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digitalkid56
(@digitalkid56)
Active Member
Inconsistent Printing / Random Issues

First off, I love this Prusa Mini, best printer I own by far. (this is my 4th)

Main issue I'm getting started after my 5 or 6th print. It seems to be related to retraction or something.. Let's see if I can describe this (don't mind my lack of proper terminology). When I start a print, usually around layer 4 or 5 I notice it starts to print inconsistently. Right after makes 2 passes for the shell then starts filling in a solid layer. I can hear clicking like its skipping somewhere, prints really splotchy (Purple Filament pic) then suddenly it clears itself up and starts printing ok again.. Until the next layer. It happens with both Prusament and 3rd party filament. Sometimes if a layer does complete, I'll get inconsistent stripes and ridges (Yellow Filament pic), and then it'll clear up again on the next layer. If I let it continue sometimes it'll get better, sometimes I end up with a really poor sidewall, but tends to clear up at the infill levels where retraction doesn't seem to be as much? (as hard? not sure) I'll include a picture to show what I'm trying to explain into words..

 

Another side issue, after a print when I'm changing filament, I often get a Runaway Bed temp error and I have to restart the unit. This happened about 3 times so far. Kinda weird.

 

If anyone has any suggestions, please let me know! thanks!

Best Answer by digitalkid56:

** UPDATE ** 

Ok so I've tried a couple of things and it's been working so far..

- Increased nozzle temp (by about 10 degrees). Normally I print PLA around 215, by increasing nozzle to 225, it's been clearing up the sputtering and clicking for the most part. Every now and again I hear something, but can't determine if its just he filament creeking in the bowden or if it's slipping in the gearing.

- Secondly, I've been reading about loose screws in the heatbreak and strain on the sensor/cables. so I've downloaded and printed these replacement parts made by Pekcitron on thingiverse to alleviate any kind of strain. https://www.thingiverse.com/search?q=prusa+mini&dwh=55e045ff7cfeb9

 

So far everything has been going ok, will update if any other issues arise. Also, let me know if these have helped any of you with the same issues!

Posted : 23/12/2019 11:07 am
brad.w2
(@brad-w2)
Active Member
RE: Inconsistent Printing / Random Issues

Having the same issues with underextrusion. 

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Posted : 23/12/2019 12:50 pm
digitalkid56
(@digitalkid56)
Active Member
Topic starter answered:
RE: Inconsistent Printing / Random Issues

@brad-w2

Have you found any resolution to this issue yet? I’m trying not to have to disassemble this fresh build, but I feel like the issue is in somewhere in the gearing of the filament loader.

Posted : 24/12/2019 1:31 am
waltercrundwell
(@waltercrundwell)
New Member
RE: Inconsistent Printing / Random Issues

We are having issues with the print starting to "lean" towards the front like a gradual slide...Not a layer shift or anything sudden... more like a slide... We've been printing lithophanes primarily. someone suggested inconsistent heat. so we move the machine to a room where ambient heat is more constant. On one, I lowered the fan speed... but then it took off sideways again.... We have a couple of prints where it seems to slide back and forth and didn't seem to effect the actual Lithophane at all... really weird.. I need some steps to diagnose the problem and fix it.... Our very first mini lithophane worked nearly perfectly so this is quite puzzling...

Posted : 24/12/2019 2:39 am
g.j.sieben
(@g-j-sieben)
Trusted Member
RE: Inconsistent Printing / Random Issues

I think I had something like this happen with my Hatchbox PLA. It would stop printing for a little while when it started the next layer (think ~10-20 rows skipped, nothing), then it would spit out a huge blob and print normally. And it would do this for every layer (until it just stopped printing entirely and randomly).

Posted : 24/12/2019 4:40 am
digitalkid56
(@digitalkid56)
Active Member
Topic starter answered:
RE: Inconsistent Printing / Random Issues

@g-j-sieben

did it work ok switching filaments? i tried going back to prusament, unloaded and reloaded several times and it’s still not printing normally

Posted : 24/12/2019 5:25 am
digitalkid56
(@digitalkid56)
Active Member
Topic starter answered:
RE: Inconsistent Printing / Random Issues

UPDATE: 

- So I removed the filament sensor, issue still occurs.

- Attempting to print with 3rd party filament is definitely worse, within layer 2 or 3 of the included Benchy file, it starts to skip.

