After cutting the struts, switching out the temp ones and reassembling, the gantry is no longer tracking straight. The further away from home the worse it gets. After about a meter of travel, the rail side is lagging behind the other side fairly badly (see pics). I thought this may be due to the strut plates being not being tightened in the correct position, but after loosening off all the screws, it’s still not tracking correctly.
Things I’ve tried:
verified the heal/toe measurements match (~0.5mm discrepancy)
played around with the pulloff values (I’m not sure this would actually cause it to get more skewed as it moves away from home?)
verified the lower EMT is not touching the YZ plates
verified the belts are parallel
tightened / loosened the belt tension
It almost seems like one of the steppers is running faster than the other. When returning to home, the skew is nearly corrected (but not perfect).
I would check that the Y pulleys are the same size. It sounds like one may be 16 teeth and the other may be 20 teeth. This is indicated by your comment that the gantry re-squares itself when you move it back to YMin.
Other options may be skipping steps on one side (binding or catching somewhere), or a loose wire to one stepper motor, but this would not result in the square correcting itself…
Are you sure you printed the right parts for your diameter pipes? I think the bearings should be flat on the tube. In the picture it is only making contact with the corner of the bearings. Edit; or are you tilting it? Difficult to see from the picture.
What control board are you running? If Jackpot what version of the firmware are you on. I remember there were a few versions in there that had some crazy stuff like this but cant remember which ones exactly.
Thanks for all the ideas! I should have made it a bit more clear, but it was tracking properly prior to switching out the temp strut plates with the cut ones (it was aligned enough to cut them), so something’s gone wrong between the disassembly / reassembly.
I think that rules out problems with Y pulley sizes, improperly printed parts, and control board software as there’s been no changes to those.
I’ll check for loose wires in the control box (as this did get moved to be mounted on the new struts) and give it another go hopefully later tonight.
Checked the electrical connections and they seem fine. I did some more testing and found y0 was driving 107mm when it was only supposed to move 100. Tried switching the connection with y1, and now it’s driving too far, so it seems that I’ve got a config or stepper controller issue.
I downloaded and inspected the config.yml and the y motors look like they have an identical config, other than different pin assignments.
Is there an easy way to reset everything to factory defaults?
Figured it out. There was “gunk” in the pulley on the one side which I guess was increasing it’s diameter, but still managing to drive it without skipping teeth. I must have been mistaken when I did the wire switching test.
Has anyone else experienced this? Or did I just managed to get my belt especially dirty somehow?
We have recently realized that there can be slight variations in belts, such that they have small impacts like moving a few mm off over longer distances.
Did you happen to use belts from two different lots? That can do it.
Given that bit of learning, it isn’t totally surprising to me that a dirty belt or a dirty pulley maight similarly cause slight/subtle motion errors.
