Re:OK - you convinced me - was "Automated "Manual CNC"

Brian Collier wrote:

>
>
> In that case, use preloaded nuts to eliminate backlash. But as in the
> question before, the inaccuracies in the leadscrew still shouldn't
> matter, right?

I dont think the inaccuracies in a leadscrew make any diference under
any conditons of 'home brew' CNC. If you are making parts where greater
accuracy than common screw threads offer is needed, you ought to be
using big money commercial equipment.

Ordinary rolled thread screw stock is usually under .003" per foot
accuracy. Ive got a good Mitutoyo caliper, and I dont read accurately to
within a few thou on large- 4-5 inch- measurements.

Be very careful you dont mislead your self on accuracy vs precision,
remember even digital watchs can have the wrong time, even if very
precisely wrong.

If I follow your thread here you are talking about a home brew system
with common leadscrews and measuring with caliper type encoders. I
suspect most screw stock is at lest as accurate, maybe better, than a
common electronic caliper.

To my view doing anything like this is a big waste- build a simple XY
table with stepper motors and get on with making parts. Unless writing
intereting software is what you really want to do.

ron