UM3 BB 0.4 Core Scrapes Glass

[polygonfuture 0]

Hi all,

 

I am having a problem with my UM3.

Today I replaced my short belts and the short bearing the print head.  After reassembly, I loaded my AA 0.4 print core into slot 1, and BB 0.4 print core into slot 2.

 

After printing a simple cube using PLA test from core AA, I went to print something that used the BB core with PVA.

 

After doing the prime blob, the BB print core began to "print", but it appeared to only be scraping off the glue stick off of the glass.  When the bed retracts, some PVA extrudes out.

 

I have ran active leveling, and finally manual leveling and each time I keep getting the same result for my PVA adhesion layer.

 

I have ran diagnostics on my level sensor, and UM3 is saying it is functioning ok.  I have also tried to clear the print head using PLA filament and the cleaning routine.

 

Any one have any ideas why this is happening?   What could be causing this?
 

[polygonfuture 0]

Ok, so scratch that.   Both cores are scraping the glass and not printing.   What the heck.  I dont understand.

[polygonfuture 0]

Ok Ultimaker Community.

 

It appears I may have found a bug with UM3 5.2.8 firmware!

 

If turn active leveling frequency less than "always", the machine appears to fail to remember the offsets, and print at the wrong z height.

 

The moment I turn active leveling frequency back to always, it prints at the proper z offset from the glass plate.   Not on "always", the printer prints at the absolute 0 Z cordinate as the glass plate, therefore it can never extrude.

 

Can anyone else replicate this?

[Dim3nsioneer 523]

It worked for me too with "every week". The only setting that IS different is "Never" which now turns active leveling completely off (to be manually leveled properly).

[gr5 1,472]

I *only* use manual leveling.  Once set, the leveling doesn't need to be messed with for months.

[kfsone 5]

See my reply here: 

 

- Make sure you check the print core, under those soft-white tabs ... and on the back of the heating element, make sure you don't have gunk;
- Don't mix manual and auto;

- "Some resistance" is a really terrible description of what you are looking for 😞

 

[SunnyJames 1]

I have this exact same problem with current firmware.  Active leveling set to always works as expected.  Leveling set to weekly (my preference) results in print cores which impact and scratch the surface while printing.  This is clearly a bug. 

[kfsone 5]

I've been noticing "random" behaviors. The other day I did something routine and it suddenly started unloading printcore 1. @gr5 told me there is an issue preventing printing the calibration chart because the printer over-retracts print core 2, but then support told me that he's wrong, the bug prevents anyone printing a calibration chart. Except, I've been able to print a calibration chart by doing nothing more than print->power cycle->print. I was able to print once and then it lost the calibration (even tho it has the settings). With active leveling set to manual, it will occasionally still do active leveling on me. There's just this long list of weird things the printer has been doing since the last firmware.

 

I know I could downgrade, but physical, forced, firmware kludges have bricked too many devices for me in the past, and I can get about 70-80% of the prints I want with single extrusion, and I haven't seen any kind of disclaimer that if I brick my printer following the firmware recovery instructions I won't be out of warranty...

 

@SandervG I'd rather than they put the old firmware up on the testing channel and let people choose to "up"-downgrade to it.