Z adjust keeps decreasing after each use
I'm not sure when they started, I took a break from printing for a bit and just decided to fire up my printer this week. On newest firmware 3.8.1, so I kept having an issue where my first layer wasn't sticking and I noticed the first layer kept getting less squished after every print. So I redid the first layer cal and it was fine. Go to print again and it's back to where it was before. Do it again, same thing. Look online and saw a few topics where people were having this issue several firmware versions ago, so I rewrite the 3.8.1 firmware and do a full factory reset and redo the wizard. Get the first layer looking good, go to print, no dice it backed off the plate again. It's almost like it goes to this hard coded position away from the plate after every time I adjust it because stays close enough to lay down some filament, but not where I had it when I calibrated it. I start off getting a nice good first layer at about -.8, but end up at -.15 before long after each adjust and it still about the same distance from the plate after each cal. It's driving me mad. Anyone else have an issue like this? Could it be my pinda probe or is there another firmware I should try?
RE: Z adjust keeps decreasing after each use
Your problem is not related to firmware or PINDA. In order for the filament to stuck well to the bed, you should clean it with detergent and warm water. Wipe with paper and then do not touch the surface with your fingers. Cleaning with alcohol does not help, and you should definitely not use acetone.
Bear MK3 with Bondtech extruder
RE: Z adjust keeps decreasing after each use
Yeah that doesn’t solve my issue. You know how you can squish the filament by using live adjust to set the nozzle distance. Well I can set mine up to over squish and the nozzle will raise on the next print and not be over squishing anymore and it won’t be a good first layer. So I redo my first layer cal and it back to over squish, next print it is too high a first layer again. Rinse and repeat and the first layer setting keeps going down.
RE: Z adjust keeps decreasing after each use
If I understand you correctly, you adjust the Z level to make it a good first layer. But if you turn the printer off and on again, your fine setting is gone. Have I understood you correctly?
In this case, you will need to perform a new calibration under the "Calibration / Calibrate Z" menu. Once it is stored in the printer's memory, you can then use "Live adjust Z". Then your fine-tuned Z level will be saved to the next start.
Bear MK3 with Bondtech extruder
RE: Z adjust keeps decreasing after each use
Ok, so here is where I am at currently. Did a factory restore and and flashed 3.8.1 firmware to start fresh. Did the wizard and first layer cal was at like -.8. Good squish and everything looks fine. First print after wizard and cal, print isn’t squished enough To the point where there are big gaps between each run across, it’s barely sticking and won’t stick once it starts going up in layers. Redo first layer call, new z adjust is at -.95 or something, good squish. Go to print, same thing as before. Redo first layer cal, -1.1. Go to print, bad first layer. This time instead of doing first layer. Drop it to -1.25 in settings, prints fine. Print again, bad first layer. If I leave it on bad first layer and redo the cal, it stays at that point. It doesn’t continually keep backing off. It likes to go back to that position for some reason.
RE: Z adjust keeps decreasing after each use
I clean my nozzle every time and keep the bed clean too. Nozzle and pinda are both tight. Nothing loose or moving around that I could find. Belts and their tightness numbers look good.
RE: Z adjust keeps decreasing after each use
I think this was happening to me also. I thought I was going crazy. Then I thought that maybe the POM bearings I printed were the reason that the tolerance kept changing. I will be interested to see if you can get this issue fixed.
RE: Z adjust keeps decreasing after each use
Check the pinda probe mount, did it get damaged?
Most other printers I'd say check the Z motor couplers, but Prusa doesn't use them. But you could check if the little plastic "covers" on the threaded rods are not screwed down tightly against the motor bodies and causing resistance on the Z motors.
There is a menu screen that shows all the temperatures including the pinda probe, see if that is reporting a reasonable temperature. If everything is fine mechanically it sounds like the probe is not compensating for temperature correctly, seems like as it warms up the trigger point is changing.
RE: Z adjust keeps decreasing after each use
Yeah checked the pinda probe mount because I had a mount melt on a previous design I had, went back to stock. That was awhile ago though, not a recent change. This one looks fine, checked distance several times like the manual says with the tie wrap and it’s holding steady, no movement as far as I can tell.
Will have to check the temps.
RE: Z adjust keeps decreasing after each use
Issue finally revealed itself. It was the part cooling fan duct. It finally melted enough to show me what was going on. Once I removed it and did some first layer tests, it worked fine. Must of been loose and causing issues of some sort.