SOLVED A weird problem with under extrusion. All suggestions welcome.

[jonatanrullman 17]

Hi everyone,

I'm having the weirdest problem with under extrusion on my Ultimaker 2 lately. I'm out of ideas for what it could be.

It is a regular 2 but upgraded with olsson block a meduza gearbox and iroberti feeder and a new drive wheel. I have used this setup for hundreds of print hours without trouble. I'm also using laberns spring replacement.

Things I have done so far.

*Checked the teflon. I'm using I2K and it looked like new. I'm wondering if there could be a little too much pressure from the spring replacement as I replaced that one recently.

*Monitored the temperature during print. Doesn't overshoot or fall below the set temperature by more than a few degrees.

*Checked the extruder steps using the move command. For 100mm of movement the filament moved about 100+-1mm inside the bowden tube (I had retracted it quite a bit so that resistance in the nozzle wouldn't cause trouble).

*Checked the settings in the printers PLA profile. Flow is 100% and filament diameter is 2.85mm.

*Checked the printer profile in Cura for filament diameter which was also set to 2.85mm.

*Measured the filament, my cheap digital calipers say 2.77 which seem close enough to 2.85.

*Upgraded the printer firmware from Tinkergnome 16.08.2 to 17.10.1.

I printed the volumetric test. As can be seen the printer does not have much trouble with 10mm3/s. Though the text suffers quite a bit and on the 10-speed you can see a little bit of under extrusion or similar trouble just after the text. Looks good otherwise though.

This is the actual problem I have. It is sliced with Cura 3.0.4 and the default fine profile with the only change being skirt instead of brim. I aborted the print on the third layer. Notice especially the inner perimeter on the left side. The small holes in tight corners I read somewhere might be a bug that has been fixed in Cura 3.1 so that doesn't concern me all that much right now.

Has anyone got any suggestions at all? At this point I'd try sacrificing a rooster while naked in the dead of night if I thought it would help.

Cheers

Edited November 2, 2017 by Guest

[UbuntuBirdy 56]

I had the same problem a cuple of weeks ago. What is the value of infill overlap in cura? I had to rise this value, only a 1 or 2 % and the problem was gone.

[jonatanrullman 17]

I had the same problem a cuple of weeks ago. What is the value of infill overlap in cura? I had to rise this value, only a 1 or 2 % and the problem was gone.

It is currently at 10%

I have tried adjusting that as well. I will give it another go so be sure.

Note though that the problem does not appear to be with the infill. The innermost and outermost perimeter of the three looks just fine, it's the one in the middle that is printed at a faster speed that shows under extrusion.

Though it is possible that the innermost perimeter is part of the infill and as such should overlap the one in the middle.

This is a more close up photo. There also seems to be quite a wide gap between the lines even on the second layer. Almost like the first layer when the nozzle is slightly to high.

[UbuntuBirdy 56]

hmmm ... first sign of a clogged nozzle? What is the extruder temp? Did you try to rise this themp for 5 or 10 deg?

[jonatanrullman 17]

hmmm ... first sign of a clogged nozzle? What is the extruder temp? Did you try to rise this themp for 5 or 10 deg?

Could be. Would be worth making a thorough cleaning of it. I do an atomic pull pretty much every time I switch nozzle.

I have a brand new 0.4mm nozzle I could try as well and see what happens.

Extruder temp is 210C. Shouldn't need to be any hotter than that but it would be interesting to see what happens at 200 and 215.

I will try these things tonight or tomorrow. After doing the prints above I packed up the printer because I'm doing a presentation about 3D printers to new members of our maker community and I couldn't do it without my Ultimaker now, could I? :-)

Cheeers

[stu_le_brew 42]

Just a thought - is the filament at or near to the end of the reel, I have once had a problem with some filament causing extra friction in the bowden tube as it seems to remember being tightly curled on the reel.

Not had this problem since I upgraded to the BondTech feeder which is very much more powerful

[jonatanrullman 17]

Just a thought - is the filament at or near to the end of the reel, I have once had a problem with some filament causing extra friction in the bowden tube as it seems to remember being tightly curled on the reel.

Not had this problem since I upgraded to the BondTech feeder which is very much more powerful

 

Unfortunately no. This is a 5kg spool and it has plenty left. The volumetric test worked well all the way. I'm thinking that it is a much more delicate problem at work.

Cheers

[UbuntuBirdy 56]

no one could do it without his Ultimaker!

[jonatanrullman 17]

Alright. I think I have sorted this out (pending more tests).

200 and 215 degrees, new nozzle and a complete reset of cura. No change what so ever.

Then I did a factory reset of the printer. Mostly as a desperate measure. It has not been done in many a month as I can recall. The configuration has been through quite a few changes back and forth as well as an upgrade to the latest version (though that was after the problem arose).

The only major change of settings I know that I have done is to lower the fan max because it cools the hot end too much. I have it capped on 65%. After the reset that was back to 100% which works for a few layers before the printer thinks the PT100 has failed. The first layer looks like crap because I couldn't be bothered calibrating the build platform properly. But that doesn't really matter right now.

I obviously had to recalibrate the feeder steps because I forgot to write down the number. But since that was within 1% and it is now within 1% I assume that can't be the cause of this.

Below is a print right before the reset and right after with 65% fan (the 100% fan looks the same). Both aborted at about the same time. I think one is the third layer and one is second or fourth. But no matter really as every layer was as bad before. The factory reset is literally the only change between these two prints.

As you can see it is night an day. I really have no idea what in the printer config that might have caused this problem. It is very strange.

Thanks for all the suggestions.

Cheers

Edited November 2, 2017 by Guest