Re: [CAD_CAM_EDM_DRO] doubling resolution strategy # 2

Ian Wright wrote:

> Hi,
>
> This is something I have been fighting with for the last couple of days. How
> DO you check the accuracy of either cnc or dro systems to the accuracies we
> seem to be capable of?
>
> . Then I commanded a
> move of 100.000mm and re-measured - it gave me a reading of 100.02mm. So, I
> sent it back to 0 and rechecked - it read 0.00 - good. I did this a couple
> of times and it all seemed Ok. Now, I thought, I wonder how accurate it is
> on smaller moves? So I fitted a metric dial gauge to the end block and moved
> the carriage to just touch it. Then I commanded a move of 1.000mm - the dial
> moved to 0.900mm exactly!! Sent it back to 0 - it now read 0, sent it to
> 1.000mm, it read 0.9mm - damn! This was getting frustrating. So, I decided
> I'd try the digital vernier again and fixed one leg to the end block and
> clamped the other to the carriage - now that must be accurate! Sent the
> carriage to 100.000mm - the vernier now read 99.75mm - back to 0 - it read
> 0. Sent it to 50.000mm - it read 49.68! still perfectly repeatable back and
> forth.

It looks like you have about .25 to .3 mm of backlash. You need to come up on
each measurement from the same direction to eliminate backlash from any
measurements.

Jon