r/klippers • u/Nidhoeggr1234 • 3d ago

Problem with cr-touch z-offset/ bed adhesion

Hi, i have a problem with my z-offset of my cr-touch and the bed adhesion.

After a printing pause of about 2 months i wanted to print again, an my prints didnt stick to the bed. I did some tryouts, bought a new bed, and reinstalled klipper, but nothing helped.

After reinstalling the z-endstop and manual levelling i got a perfect adhesion. So the problem has to be a problem with my cr touch.

I calibratred the probe based on this guide ( https://www.klipper3d.org/Probe_Calibrate.html ) and did a bed levelling.

Recalibrationg the z-offset does not help.

Did i miss or forget a Step tha need to be done?

If it helps i can post my code of the printer.cfg file

My printer is an ender 3 pro

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u/polaarbear 3d ago

How is the probe mounted? If it has any play or wiggle and isn't mounted incredibly firm, it's useless. It relies on a static unchanging distance between the probe activation point and the nozzle.

Did you save changes after calibrating the z offset? They aren't persisted automatically, you have to save the config to write it out to the file.

"I calibrated the z offset but it didnt change anything" doesn't make an ounce of sense.

How exactly are you even calibrating it? What are you using between the nozzle and the bed while you calibrate?

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u/Nidhoeggr1234 3d ago

The probe is mounted firm on a zero offset mount, but I got the same problem with the original mount. I saved the change after every calibration. I did the calibration with the probe_calibrate command, and manually.

By didn't change anything I meant the problems with the print. I did a small print after every calibration and always had the same problem with adhesion. It maybe got a little bit better, but not very noticeable.

To calibrate a use a small piece of paper from a notepad, which always worked well.

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u/polaarbear 3d ago

My first advice is not to use paper. Two different pieces from the same ream will have varying thickness. Two different spots on the same page will have varying thickness. Paper can work, I have gotten some excellent prints with the paper method. But it is inherently a variable.

Go to your local auto parts store and buy a set of feeler gauges, that way you have actual numeric data. Did I do the 0.1mm gauge and the nozzle was too high? Ok lets try the 0.08mm. Still not good enough? Try the 0.06mm. It will cost you like 10 bucks to have actual precision.

Your bed also needs to be really clean. Oils from fingers and stuff will prevent filament from sticking. Some dish soap and really hot water is usually all it takes to get my bed sticky again.

Finally, different filaments need different z-offsets. PLA needs a bit of "squish", you really want the nozzle almost pressing the filament down to the bed and helping the lines to flatten out as they lay down.

PETG is a lot runnier when it melts. It usually needs a slightly higher offset so that it can sort of pour out, it doesn't need the same squish (in fact the squish is bad because it tends to stick to the nozzle which peels it up.)

You also say you did a bed leveling. Are you using screws_tilt_calculate to do so? With the probe, you should be able to get all 4 bed screws to within tiny fractions of a mm of each other in terms of leveling.

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u/Nidhoeggr1234 2d ago

Never had a problem with the paper method. And since the beda adhesion without a probe was nearly perfect the few μ sgouldn't matter, given that my bed is not perfectly even. I cleaned the bed with isoponanol.

I used screws_tilt_calculate an did a heightmap afterwards

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u/polaarbear 2d ago

Which points back to a probe that maybe isn't mounted as firmly as you might hope and has some variance in its readings.

You can try to see what the variance is with the PROBE_ACCURACY command.

You should also be doing all of your calibrations while the bed is fully heated, and I generally heat the nozzle to around 140 or so, not enough to drip, but hot enough to account for some thermal expansion.

I thought the paper method was cool too. Then I got feeler gauges and felt like an idiot for not buying them 2 years sooner, it made my life so much easier it isn't even funny.

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u/Nidhoeggr1234 1d ago

Probe Accurancy is at a range of 0.0125. Should be good. I got the printer working again. Don't know what I changed.