UMO+ extrusion problem

[kervert 3]

so, my prints start fine and print beautifully up to a certain point. no under-extruded layer, just a flawless print up to a certain point and then it stops, sometimes after about 40 minutes, sometimes after 5 hours. i just replaced the hot-end with a brand new kit, so i feel it's safe to say we can rule that out. i replaced the little gear on the material feeder with an acrylic one my laser friend cut for me and since then i haven't had any gear slippage like i used to. i replaced the nut on the tension spring, which i found to be stripped and in doing so thought i had finally found the culprit. no such luck. i have played with all kinds of different tensions, including having it maxed out. the only thing i can figure is that the knurled nut on the material feeder is worn, although it still feels gritty to me, but i don't remember what it used to be like. that or a worn out e-motor, but i don't think so. i cant find a replacement for the feeder nut anywhere. does anyone know where to find one, or if i can somehow use the um2 feeder nut, because those are easy to find. any help or suggestions would be greatly appreciated. thanks

-kurt

[kervert 3]

okay i just sharpened the knurled bolt with a dremel and made a new one with deeper cuts, neither fixed the issue and then i tried both at 220 with a 0.8mm nozzle and still the extrusion stopped after just about 10-15 minutes.

i'm completely at a loss...

[neotko 1,417]

Your hotend is leaking. Between the nozzle and the barrel.

https://ultimaker.com/en/community/22351-ultimaker-original-plus-help

https://ultimaker.com/en/community/38880-umo-hot-end-leaking-above-heater-block

Read both posts and the follow ups.

Also. IMO, you will need a new bolt, doing that changes the esteps and the distance on the feeder might create a gap that will make the filament skip.

[kervert 3]

i know that. i should have said that this all goes back way before the leak and would happen when there was no leak, which was the case up until recently when i switched to the .8mm nozzle hastily and in a bad mood. it's not the cause of the problem. i am sure. also i have switched back to the original bolt until i find a suitable replacement

[rowiac 53]

If your hot end is brand new and clear, then the problem could be with the feeder or the bowden tube. If filament slides freely though the bowden tube, then it probably isn't that.

Inspect the black plastic roller in the feeder to make sure it isn't damaged. If it is. it can cause inconsistent tension and periodic under-extrusion. If the feeder tension is set too high and still grinds sometimes, this can create burrs on the filament and loose particles that make it difficult for the filament to slide through the bowden tube, exacerbating the problem.

When I was having a similar issue, I had found that if I fed fresh filament thought the bowden it would slide easily, but filament that had already been through the feeder once (had marks from the knurled bolt on it) had significant resistance in the bowden.

[kervert 3]

replaced the feeder wheel with one i cnc milled from acrylic and it's like a brand new machine. printing. perfectly.

[amedee 349]

It is actually a common problem on the UMO.

You can also replace the molded part by a 8x14x4 bearing (See here for a picture)

Edited April 26, 2017 by Guest

[rowiac 53]

@kervert,

Wow, that roller was in bad shape.  Mine wasn't quite as bad, but it still caused problems.  The acrylic roller should last a while, but I ended up replacing mine with the ball bearing that @amedee mentioned. It was less than $3 on ebay; size 8mm ID x 14mm OD x 4mm W.

Edited April 26, 2017 by Guest

[kervert 3]

acrylic roller broke. snapped into 3 pieces. i replaced it with the bb and it seems to working just fine. thanks for the suggestion