Hi, I’ve had this problem for a few weeks now and I decided to ask for a help. The problem occurs when the nozzle doesn’t seem to recognize roundish sensors attached to the corners of the bed. When autoleveling, the nozzle does not stop when it engages the sensor and it keep tries to go downward after the nozzle hits them, causing the bed bending downward. It happens quite often and I figured every time it happens, there is a weird uneven brim and ugly extrusion for the bottom layers. Any tips/suggestions would be appreciated. Thanks.
Bump up the nozzle temperature in the autolevelling G-code by 5-10 degrees. It will do a better job of cleaning the nozzle on the wiper pad (assuming the wiperpad is relatively clean). This alone as cured all my auto-levelling woes.
Look for:
M109 S140 ; set to cleaning temp and wait
G1 Z150 E-30 F75 ; suck up XXmm of filament
M109 S140 ; heat up rest of way
For PLA I use:
M109 S150 ; set to cleaning temp and wait
G1 Z150 E-30 F75 ; suck up XXmm of filament
M109 S150 ; heat up rest of way
For ABS I use:
M109 S170 ; set to cleaning temp and wait
G1 Z150 E-30 F75 ; suck up XXmm of filament
M109 S170 ; heat up rest of way
[quote=“Teddy”]Bump up the nozzle temperature in the autolevelling G-code by 5-10 degrees. It will do a better job of cleaning the nozzle on the wiper pad (assuming the wiperpad is relatively clean). This alone as cured all my auto-levelling woes.
For PLA I use:
M109 S150 ; set to cleaning temp and wait
G1 Z150 E-30 F75 ; suck up XXmm of filament
M109 S150 ; heat up rest of way
I’ll try this out and see what happens. Sounds like it should probably fix the problem because I’m having this issue only when I’m using PLA. I’ve never had this issue with HIPS filament. Thank you so much!
Does the nozzle have any build up on it after the cleaning step?
Keep a scotch brite pad and I buy the green ones at the supermarket, used for scrubbing pots and pans. Clean the nozzle when it warmed up and when needed. The pad is made of what appears to be the same plastic material used in the wiping pad on the bed. Do not use any metal brushes or the like on the nozzle when its powered.
I’ve only had my mini for less than a week now. However, my friend told me to watch the auto leveling sequence and if it pushes the bed down, abort with the power switch and recover from there.
Here are a few things I’ve been doing that seem to work very well:
When it just finishes a print and is retracting the head, use a paper towel and clean the nozzle well. It is still at printing temperature, and will clean up very nicely.
If I miss the finish of a print, and everything has cooled down, I go into Cura and manually run the nozzle temperature to 200 and wipe it clean. Then I proceed with my print, and watch it while it cools down, cleans, and touches off the 4 corners. If I see anything wrong, I abort and restart. Keep in mind if you abort and restart, you may need to extrude material back into the head using the extrude control. It may pull back too much filament and then you have to re-feed it.
I will be trying the higher wiping temperatures with PLA (thanks Teddy) since it does seem too cold. My tests showed 160 was about where it failed to extrude, which is obviously where the plastic is no longer hot enough to clean either. There is probably a point where it’s too hot for the cleaning pad.
Also, watch the tip after it cleans on the pad. I had some fibers from the pad that wanted to stick to the nozzle, and that did cause it to fail leveling. I flipped my pad over and haven’t had much of an issue since. I think it was due to cleaning with a dirty nozzle, barely heated enough, and the fibers stuck to it.
I have a small flashlight I use to look at the end of the nozzle during the cleaning and leveling process. If it’s dirty, it probably will fail an auto-level, and you might as well quit. Otherwise, you may scratch the bed or have other issues.
That post process is smart, Maybe the “wipe” portion of the start script should be implemented as a end script too.
The key would be to keep the last Z height before dropping onto the wipe pad.
After some leveling failures due to either bits of plastic left on the extruder or filaments from the cleaning pad sticking to the tip, I took the cleaning pad out altogether and now inspect the extruder with a flashlight and manually clean the tip before prints. Now I have a 90+% success rate in auto leveling.
Personally, I find that PLA is the most difficult to use successfully with autoleveling – as in I have to meticulously clean before every print and often have to make two tries at getting it to work right. PETG is pretty reliable and the nozzle only needs a manual cleaning every 5 or 6 prints. ABS is so reliable I don’t even bother watching anymore, though not watching is inadvisable and ABS has other issues that make it difficult.
I’m having this problem too with Polymax (a higher temp PLA). Since I modified the PLA profile it has used the S140 which is far too low.
Is it possible to mod the profile code to M109 S{(print_temperature - 10)} so the temp will change to suit the material?
Thanks.
Andrew
Old thread but one I found when trying to fix this problem on my Lulz Mini so I thought I’d share…
For me the problem was actually a probe temperature that was too HOT. I was using a wood PLA that was a bit runny. At the 170 degree temp set by the default profile it would always ooze a tiny bit of filament between the cleaning and one of the leveling actions, eventually causing a leveling abort. Setting the temp to 140 fixed the issue.