BLTouch misses random probe points
August 15, 2019 03:32AM
Hi

I have just started using a BLTouch 3.0 on my Ender 3 Pro. I followed Teaching Tech's guide to installing it and the Marlin 1.1.* method. I did not remove the capacitor on the Creality board. Every so often (I can see no pattern) during ABL the probe will retract before reaching the bed and then carry on the normal probing of other locations. This can lead to some interesting mid-air printing!

I use Cura 4.1.0 to slice and the start Gcode is from the Antclabs website:

M280 P0 S160 ; BLTouch alarm release
G4 P100 ; delay for BLTouch
G28 ; home all
G29 ; auto bed leveling

I tried messaging Antclabs but no reply yet (about 2 weeks).

Has anyone encountered ths problem and found a solution?

David
Re: BLTouch misses random probe points
August 18, 2019 04:49PM
I used the BLTouch V3.0 on my Ender-5 with the Creality board with the Marlin 1.1.x version. I had to add some additions to the Marlin source at the time because V3.0 wasn't working with the stock firmware, but once I added these additions it all worked out perfectly.

I did run into something similar to what you describe, but in my case I sometimes had an air-bubble trapped between the magnetic build plate and the magnetic Z bed. As long as I made sure the magnet was securely down without a bubble, I never ran into air printing again.

I didn't have any special code for my start g-code. I was using Cura 4.0 with the BLtouch, and only had the G28 to home and then G29 to probe. I didn't have any M280 like you have on any of my start code.

I've since then replaced my Creality board with the Duet 2 Maestro, and even on that board the air-bubble can cause it to air-print every so often too.

Edited 1 time(s). Last edit at 08/18/2019 04:51PM by PDBeal.
Re: BLTouch misses random probe points
August 19, 2019 06:33AM
Thanks for that.

I do not think that air bubbles are my problem as the probing fails well before the BLTouch gets near the bed. However, I will give it a look and see if that is it.

Thanks a lot.
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