So for the last couple of weeks, I have been cutting lots of plywood circles up to 55 of 100 (maybe relevant later). But issues are arising, in 2 passes cutting 1/2 plywood with a 1/4 compression bit 8 mm/s but it looks like I am losing steps many times, and the two passes don’t line up. I did not do much investigation yet other than watching closely while the cut was happening.
At this point, I don’t think I am overloading the cutter since it only gets warm, not hot, though it could be getting dull since it was a cheap $30 (CAD) Amazon cutter.
I am leaning towards a bad stepper or maybe undersized. The reason is that when I started this job I had trouble homing Y, at first I attributed it to the wide temp swing between when I last ran the primo and now I figure something shifted with the temp swing causing the binding.
But as it happened one of the stepper motors was binding part of the rotation is fine then it hits a spot and it takes lots more pressure to finish the rotation. I am assuming that binding is not normal but how free spinning should a stepper motor be vs a standard electric motor?
Has anyone else seen this in their stepper motors?
I don’t have much to say about the stepper issues, but I wonder about the compression bits? I know that many issues have stemmed from people using a wide variety of bits, and the answer from Ryan (and others) are the single flute up cut is the way. But what do I know
In the hundreds of times I’ve seen lost step issues listed on this forum, I only remember two times the issue being a bad stepper, though bad steppers were often proposed as the suspect. Steppers are simple and are very hard to damage. With that said, if you are running your test on the motor alone (no pulley, no belt, etc.) you should have consistent rotation through the 360 degrees no particular binding or resistance. There is a bit of “graininess” when rotating the shaft…like a very fine rotary encoder.
On the other hand, if you are testing this stepper in place, then there are other things you should check out.
Historically, the grub screws on the pulley have been a common source of lost steps, and they might behave like you describe.
Bad belts can cause issues. If steel reinforced belts are used, the steel does not make the turns well and breaks, resulting in uneven teeth spacing.
Mechanical binding is also fairly common and might be selective for a variety of reasons.
Grub screws – were good, since I could not get the pully off of 3 of 4 motors (all I have had time to replace) locktite must have run. I will double check but I am 99.9% sure the belt is fiber. One more of the motors I pulled while not as bad as the first one is more than gritty. The last motor left is suspect, when I manually that axis the movement is not smooth. When I manually move the axis with two new motors it’s way smother than it ever was.
Just so some other ideas could come along. I know you say you are checking heat, but if you have too high or low amperage on the new stepper drivers this can happen also.
Hey, what is your set up? Wasn’t there something recently with Fluidnc if you were using certain drivers and they were at a certain level of microstepping?
