minimum lead screw size and support bearing sizing

[Swarfing]

I would go for a trap (square) type thread, threaded rod at that size would strip the nut very quickly regardless of the calcs.

[paulus.v]

You can try the 'column strength calculator' from Nook

[dsc]

I thought of using trapezoidal screw at the beginning, but I couldn't find anything with a fine enough pitch. M12 standard thread fine pitch is 1.25, smallest I could find in ACME screws is 1.5.

I'll try Nook, when they fix their website:) (seems to be down at the moment).

Regards,
dsc.