Eratic bed leveling

I just placed some thermal past on the heat break in an effort to combat clicking and slipping of the extruder. Because of that I also did a full re-calibration. Bed leveling measurements are very chaotic and all over the place making the procedure almost impossible.
Could this be due to the thermal paste? Is the heat break part of the electric circuit? XY calibration seems to going fine.
Any ideas?

I have had similar behaviour on some SJ1 hotends, even “virgin” as from factory. There should be good electric contact from tip of the nozzle all the way down to appropriate contact plate on small PCB on hotend. I am not by machine now but if I remember right it was the first contact from left if you keep the hotend upwards as installed into printhead. I don’t know what is actually limit for contact recognition circuit to function properly but if resistance from tip of the nozzle till contact on PCB is below 0.5 Ohm, bed levelling and Z-offset works fine. If there is no proper contact, the reading is either shifting very sporadically or (if there is no contact at all) nozzle will heavily dig into datum point of bed levelling and even leave a undesired dent there. I had this with brand new hotend right from the box.
Boron nitride paste itself is not electrically conductive and can make a good electric insulation from heatbreak to heatsink but usually still there is some dry spot which makes electric contact anyway. Four bolts that secure fan and PCB to heatsink should make electric contact from heatsink to PCB as at least three of them have contact pads under the bolts. It has happened to me contact has been lost there. Might be necessary to re-tighten them or clean PCB pads around the bolt holes from both sides of PCB.
If you have access to multimeter you can check where electric contact is lost in chain ContactPad_onPCB - bolts - heatsink - heatbreak - heatblock - nozzle.

Well it appeared to be some burned filament residue on the tip of the hardened steel nozzle. Causal brushing with it supplied brush apparently wasn’t enough. After a firm brush (copper brush) the leveling procedure was successfully.

Good to hear! Still the same about poor electrical contact :slight_smile:

Paul Gerlach via Snapmaker where creation happens <> (šajā datumā: Pr, 2024. g. 15. janv. 11:13) rakstīja:

Yeah now the issue of bad prints. Bad layer lines but the calibration vibration test prints looks fine. So I suspect is has something to do with retraction. I’m very disappointed with the extruder of a printer in this price class. My old Sidewinder X1 with Hemera extruder outperforms it.