Machine movement calibration

[PeteJ]

Trying to get the machine movement calibrated and am struggling to understand what setting to adjust. Attached a picture showing how I am measuring movement in the X. When I jog the machine 2" in the + the DRO indicates 2" but the table only moves 1.997". When doing this I made sure to remove any backlash in the system.

I have done this multiple times and it repeats.

I have attached pictures of the setup I'm using to measure as well as the motor configuration setup. These are the values imported from the system prior to the upgrade.

[Nigelo]

For a commanded move of 2" inches but actual travel of 1.997" with motor revs/inch currently set to 9.9991 try setting Motor revs/inch to 10.01412118 Save and then re-home before retesting

This assumes your actual measurement is correct and you have indeed excluded backlash by pre-travelling in the same direction as subsequent measurement. If you reverse direction at any stage, all bets are off of course

[Centroid_Tech2]

https://www.centroidcnc.com/dealersuppo ... ads/36.pdf

"Imperial - How to calculate motor revs/inch:
Commanded distance / Distance moved = multiplier
Multiplier * Current revs/inch = corrected revs/inch
Ex: Commanded Distance = 6.0000” = ~.999417 (multiplier) * current revs/inch
Distance moved = 6.0035”
(multiplier) .999417 * (current revs/inch) 5.0000 = 4.997085 "

[PeteJ]

For a commanded move of 2" inches but actual travel of 1.997" with motor revs/inch currently set to 9.9991 try setting Motor revs/inch to 10.01412118 Save and then re-home before retesting

This assumes your actual measurement is correct and you have indeed excluded backlash by pre-travelling in the same direction as subsequent measurement. If you reverse direction at any stage, all bets are off of course

This is the part that is confusing to me. I came up with a similar number and thought I was doing the math wrong. I tried it again and it is actually got worse. It is went to 1.995 and it would not zero when I brought it back. The results were getting more inconsistent.

I believe I found the issue. I was using the wheel on the wireless MPG-6 to move the table and noticed that it is very speed sensitive. If I move the wheel too quickly it would not move the proper amount, as if it was dropping signals.

I reset the rev/in back to the original values and used the on screen controls and the DRO matches the movement of the table.

Anybody experienced similar issues with the wmpg-6?

[Nigelo]

No, you do not "bring it back" at all and should not be using the wmpg to conduct these tests. Use mdi for the pre travel to your start point and set WCS X to zero. Read off your dti or set to zero and then use mdi again to move to X2 in the SAME as direction as pre travel at say F8 I.e G1 X2 F8. DRO will now read 2.000 and so should your dti. If not, do the math and rinse / repeat. That is it for calibration

To return to zero requires backlash to be set properly AFTER calibration has been correctly fine tuned and that's a completely separate exercise.

[NeilS]

You also need to be really careful on your DTI set up to avoid Cosine error, what you have is far from ideal having the DTI tip on the spindle, any angular misalignment of the gauge from the true x Axis magnifies the error using a radius target. Best practice would say mount the DTI to the spindle and clock to the vise having made sure that it is in tram and that the DTI axis is parallel to the X axis.