As our Sinopean friend says, there are really only two standard (read: easy to obtain and cheap) options if you want an integer number of millemetres per revolution. These would be M6 x 1 or M16 x 2.

If you can live with turning partial revolutions and using a graduated dial on the end of the spinny bit, M10 has a lead of 1.5mm, so you need 2/3 of a turn for 1mm and 5 2/3 turns for 8mm.

Dividing the dial into three is easy with just a pair of compasses and straight edge (a method known at the time when Mr Diogenenes was most active).

You could also use M10 and gear it down by a 2:3 ratio (look on youtube for Matthias Wandel and woodgears.ca for how to make wooden gears) so one turn of the "2" gear will give an integer millimetre revolution of the rod attached to the "3" gear.

Engineering problems are engineering problems, no matter what the material is.

If you are thinking about making a jig for finger jointing or box combing, I made one years ago from a drawing I saw in a Woodwork mag. I was quite easy to make, nothing fancy and I,m sure it can still be found in those books.

The whole thing was made from wood, no steel anywhere.

Mel Wilde:

Your jig is likely to have backlash in its movement; not a problem as long as you remember to approach each destination from the same direction ie "take up the backlash".

Apologies from a fellow woodworker if the point is already obvious to you.

Best reason to make something, it also avoids cumulative errors.

M6 is probably more than strong enough for a jig like this if you also use a parallel bar of plain rod to make sure it doesn't bend.

Neil