60 degreee thread ( hijacked thread

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Miroslav Pejic <peja@n...>
wrote:

> Hi group members
> What's 60 degree thread? Isn't this standard screw?
> Short time ago I asked about using this type instead of ball screw

and get

> negative opinions.
> What's now?
> Peja

Yes, 60 degreee thread is standard thread.
yes is is bad
yes it can be used
yes many do use it.

When you push on something with a thread, the angle allows the nut to
climb or expand as not all force is being pushed in the axial plain.

ACME is better as it pushes more force in the Axial
and ballscrews are the best.

we rate these with an efficency. ball screws are better than 80%
effieient, ACME between 40 and 65% and standard 60 thread is around
30-35%.

in other words, if you can move the ballscews underload with a 150 oz-
in stepper, you would need a 450 os-in to use a 60 degreee thread.

Also, if you use standard threaded rod, it is not smooth, but cut so
the threads are even worse. if you buy ground rod so you get smooth
threads you are close to the cost of an ACME.

extensive details are in the archives somewhere.

Dave