BTW, the error corrected by retuning was less than the amount that would cause a fault, so maybe it isn't so surprising. I found that surprising given it is closed loop, but it was the case. If you have servos (not steppers), tuning will affect your accuracy, at least on my system. Zvika, these things are always a bit of detective work, but we learn something interesting each time.Ĭircles are absolutely the hardest 'torture test' for these machines. This new finding can't fully explain the original problem since the pockets diameter is fixed and it is not an ellipse. I'll try to verify it with a dial indicator. It can be a DRO problem but it can also be a problem with the screw. This is another strange problem that I can't explain yet. At a very specific point (of the X axis), When the table crosses this point, the DRO readouts jumps 0.1mm. I've continued investigating it and I may have found the problem (actually, by accident). Further more, I think that the step/movement ratio is also correct since when I move the table for a large distance, the DRE readouts are matched.Īs I wrote, I couldn't find any logical explenation for this strange problem. In addition, I don't think that it is a backlash issue since the backlash is cancelled by software and it seems to work well. I think that my measurements are correct (I verified it). Unfortunately, I already went through most of your suggestions. Your willing to help and your very smart advices is admirable. Learn how to apply tool offsets in the cnc control to compensate for tool wear or part out of tolerences when machining.įirst of all, Matt, Mike and Superman, thank you very much. 01mm (.001') or less, making adjustments is part of being a machinist. Small variations can be caused by using a caliper instead of a micrometer to measure the end mill, machine flex or endmill flex. 001' move and it will match the indicator for full 1' travel of the indicator. My machine should have bben 20k steps per inch based on what I thought I had, but I needed 21937 or some such thing to make Mach3 give me good readings on the dial indicator. If you have set them up based on the mathimatical values of the steps per rev and the tpi of the screw or their metric equivilents, you can sometimes come up short or have the wrong values.

Using a good dial indicator, I would verify that the dro and the computer are actually calibrated correctly.

Backlash in the system normally results in the circular feature being out of round at the compas points.

Mastercam pocket milling