In article , Harold & Susan Vordos says...

The use of shims for machine tools is sort of bush league. One of the
problems of shims is if you dismantle the object, there's no guarantee the
shim will be replaced, nor that it will be replaced where needed. In
machine tools, you pay for precision, which can include scraping or
precision grinding. Shims are a dodge to avoid doing so. That's not to
say that a shim doesn't work. Of course it does. You just don't have as
much control over the end result that you might have by doing it "right".

It's more than just 'not right.'

In this case the issue is an angular mis-alignment of the
column with respect to the table. Placing a shim under *one*
side of the column base means that the contact area between
the two parts has been drastically reduced.

That's the whole idea with fitting parts by hand-scraping,
to obtain large, uniform contact areas to enhance stability
and rigidity.

And yes, I've personally seen asian mill-drills with just
such shims installed - right from the factory! The
interesting thing was, they were made of copper, and taped
in place under the column!! How's that for stability?

Jim

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