the Branchline 41'-6" boxcar.

All these estimations have a use, and a place where they are appropriate, but we need to realize what we are doing. Some of the recent messages here are telling me that some people might not.


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