m16 studding work instead of ballscrews ?

[Robin Hewitt]

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

[BillTodd]

One point to watch out for is that the pitch tends to be slightly greater than standard on rolled threads (rather than averaging out), so a 100 turns on a 1.5mm pitch may well be greater than 150mm.

You'll need to calibrate the exact pitch when you set-up the axis params in mach or emc.

[edit] tip: if you are buying mail order, buy three or more lengths - they'll almost certainly be taped together when packaged so will be less prone to being bent in the post

[edit2] I don't see the point of using M10x1.5 over M8x1.25 - it'll have larger drag (because of radius & circumference) than M8 for little gain in pitch. Irving's suggestion of 12mm x 3 acme/trapezoidal from Marchant dice sounds a better option.

[edit3] As soon as I get my travelling steady finished, I intend making a 5/16" 11TPI with new roller nut idea, for my engraver .