UM2 terrible extruder performance. Ticking at 2mm^3/s @ 230C with PLA

[rhino_aus 2]

I have had a UM2 for the longest time and have done everything I possible can to get it to print a print without failing.

I have replaced the hot end with an Olsson block, high temp PTFE coupler, 35W heater, new temp sensor, new fan shroud, |Robert| extruder, new extruder knurled gear, recalibrated the E steps, calipered my filament to 0.01, and even tried wrapping the nozzle in Kapton tape and Atomic cleaned the nozzle more times than I can count and yet *still* the printer fails with this setup:

35mm/s, 0.15mm layer height, 0.4mm nozzle, 230C, PLA.

The extruder motor just keeps skipping back and the print fails miserably.

What steps do I try before I throw this $5000 waste of money off a bridge

Edited April 5, 2017 by Guest

[stu_le_brew 42]

have you tried adjusting the tension on the extruder, looking at the list of things above I am sure you have

[neotko 1,417]

Just one question...

Try this please

a) Do an atomic pull

b) Remove the nozzle (for this is a good idea to heat to 150C at least)

c) Wait the hotend cool down to at least 35C

d) Get a piece of filament and insert it from bellow (from the opening left by the nozzle). Does the filament pass ok? Does it has some point of friction? Ofc try to straighten the filament peace so the curvature doesn't add friction.

If so, maybe when you installed the coupler the tip, due pressure, deformed.

Other question. You installed a 'high temp PTFE'. I suppose you bough a TF2K from 3dsolex that is a TFM coupler + I2K, right?

If so, is very important (IMO) to use a fixed size spacer to replace the spring of the um2. If you already did that, nevermind, but if you didn't, download and print a fixed size spacer. There are various models for I2K and non I2K users.

https://www.youmagine.com/designs/um2-spring-replacement-for-i2k'>https://www.youmagine.com/designs/um2-spring-replacement-for-i2k'>https://www.youmagine.com/designs/um2-spring-replacement-for-i2k'>https://www.youmagine.com/designs/um2-spring-replacement-for-i2k

https://www.youmagine.com/designs/ultimaker-2-spring-replacement

https://www.youmagine.com/designs/um2-spring-replacement

https://www.youmagine.com/designs/um2-adjustable-spring-replacement

[rhino_aus 2]

have you tried adjusting the tension on the extruder, looking at the list of things above I am sure you have

 

I have tried. It is quite high right now, any less and the filament will slip.

 

If so, maybe when you installed the coupler the tip, due pressure, deformed.

I suppose you bough a TF2K from 3dsolex that is a TFM coupler + I2K, right?

very important (IMO) to use a fixed size spacer to replace the spring of the um2

 

I will check this but when I took the head apart yesterday it seemed completely normal.

Yes. That replacement part but I didn't instal the I2K as I only intended to print PLA and it was not recommended for sub 240C printing AFAIK. I have it, but I haven't put it in.

I will try this but I can't imagine what it would change.

[neotko 1,417]

Yes. That replacement part but I didn't instal the I2K as I only intended to print PLA and it was not recommended for sub 240C printing AFAIK. I have it, but I haven't put it in.

I will try this but I can't imagine what it would change.

 

The only problem is that if the Coupler is TFM (milky semi transparent color) it can get damaged if you use the spring, that's something 3DSolex should explain. TFM is quite easy to compress under pressure, that's why um2+ uses a fixed size spacer for the TFM but old UM2 PTFE coupler used a spring (more resistant to pressure).

Let me show you a photo of a used coupler, that I fixed drilling, and while it was almost ok to use it did add some pressure to my prints. Compare Right (new unused) to Left (I did install it with too much pressure and fixed it with a drill bit 6 months ago until it was too much pressure for flexibles this weekend). As you can see, due my bad, it can compress a full 1mm. So the spring will damage the TFM coupler overtime making the hole smaller and smaller, adding pressure to the filament.