I just got back from a little store here (I live in a small country town) and they actually have allthread rod! Trust me, this is a big thing, here.

They also have it in english and metric sizes! 8mm fits the shafts of my rollerblade bearings, perfectly.

Needless to say, though, it isn't ACME threaded. I know ACME is the preferred thread design for transmitting loads...but while the loads on a benchtop machine are significant, they're probably not huge.

Two questions.

One: Am I asking for trouble if I use 8mmx1.25 (threads per mm?) rod, instead of the english version? 5/16" is a pretty close fit, but it's not perfect. Will this create problems down the line, with calibration of software written by US programmers, or some such thing?

Two: Should I hold out for ACME threads, or is normal allthread rod sufficient for these purposes?

THANKS!

-- Chuck Knight

8 x 1.25 = .315dia x .0492 pitch

5/16-18 = .3125dia x .0555 pitch

If its being compensated for in the software i would'nt see any
problems.

What he said. Also, think about the nut/tap availability.

Eric

Most all machine tool manufacturers use Metric ballscrews. Software should compensate for the differences.