Re: leadscrew, acme screw, threaded rod, ballscrew

"Ross" <rrcarl@n...> wrote:

> "Leadscrew" could refer to either of the three, though I would not

expect to see threaded rod on even a half decent CNC machine.

So leadscrew is not a special form the threaded rod that one can
purchase from any hardware store? So the leadscrew in the respectable
Sherline is a threaded rod?

> Acme rod is usually what you see on low/mid range machines. It

comes in different levels of linear precision and it is fairly
inexpensive. I think I paid $13 for a 6 foot length of 5/8x8. Anti
backlash nuts are available for acme rod, but I'd saty away from the
plastic nuts on a larger machine. They are quite expensive ($30
each). They didn;t last very long on my large table. I went to
bronze nuts and have had no problem.

> Ball screws are quite expensive but offer less turning resistance

and more accuracy than acme rod. It all depends on how much you want
to spend and how accurate your machine needs to be.

I see that acme screw is a kind of square thread. But I see also ball
screw using square threads. Are these acme screw? So is the
difference between drives using acme screw and ballscrew existing
only in the type of drive nuts they use - with the ballscrew having
recirculating balls?

Al