On Tue, 27 Jun 2017 01:36:44 -0000 (UTC), bob prohaska
wrote:

How were crankshafts made before the development of specialized
machine tools? I've looked around on the Web and found no
description that doesn't rely on purpose-built machinery.

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

Thanks for reading,

bob prohaska

General-purpose engine lathes. That's the way engine rebuilders do it
today.

Faceplate fixtures (or special, dedicated fixtures) on the spindle
clamp the ends of the crank in an offset position so that the crank
throws are centered.

Without special fixtures, it's very tedious.

--
Ed Huntress