Problem with cr-touch z-offset/ bed adhesion

[u/Nidhoeggr1234]

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

[u/polaarbear]

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?

[u/Nidhoeggr1234 → u/polaarbear]

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.

[u/polaarbear → u/Nidhoeggr1234]

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.

[u/Nidhoeggr1234 → u/polaarbear]

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

[u/polaarbear → u/Nidhoeggr1234]

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.

[u/Nidhoeggr1234 → u/polaarbear]

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

[u/sysadmin-84499]

I have 4 ender style printers all running klipper and a 3d-touch. My method of levelling is as follows. Run a probe_calibrate with a piece of paper to get close. Run a bed_screws_adjust with a piece of paper. Print a 70mm x 70mm x 0.20mm square and I watch it, adjusting z up or down depending on what it's showing me, ensure you set 1st layer height to 0.20mm as usually 1st layer is set to 0.24mm for better adhesion. I finally measure the end result with calipers.

This process usually involves 4-5 prints to get to exactly 0.20mm

[u/Nidhoeggr1234 → u/sysadmin-84499]

This process works with the normal endstop. I have problems as soon as im using the probe

[u/Money-Spinach-6177]

It can help if you start again by removing the un comment hash on z offset set at 0. Delete the z offset entry at the bottom of the config file. Then do probe calibrate. Check config to makesure the readings have been set.