Re: [CAD_CAM_EDM_DRO] Re: Climb Milling (again)

This is fine...provided the machines backlash forever remains constant.

However...in the case of wear or an overloaded condition which caused the
machine to j"jump" the software is useless as the software would have no
idea how to comensate for chages that took place while the machine was
running. You'd have to stop the machine, recheck the backlash and reset the
software.

As for the "jump" due to overloading..I've seen this happen in practice on
manual machines. Haven't tried it on the CNC machine at school...I think
they'd frown on that a little bit!

Smoke

>A value for the backlash or "reversal" compensation for each axis is
>entered manually into a table in the controller. The value is pre-
>determined by the operator or machine installation tech. A value of
>acceptable accuracy can be determined with nothing more than an
>accurate dial indicator, sometimes a method of putting a repeatable
>load or drag can be helpful, too. On systems with a great deal of
>wear the actual value of the compensation factor would be different
>at different positions along the lead screws. In that case you would
>have to choose an acceptable average value and live with it.
>
>Also, it seems some here are thinking in terms of large amounts of
>backlash. When I got my biggest mill it had pre-entered values of
>less than .0005" for X,Y,Z from the factory. Since the X table on
>that machine must weigh well over 500 pounds it's hard to imagine any
>cutter could make it "jump" under normal conditions.
>
>thanks,
>
>Doug
>
>