UM2 under extrusion/Bowden tube problem

[leoddc 74]

Hi. I've been experiencing some under extrusion problems lately and I think it might be down to the bowden tube. I have noticed that the bowden tube moves up and down a few mm where it connects to the printer head especially when a retraction occurs. I have tried reattaching the clip but it doesn't seem to help fasten the tube. In the image below you can see the under extrusion problem. If you look at the print on the right you can see where I have manually held the bowden tube in place and produced better results (the smoother area).

I think if I can get the tube to stay put it will fix the problem but I just cant seem to get the clip to keep it in place.

Any help would be much appreciated.

 

[illuminarti 18]

See my instructions for inserting the tube in the clip, here:

http://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/?p=40399

You might also try cutting off just a few mm of the end of the Bowden tube, so that the plastic collet has fresh plastic to grip into.

 

[gr5 2,172]

Assuming UM2.

I've seated my bowden nicely such that it doesn't move but I wouldn't expect it to help your pictures - it helps retraction quite a bit - I now get by with a bit less retraction (4.5mm now, 5.5mm when bowden was moving on my UM2 same thing with my UM Original - bowden more secure and now 4.5mm is enough).

Instead I think you should check your Z levelling again - you need it slightly closer to the bed such that the first layer is squished just a bit more. I wouldn't touch the 3 screws - just do the levelling with the controller.

 

[leoddc 74]

Thanks for the replys. Illuminarti I've just been reading that thread, very helpful. I'm sure that the movement in the tube is whats causing my problem.

So let me check that I got this right... I need to remove the little blue clip, loosen the four big screws at the top of the printer head, push the bowden tube down into the white tefflon fitting while lifting the white ring (the one that the clip sits under) tighten the four big screws back up while still keeping the tube pushed down and then replace the blue clip with this one I downloaded from youmagine.https://www.youmagine.com/designs/ultimaker-extruder-mutli-clip

dose that sound about right?

I'm about half way through an 11 hour shift at the moment and I cant wait to get home and try to fix this

 

[gr5 2,172]

I found that if you do all those steps you won't need any clip at all as the pressure on the bowden will hold it in place.

 

[gr5 2,172]

But again - I think your problem is leveling.

 

[leoddc 74]

Thanks for the info gr5. I re-leveled the bed a couple of times earlyer today just in case. The prints start off ok but as soon as there is a retraction the tube moves quite a bit and thats when the problem starts. I've also noticed that I have those bulging/mushroom shapes at the end of the filament when I do a filament change. When I get home tonight I'll try a print with retraction turned off and see how it looks and then I'll go about fastening the tube. I'll check back here tomorrow with an update.

 

[leoddc 74]

Awesome!! It totally worked. I didn't even need to loosen the screws on the printer head, I just pushed the tube down, pulled up the white ring and fitted a thicker bowden clip. No movement at all now. I also leveled the build plate for good measure. Printing great so far. Fingers crossed it stays that way