Quote Originally Posted by irving2008 View Post
M10 is 1.5mm, which makes for slow traverses unless you gear up but then that adds cost/complexity.

M10? I'd go for around M4 :whistling:

Okay you need to gear it up a tadge and hold it in tension but the frictional losses will be so much lower and no way could you pull M10 straight.

Real engineers from days gone by had no fear of disadvantaged gear systems.

You can't get 100% straight with anything but the thinner you go the better the approximation. There's a wonderful piece of accidental verse in the Oxford Dictionary or Quotations...

...and so no force however great
can stretch a cord, however fine
in to a horizontal line
that shall be absolutely straight