Proximity sensor too low?

Last time I re aligned the proximity sensor I took a credit card to measure the distance as this was suggested. I tested the thickness with a digital gauge and all the cards I have are just 0.83 mm.
Since that I’m having severe problems with printing. I could hardly get any filament to stick to the bed. Only adjusting the Z-offset worked at lat. With a Z-value of -0.35 mm I was able to even print a test cube in the center of the build plate. Yesterday I was facing the problem with non adherence even at -0.35 mm. After setting the Z-offset to -0.50 (!) I was able to print a basic string test in the center of the build plate.

I then started a pattern test running overnight which was a mess…

Is it possible that I set the proximity sensor too low?

Hi… I had a problem with non stickiness too. When I import the go code… BEFORE starting the print I tried upping the heated bed temp… got it to about 90 and then found it would stick. Try it. Are you using an enclosure ? Mine is now in an enclosure with the door closed. . I think this helps keep the temperature more constant…

Sounds like you have the sensor about the right height. During auto calibration it needs to be low enough to sense the bed and stop the Z movement to prevent the nozzle hitting the bed. It needs to be about 1mm higher than the nozzle so that when printing it doesn’t hit your model.

The sensor is not used to adjust the nozzle height, that’s the bit you do as the last operation of calibration. The sensor is used to sample the height of the bed at the points around the work area in an attempt to compensate in software for any irregularities in height.

Unfortunately as the bed heats up it can move around a bit and so the cold calibration is not as useful as it might be, there are quite a few threads on the forum discussing this topic.

Setting the Z offset can have a major effect on adhesion and its quite normal to change it as the first layer is going down - preferably as a skirt or brim is being printed.


I just did another recalibration (4x4) of the bed. So the nozzle is 0.05 mm (measured with a gauge) and the sensor is 0.83 mm. The difference is just 0.78 mm. As long as the sensor doesn’t hit the model this is ok, you’re saying?!

What I’m not understanding is, first thing after calibration I was running the pattern test. To get the filament stick on the plate I had to set the Z-offset to - 0.25 mm(!) . During those print I reduced the offset to 0. Having a close look to the squares I do have the feeling that my build plate is terrible leveled.

I’ve been going through all the recommended steps very carefully over and over again. That’s really frustration. Next thing is I’ll try is a 5x5 calibration, Nozzle to 0.09 mm and putting 3DLac on the build plate.
During that print I elevated the Z-offset to + 0,10 mm (after beeing sure, filament is sticking). I think the result is much better than before. Only thing I really can’t tell is if the lines within the squares are due to the nozzle beeing too low (and leading to rims) or to high (and those lines are filament thats not flattend by the nozzle) or even if it is over extrusion (although I calibrated the extruder and confirmed it’s perfect now, with another type of filament indeed) ??

Well done!

I would suggest you to not edit the z-offset while printing (expect the first layer) because if you change too much, there could be layer separtion or bad connection between the layers.

Different filaments have different melting points and through that different flow, causing bad or good first layers.

Run the automatic leveling with a hot bed and you would get best results possible,- there are many threads in the forum about.
Connect your machine with usb to Luban and preheat with serial connection, stay connected and start your leveling from the touchscreen.

Thanks Chris! Good idea to heat the bed via the USB connection and level on touchscreen. I didn‘t know that‘s working.
3DLac is really awesome!!! I‘m totally happy with the adherence now!

How do I set the temperature? Neither M190, nor M140 are working. I do get an ok, but heatbed won’t heat?!

Go into the controls settings on the touchscreen and heat up the bed manually.
It will turn off when you exit to autocalibrate and start to cool down. I just set the temp 5-10 degrees above what I usually print at and figure it’s close enough.

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@FlyByWire, @sdj544 , connect your machine with usb and luban, now enter

M140 S80 // or whatever temperature you want 

After heating up, start the calibration process from the touchscreen.


  • You could see the probing process in the terminal while connected with usb while calibration.
  • It is also possible to set the temperature with wifi connection and Luban (You will not be able to see the probing process while calibration and you need to disconnect).

I print my most prints with 60°C bed, so i calibrate it with this temperature, but i let it preheat for 30min to let the alu substructure and the bed+sheet expand.

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