Print ruined after a few layers

After taking the printhead appart to adjust the length of the PTFE tube, the printer no longer performs well.

After a few layers, the print almost seems to be overflowing. See the attached images.

With a good print in the background


Also when the print was done, it was hotter than normal and could easily be bent.
Could the heat sensor be damaged?

The calibration piece:

[quote=“tsjostedt”]After taking the printhead appart to adjust the length of the PTFE tube, the printer no longer performs well.

Also when the print was done, it was hotter than normal and could easily be bent.
Could the heat sensor be damaged?


Did you check that the temperature sensor “bead” is still in the middle of the hole in the heater block?


I’ve now left the heater block overnight in acetone to remove any plastic debris.

I will try to reposition the sensor to make sure that it is exactly in the middle.

No that did not work either.

Still ruined after a few layers.

Posting some more pictures of the top and bottom of the test pieces.

Consistently bad

Bottom side, note that the layers are relatively tidy.

Bottom side

Last piece printed was also hot and easily warped when finished, something that never happened before.

Measured the resistance of the thermistor in room temperature (25 degrees) and it was 80 kohm. The printer says its 30 degrees when turning it on.
I’ve tried twisting and realigning the thermistor with the same result.

Obviously, you’re overheating your filament. Stock values are too high but yours look sky high. Try lowering the temperature to 190° (PLA) and the flow to 70%.

The temperature for this print was set to 195 degrees and 73% flow. The actual temperature is probably a lot higher.

Its just to small? Try to print 2 at the same time, or scale it. Because to me it looks like the print is just to small to cool down each layer?

Tried printing the Vertex log key chain (which I have printed many times before without any problems) with the same result.

Are both fans on the printhead spinning when you are printing?

I think the axis cooling fan is running but not the small extruder fan. It is running when preheating the PLA though.

I don’t remember seeing the small fan running that much on earlier successful prints either?

Should be spinning 100% of the time IMHO
It could be you lowered the percentage it runs on to low so it doesn’t run at all. (set @ 50% I think it doesn’t move at all)

Got a replacement temperature sensor, mounted it with the thermistor bead exactly in the middle of the heater block.

Started printing the Vertex logo, even made sure the fan was running 100% straight away. Have printed this one many times before without any problems.

Did U try a new nozzle? Could be U made the nozzle hole to big by cleaning it. And now its not continuously extruding any-more or something like that? Like oozing all the time. Could U make some pictures of the Nozzle? Maybe someone can spot something that’s off by that?

Kind regards

Yes, I tried changing the nozzle as well since I had a spare one.

Doesn’t anyone have any suggestions on anything else to try?

I feel that I have reached a dead end here. Velleman support refuses to help out since it is not a specific parts failure.

Well maybe, try some different filament? Some other colour? Next thing that comes to mind… Did you connect the small fan correctly? Like it should be blowing towards the nozzle not blowing upwards.
You said it started with swapping in a new PTFE tube…
Well try that again maybe? Start from the things u know have changed. Also check the feeder? Is the toothed feeder pulley maybe a little lose?

You are in front of the machine, its not that easy to give more advice than already given.

But like Raby mentioned before

Bottomline is: The print becomes to [u]hot[/u] at some point. That’s the only thing that’s definite.

I only saw something happening similar when printing a cylindrical tube upright (size of a pen) and the layers hadn’t had the time to cool down and started to show the same kind of dripping as in yours. By adding a forced air-stream right underneath the nozzle I managed it to continuously spiral print that.

Does the overheating theory apply to the Vertex logo as well? To me, that one is slightly different, it almost looks like the nozzle is digging in to the top layer and cutting groves. But there are also the small “blobs” on the side of the Vertex logo, which could be an indication of overheating?

To get to the root cause why this is happening I think its important to investigate a number of theories.

Manually setting the printer to say 10 degrees lower than the melting point of the PLA. If the temperature regulation is correct it should not be possible to manually push through filament.

Printing a single wall, large diameter cylinder would also revile how the print is progressing temperature wise.

Z axis jammed or underpowered
The grooves cut into the Vertex logo got me thinking that perhaps the Z axis is not running as smooth as it should.
This should preferably be tested using a micrometer clock gauge, moving the z axis in 0.1 mm increments.

Firmware settings
When I did my successful prints I had not modified the settings of the printer what so ever.
A factory reset or and / or reinstalling latest firmware is easy to do.

Things I have already tried

  • Changing the temperature sensor thermistor
  • Repositioning the temperature sensor thermistor
  • Changing the print nozzle
  • Cleaning the heater block in acetone overnight to remove any PLA debris
  • Printing models with exactly the same gcode that has worked before
  • Setting the fan speed to 100% for the entire print
  • Aqua and white PLA (Velleman brand)

U have checked polarity of the fans?
Measure the crappy vertex logo thickness and see if that is somewhat what it should be.
Otherwise like u mentioned the Z stage is not running smooth like it should be… Could be your printing on the same level multiple times.
Try to manually go up and down and see if every 0.1mm step it actually drops/raises. If it is jumpy that could be the cause to.

Kind Regards