I have steps per rotation dialed in on my piburn. It will rotate back to my mark when commanded the circumference of my tumbler once, but if I command it to do another rotation to check repeatability, it only moves maybe half way. What am I missing?
New omtech 60w MF-1624, piburn v4. Newest updated lightburn, problem exists on usb and Ethernet connection.
TiA
There should be no ‘dialing in’ of the steps/rotation. This is something that the stepper drivers are configured and set. Maybe this is the problem…
What are your settings for the PiBurn and how did you come up with them?
It should rotate 1 full turn and return…
A wheel rotary does not rely on circumference.
Do you have this setup as per the manual from PiBurn? I have a 3.0 version model.
I have the piburn V4. I did set it up following piburn instruction manual, speeds and acceleration rates included. I understand circumference setting plays no role in the setup. I mention circumference since I am commanding lightburn to turn the rotary the circumference of my test piece which would bring it full circle. Setup for my rig was supposed to be 5000 steps per rev, but that overshot my starting mark. I ended up using 4715 steps per rev and it repeatedly hit my center mark after full rotation. I shutdown and restarted my laser and computer and the odd issue of inconsistent movement seems to have gone for now. One issue I’m still having is that if I run a power test grid on a tumbler, the grid slowly skews out of square. When the rotary reverses direction to go back to start it is not moving far enough. The best I can tell, the cup is not slipping, it is clamped inside and has the end roller in place as well. Rotary speeds are at 30mms. Thoughts?
Sounds like mine, steps/rotation is 2000 and the ratio is 2.5 = 5000 steps/rotation.
IMHO these should not change… This is through the digital path and it needs to be correct.
if you have any adjustment, I’d suggest it be the driving wheel diameter that you ‘fudge’ with as that’s probably where the error is. Have you measured it? Mine was off 1mm.
Use the test button on the rotary gui…
X or Y? What’s I find to be the issue is the Y axes acceleration values. Mine are down in the single digits with the rotary. If it accelerates too fast, that’s where it will slip and it’s so quick and usually a minor amount, you can’t see the mug ‘jump’, but it’s obvious from the art that it did.
I have about three rotary configuration files, depending on what I do. I have most of the Y axes slowed down.
I’ve changed my steps back, and as you suggested modified wheel dia. To tweak my setup. So I can command it full circumference in one direction and it will mail my line repeatedly, however, if I roll back 1 circumference the other direction, it is off roughly 1.5mm
When I try to change y engrave acceleration, it puts it back to 2000
You need to ‘write’ it back to the controller after you make a change.
Can’t see this happening, except for a slip or something. The motor will take the same amount of steps in the other direction. Has to be something between the motor and the mug.
I believe you are correct. I tore my setup apart and found some painters tape glue residue on the part stop. I cleaned that off, made sure there was no overhang on my tumbler and also cleaned the o rings on the drive wheels with alcohol. After all that I was able to fudge my wheel diameter and got it very close repeatability in both directions. Just goes to show, this tiniest of details can make or break the process.
Thanks for your assistance, I learned a lot.
We’ve moved into a digital world. You should not have to ‘fudge’ digital equipment to ‘fix’ things. When you leave digital to analog or mechanical, that’s where the ‘fudge factor’ comes into play.
Glad you found the issue. I have also found that not making the hold downs or alignment wheels too tight will alleviate some of the alignment issues.
Good luck … post some of your work 
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