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Help: Our printer has turned into a child!  

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sebastiana
(@sebastiana)
New Member
Help: Our printer has turned into a child!

Hi,

 

We have a coupleof Prusa printers in our office, and one of them started acting up and in the end is impossible to print with. It seems like there is either a combination, or cause/effect of not enough plastic coming out of the extruder that the plastic does nto stick well to the bed.

I have tried running a first layer configuration and I would describe it as such:

  • It is able to lay the first "test line" down in the bottom left corner with a nice fat plastic string
  • It starts on the zig-zag well, but the extrusion is suspicously thin (?)
  • When it gets to the "mesh" at the end it really shows that something is up: the plastic "slips" as it is put down on the table, the plastic has variance in thickness, and is overall very thin. When you print "actual" prints the best way to descripe is that the first layer looks like its been done by a 3-year-old.

We have tried:

  • Changing the sensor in the bed (which was faulty + cable)
  • Several cold pulls, and needle runs
  • High temperature extrusion (to try to clean out nozzle)
  • Firmware updates
  • Calibration and Z heigth adjustments.

The only thing that we have not done is take apart the extruder. Any tips or experiences? See pictures below.

This topic was modified 5 years ago by sebastiana
Posted : 14/05/2019 6:39 am
sebastiana
(@sebastiana)
New Member
Topic starter answered:
RE: Help: Our printer has turned into a child!

Another Image.

Posted : 14/05/2019 6:48 am
Vojtěch
(@vojtech)
Honorable Member
RE: Help: Our printer has turned into a child!

You say you tried Z height adjustments, I assume you mean 'Live Z'. However, 'Live Z' is the one parameter that is clearly not correct in your images, you need to go quite a bit more negative and squish the filament more. It doesn't seem like an underextrusion at the first glance, so I wouldn't suspect a clogged nozzle immediately.

What you call the 'test' line is a purge line, where the printer is making sure there are no bubbles or anything else in the nozzle, it's usually several times thicker than normal extrusion. Normal extrusion should be 0.45mm wide and 0.20mm tall.

This post was modified 5 years ago by Vojtěch
Posted : 14/05/2019 10:37 am
bobstro
(@bobstro)
Illustrious Member
RE: Help: Our printer has turned into a child!
Posted by: sebastiana

[...] I have tried running a first layer configuration and I would describe it as such:

  • It is able to lay the first "test line" down in the bottom left corner with a nice fat plastic string
  • It starts on the zig-zag well, but the extrusion is suspicously thin (?)
  • When it gets to the "mesh" at the end it really shows that something is up: the plastic "slips" as it is put down on the table, the plastic has variance in thickness, and is overall very thin. When you print "actual" prints the best way to descripe is that the first layer looks like its been done by a 3-year-old.

I've got some pics on what the Live-Z routine should look like that might help give you a reference for comparison.

  • Be sure your PEI print surface is clean. If not, the filament can lift off the PEI surface making it look like your Live-Z adjustment is off. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. Take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails, and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent to give it a very light buff, but only infrequently.
  • If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine. 

And above all else, avoid touching the PEI print surface.

This is what the little rectangle should look like at the end of the on-board Live-Z print:

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 14/05/2019 2:36 pm
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