@droftarts I will change my wiring according to the new recomendations.
@JAY_S_UK i marked the pins i use
0816d776-6256-49c3-8f42-7cfbff964733-image.png

@infiniteloop Thanks for the input! Again it's been operating forever just fine, well passed useful dates most likely, so the probability of the board finally giving out under such heavy use over the years is way more likely than the 2 wires breaking at the same time, or 2 separate crimps at the same time, etc.

Any other suggestions from others?

Hoping dc responds with a magic diag code... Though I'm afraid the graph spells it out 😞
Replacing the psu would be so much easier..

Print.png

@jens55 I use a 0.7 mm thick sheet of PEI. It covers the bed plate right to the edges, as does the heater. I'm going to seal the edge with silicone once I get the PEI reglued. The only time I've had curling of the PEI is when the adhesive let go a couple years ago (a large print pulls up the PEI) and again very recently, hence the regluing that is about to happen.

When the 468MP fails on a heater you get air bubbles between the heater and plate. That results in poor heat transfer from the heater to the plate and burns the heater. After the last failure I mounted a new heater using high temperature silicone instead of the 468MP. It's been on there for at least 3 years with no issues. Keenovo sells heaters with and without adhesive.

The Rino 30:1 worm gear reducer I use in the Z axis keeps the bed from moving when power is lost. In theory, it can resume a print after power is interrupted. I'll have to put a gauge on the printer and see how much the bed jumps when power is restored. The bed moves 20um/full step of the motor, so I suspect the jump will be small. It might produce a visible discontinuity in the print (one layer too thick or too thin) but the print should finish. I usually print in 0.5mm layers with a 1 mm nozzle, so a few microns jump won't matter much. If I were printing in 100 um layers it would certainly be more of an issue.

@jens55 Hi, Can you pls guide on setting up the Pi Zero with Duet.

@SJI no, its open loop control after all.

@chrishamm

Just plugged a touchscreen into the raspberry pi, and tried to reproduce the issue. Behaviour is the same. The Duet website seems to hang. The raspberry pi is still responsive, so I think it's the Duet board itself that hangs.

@o_lampe said in Differential drive with belts (or balls or gears...):

@deckingman said in Differential drive with belts (or balls or gears...):

most steppers have a quoted resolution of +- 5 degrees per step (non accumulative)

Fact checking: It's +/- 5% per step, but still worth considering.

Sorry - I meant % rather than degrees. On a 200 step per rev motor, 5 degrees would be about 3 full steps so an error of 3 steps per step would be somewhat extreme. ☺

@paralepsis The AP died, how did you handle it? Did you get a replacement from Duet, or ...?

@deckingman thank you for your explanation 🙂 much appreciated.

@br7408 Probably the best way to do this is just to run a test print (maybe one designed to test input shaping like this one https://www.klipper3d.org/prints/ringing_tower.stl) and vary the input shaper selected and settings during the print.

Q to @ll : How would replacing the Nema17 pancake stepper change things?
I found them pretty weak and heavy compared to the much lighter Nema14 round steppers (Orbiter etc.) So either live with the slower printspeed and use a lighter stepper or go for a full size Nema17 with extra grunt.

@Ethelred
Flashed an updated PanelDue binary and all is well - gadzooks, the previous version was pre-historic.
Thanks to all for the help.

@ctilley79 no. I am running the 1HCL boards on them

@DuetWiz1122 you would set the P value to 0 assuming this is the first P output you've setup. The CAN address goes in the C part e.g. C"123.out0"

@Phaedrux

yes, was working!!!
thank you

Try printing a much simpler tall object like a hollow cube and see if it has the same skips at that height. From your description it sounds like there are overhangs in the area of the skip. I would bet that it's curling a bit and making contact and then pressing it down in subsequent layers, but without photos it's hard to tell.

Got It. Thank you very much

@Legrand, look at the bottom side of the board - it might be toast (literally).
At minimum, you need to replace both the header on the board as well as the connector on the wires. If the copper traces on the back side are damaged (that includes being heavily oxidized from heat) then you can either toss the board or you can do point-to-point wiring from a suitable undamaged area of the copper traces to the header. It might be better to have the header off the pcb (hanging off the point-to-point wiring) if the board is heavily damaged from the heat.
How this happens is if there is a connection with too much contact resistance. The current flowing through the contact resistance heats the contact and eventually you get what you see. In this case it would appear that the third connector insert from the top (yellow) was causing the issue. You could have had a bad connection between the contact and the header or, more likely, the crimp was not done correctly.