Mesh bed leveling - extruder goes up on 2 points - normal?  

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

Another question might be along the line of does it get better or worse when doing five samples rather than the default of three?

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

First thing I'd try is putting the printer on a solid floor. Resonating vibrations can trigger this -- it's detecting unexpected variances between fast probes -- and going by the thunderous sound from that video, it sounds very possible you're picking up vibration from the surface the printer is sitting on. When the fast probing was first released, the firmware initiated a Z calibration whenever this occurred. The pause and retest is a feature designed to let vibrations die down before probing again. The pause itself is normal and if you're getting good prints, nothing you need to worry about. However, the fact that it's occurring combined with that noise is definitely something I'd address as vibration can add to print defects. A solid foundation for the printer is important.

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

@bobstro

Interesting,  I have my MK3S mounted on a 70 kilo paver which should be adequate.  My double probe started after 2 months.  I will check the number of samples value as I believe it is set to 3.  I will also recalibrate after I upgrade to 3.9 FW.  Thanks for the reassurance that the real proof is a good print, that helps me.

As for the other question about the PINDA operation, Chris over at Chris"s Basement steered me to this site wrt sensor precision. 

Still don't know how the inductive sensor works but I'll keep searching.  Thanks for your time. 

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

That should be 17 kilo paver, I doubt I could lift 70!

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

Was wondering about that! I've got mine on a 17x17 inch paver as well. If it's still doing the slow probe, do check for any stray filament dangling from the nozzle and any debris between the removable sheet and heated bed. Check to make sure nothing is physically blocking any of the mechanisms or cables. I once had a thermometer positioned so the X assembly would bump it in certain positions. 

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

@bobstro et al.  Just to followup on other suggestions I tried turning on the Mag Comp and doing 5 samples to no avail. 

I would note that both sides of my plain and texture sheets have been tried and found wanting. 

I'm going to leave it alone until I upgrade to 3.9.0 and then do a full calibration.  Like Bob said, it's not doing any harm to my prints. 

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

Just to finalize my interest in the inductive sensor I found this article on the Web. 

https://electricalacademia.com/motor-control/proximity-sensor-working-principle-inductive-proximity-sensor-capacitive-proximity-sensor/

I'm satisfied with the details in this article. 

Didn't find a way to edit my previous posts so just used the reply toggle. 

RE: Mesh bed leveling - extruder goes up on 2 points - normal?

As a belated extra data point on the 'double tap' topic, this week I am doing a fairly large project which uses both PLA and ABS.

I've found that when I change from a PLA filament to an ABS filament, often, but not all the time, I get one double-tap on the left toward the rear, after letting the thing heat up and stabilize to the ABS temperature.

I'm assuming here that it's some kind of slight dimensional change due to the higher temperature.

When I go from PLA to ABS I'll always preheat, and then let it sit and stabilize for 15 minutes or so before I launch the print.

Strangely, when I go from ABS to PLA, again letting the new temperature stabilize, I get almost no double-taps.