Best posts made by Gary

Problem solved! This has taken months. I checked grub screws, belt teeth…. I had noticed that now and then the hot end juddered when moving to position, but not all the time. The person I bought the machine from had cable tied the hot end cable harness to 1 of the Z motor arms. It was hanging loose and tidied up the harness, as it does tend to flop about on my other machine.
When close to the bed (within 10mm) and only in specific positions it held the arm causing the belt to slip! Also G29 failed most of the time as the probe was not triggered due to the arm being held back. The judder now solved, G29 completes and bed leveling showing a decent graph.
Thanks for your help. (I have learned lots of G code and Duet wiring though)
Gary

Hi, Sorted at some point the X belt had twisted with the non-toothed side running on the stepper. I didn’t even notice when checking the stepper grub screws. I couldn’t see the belt twist as it’s slightly recessed on the machine, but I noticed when looking closely at the carriage and tabs. Really noticeable when you manually move the carriage up and down. It makes sense now as when I did a HomeDelta quite often, but not all the time, the interface would report not all axis homed and they weren’t. I just thought it was an annoying “feature” that would sometimes happen and I would have to click Home again. The board was turning the stepper the 490mm distance I have in my HomeDelta and not triggering the end stop giving the error. Also when doing probing from high up the results were inconsistent – belt slippage. Down low with slow probes it was okay. After a Home the X and Y values were not zero on the interface and when touching bed the hot end was not centred on the bed. Now to change the belts and somehow fix the bed which got smashed at the edge when the Perspex lid hit it!
M665 L440.000:440.000:440.000 R226.630 H455.788 B185.0 X0.093 Y0.750 Z0.000
M666 X-0.012 Y-0.045 Z0.057 A0.00 B0.00