-  I switch to purple Prusament, starts printing well until it gets to a flat layer of the Benchy, then starts to skip a bit, then prints good again over the infill area. 

 

It seems to have issues pushing filament thru at higher speeds, and filament sizing definitely affects it, but it does it with consistent prusament as well. Does anyone know if theres a way to adjust the tension on the filament gearing?

Posted : 24/12/2019 8:41 am
xhillb61
(@xhillb61)
Trusted Member
RE: Inconsistent Printing / Random Issues

Did you try increasing nozzle temp?

Posted : 24/12/2019 9:14 am
xhillb61
(@xhillb61)
Trusted Member
RE: Inconsistent Printing / Random Issues

Did you try increasing nozzle temp?

Posted : 24/12/2019 9:14 am
digitalkid56
(@digitalkid56)
Active Member
Topic starter answered:
RE: Inconsistent Printing / Random Issues

@ulrike-b

I have not, but I'll try that.. It's weird because everything printed fine for about 5 solid prints. Then suddenly it started having issues.

Currently the Benchy is printing at 210. Will try different temps and see if theres a difference and report back.. thanks for the suggestion!

Posted : 24/12/2019 9:17 am
jockspice
(@jockspice)
New Member
RE: Inconsistent Printing / Random Issues

Same problems with several filament types, clicks and loses steps, leading to inconsistencies. Still troubleshooting!

...
Posted : 26/12/2019 4:08 pm
digitalkid56
(@digitalkid56)
Active Member
Topic starter answered:
RE: Inconsistent Printing / Random Issues

** UPDATE ** 

Ok so I've tried a couple of things and it's been working so far..

- Increased nozzle temp (by about 10 degrees). Normally I print PLA around 215, by increasing nozzle to 225, it's been clearing up the sputtering and clicking for the most part. Every now and again I hear something, but can't determine if its just he filament creeking in the bowden or if it's slipping in the gearing.

- Secondly, I've been reading about loose screws in the heatbreak and strain on the sensor/cables. so I've downloaded and printed these replacement parts made by Pekcitron on thingiverse to alleviate any kind of strain. https://www.thingiverse.com/search?q=prusa+mini&dwh=55e045ff7cfeb9

 

So far everything has been going ok, will update if any other issues arise. Also, let me know if these have helped any of you with the same issues!

Posted : 26/12/2019 11:19 pm
Koen Kooi
(@koen-kooi)
Eminent Member
RE: Inconsistent Printing / Random Issues
Posted by: @jockspice

Same problems with several filament types, clicks and loses steps, leading to inconsistencies. Still troubleshooting!

The extruder clicks when the motor doesn't have enough torque to force the filament through. On my MK3s this happens when printing 0.07mm or smaller solid layers, the material on the print bed gives too much back pressure and the extruder can't cope.  On another non-prusa printer the extruder motor has more torque and starts grinding down the filament.

Raising the temperature, lowering the print speed and/or lowering the flow rate helps, but I can still find models where it prusaslicer can't generate non-clicking gcode with all the changes above. 

I can't decide if having lots of retractions helps or only hides this issue.

Posted : 27/12/2019 9:51 am
jockspice
(@jockspice)
New Member
RE: Inconsistent Printing / Random Issues
Posted by: @koenkooi
Posted by: @jockspice

Same problems with several filament types, clicks and loses steps, leading to inconsistencies. Still troubleshooting!

The extruder clicks when the motor doesn't have enough torque to force the filament through. On my MK3s this happens when printing 0.07mm or smaller solid layers, the material on the print bed gives too much back pressure and the extruder can't cope.  On another non-prusa printer the extruder motor has more torque and starts grinding down the filament.

Raising the temperature, lowering the print speed and/or lowering the flow rate helps, but I can still find models where it prusaslicer can't generate non-clicking gcode with all the changes above. 

I can't decide if having lots of retractions helps or only hides this issue.

For those having problems with this, on a new build machine using Prusa profiles, the problem has to be hardware. I haven't had the chance to investigate further yet, but given the other threads, I expect to find loose grub screws and extended hot zone causing the problems. 

Never had this on any printer before, let alone the MK3S or MK2SMMU2. Guess there are more advantages to doing a full build yourself 👍

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Posted : 27/12/2019 2:02 pm
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