Serious underextrusion problem

[supersurfer 0]

Hi,

I hope someone can help me here.

I have some serious underextrusion problems. I am basically unable to print anything, the layers/ lines are to thin and do not stick to each other. Slower printing makes the problem less but still underextrusion is visible.

I use an UMO + with heated bed.

I have changed my complete hotend for a new one ( incl. Peek and ptfe piece) so clogging is not a cause. This did not help.

The extruder seems to work fine, there is no grinding.

I reflashed the marlin software to solve any sorftware issues that mught cause the problems, no effect.

I try printing gcode models that I have printed before with succes. They all come out with the same problems.

I use white PLA from ultimaker.

I would like to post some pictures but I see no method in the web interface for this.

Hope anybody can help.

Regards,

[gr5 2,167]

To post a picture click "gallery" in the top left of this page, then big "upload" button. Then edit or post and click "my media" next to smile icon.

 

[gr5 2,167]

I try printing gcode models that I have printed before with succes. They all come out with the same problems.

 

So it must be hardware.

It can be:

1) nozzle is not the temperature you think it is

2) head has partial clog somewhere

3) filament is too big for bowden and gets stuck

4) feeder not working as well as it used to

Did you say you replaced the actual nozzle and you had the same problem before *and* after changing nozzle? That might eliminate #2.

To test #4 - what happens if you push the filament by hand (open the feeder). Set nozzle temp to about 220C and push hard on the filament - does it come out okay? You need about 3KG force.

Look at the teeth marks on the filament. Are they sharp like the photo here or different than this?

 

[supersurfer 0]

Hi gr5,

Thank you for your reply.

I exchanged the complete hotend and it still displays the same problems as before so it's not 2.

The temp reading shows ambient temp when I switch on, so I guess it is not 1. Also: the pla flows well when pushing through by hand.

I have tried different filaments that used to work well so I guess it's also not 3. When I insert the filament it's pushed in easy and I do not notice any more friction than before.

Than maybe 4? I get an even teeth mark on the filament. It does not display grinding. I will try to post pictures.

Regards,

 

[supersurfer 0]

I discovered using an Ipad does not display all functions of the post editor, better to use a laptop......

so here are some pictures:

 

Here you can see the thread does not fuse with the others next to it.

 

the bottom piece is something I made earlier and is like a completely loose bunch of thread.

 

the extruder dents the filament, I see some repetitive pattern, this is possibly retraction?

 

[chrisr 18]

Are all the pulley grub screws present and tight in your machine?

 

[supersurfer 0]

Are all the pulley grub screws present and tight in your machine?

 

Good point! I found one screw loose, it was on the non driven shaft in the front though.

I did a test print and it does not look better.

 

[luke-dann 0]

I'm getting the same problem and it seems to be my filament isn't getting drawn into the machine. The filament just isn't getting gripped by the extruder and I have to keep refeeding by hand every minute or so. Trying a few things to correct it. Will post some images of the results when the print is finished.

 

[supersurfer 0]

Hi Luke,

If I hold the filament under the extruder I can feel it being pulled in nicely.

Maybe the settings in the machine are off by some strange reason ( I have kids who also use the printer).

Reading the settings on the ulticontroller:

under control/temperature/

PID-P: +022.20

PID-I: +001.08

PID-D: + 114.00

PID-C: 1

under control/motion/

Accel: 4000

Vxy-jerk: 20

Vz-jerk: +000.40

Ve-jerk: 5

Vmax X: 500

Vmax Y: 500

Vmax Z: 30

Vmax E: 25

Vmin: 0

VTrav min: 0

Amax X: 9000

Amax Y: 9000

Amax Z: 100

Amax E: 10000

A-retract: 3000

Xsteps/mm: +078.74

Ysteps/mm: +078.74

Zsteps/mm: +0200.0

Esteps/mm: +836.0

I do not know what it all means. Is there an explanation of this somewhere on this forum?

Can anybody see a wrong setting?

Regards,

 

[chrisr 18]

Good point! I found one screw loose, it was on the non driven shaft in the front though.

I did a test print and it does not look better.

 

Is the feeder grub screw tight too? :-)

 

[gr5 2,167]

Your underextrusion appears to be almost exactly 50%. This is very suspicious.

I'm thinking either the E axis (extruder) is moving exactly half as much as it is supposed to or the Z axis is moving 2X. You should test both axes. Also you replaced the Z axis recently. Maybe Ultimaker shipped the wrong Z stepper to you. The steps/mm in your posting are correct (836 and 200 for E and Z).

Are parts twice as high as in CAD? Measure them accurately.

Or alternatively control your printer directly through USB and command the Z axis to move 10mm and see if it really does. Then command the extruder to extrude 10mm (it won't move unless the nozzle is >170C). Mark the filament and see if it really moves the commanded distance.

Also maybe you bumped the E axis jumper and it is moving at 1/2X normal. Check all the jumpers in this photo - only the circled jumper should be missing or out - especially check E axis:

 

[supersurfer 0]

Hi,

The picture of the board is from an UMO I presume, I have the UMO+ which has the UM2 white pcb. See picture; no jumpers present.

I have no new Z axes or stepper, so no change there.

Tested Z axes: 10mm stepped with ulticontroller measures 10mm.

Tested E axes, extruded 100mm of filament (through the ulticontroller). This is the outcome:

thread of 0,5mm thick, Length=2615mm. If I calculate it correctly this amounts for 513mm3 of PLA.

I also marked the PLA and moved 10mm with the extruder, this is exactly 10mm.

The printed parts have exactly the same size as before.

There is no grub screw on the extruder gear wheel, it has a flat surface so it is not able to move on the shaft.

It seems to be a complex problem :sad:

 

[supersurfer 0]

I have changed the standard clamps for a moon cactus design: http://www.thingiverse.com/thing:45236

At first I did not think this will be of any influence in the under extrusion problems but I am wondering if this might not be the problem.

 

[supersurfer 0]

I have found the cause!

I have discovered that the press wheel in the extruder is deformed due to the high pressure on the filament. This has led to the wheel getting stuck thus giving higher than expected friction in the extruder.

It seems the wheel material is not strong enough.

Thank you guys for your support!

Regards,