Re: [CAD_CAM_EDM_DRO] Re: re:OK - you convinced me - was "Automated "Manual C...

In a message dated 10/06/2000 4:28:55 AM Hawaiian Standard Time,
bcollier@... writes:

<< I am a little confused when you talk about backlash being a problem
in my proposed set up. In open-loop or closed-loop with position
feedback from the motor, I understand about backlash being a problem.
The PC has no way of knowing the true position of the workpiece due
to the backlash. However, with closed-loop with feedback from the
table, couldn't the CNC program just work around it?

>>

Brian,

All the backlash comp in the world won't help you if a two flute endmill
in steel is causing chatter. You would have a very hard time climb milling.
Even if you were able to eliminate chatter by applying lots of drag an your
slides, the short dwell the cutter would experience while the leadscrew takes
up slack in the opposite direction will give you a "shiny spot" if not a
divot in the cut surface.

You are correct, if you have feedback and really tight ways, you will have
very close to perfect positional movement, you most likely will not have good
velocity control. This will make a big differnece in your surface finish. Not
to mention tool life.

Peter
THRD, Inc.

PS, What drives your desire to do it this way? Cost? Limitations of machining
facilities?