Re: Scale Digital Caliper

Tim O'Connor

Right. It's easier to remember that with 87.1 scale, and a digital
caliper that breaks an inch into 1000 parts, that each part is a scale
.0871 inches (and .048 in P:48 and .064 in S scale)

So to convert the digital readout of 5.580 into HO scale, just multiply
5580 x .0871 = 486.02" . In other words, ignore the decimal point, and do
the multiplication. This is why it would be so easy to change the readout
to HO scale - Assuming you can handle HO dimensions in decimal. :-)

Tim O'Connor

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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