Totally busted extrusion on Ultimaker Original +

[brentwerder 13]

My Ultimaker won't extrude anything during prints unless I help it through the extruder with pliers. I tried to troubleshoot a bit myself by testing for any obstructions in the bowden tube, but there were none until the filament hit the hotend. It felt like it had just stopped, then it began extruding when I pushed on the filament really hard. This is all with the hotend at 210C, as I always print. I did multiple atomic pulls to make sure it wasn't clogging, and I tested the filament running through the hotend with the tube out. I still don't know what is obstructing the filament. It isn't the PTFE coupler - I made sure of that. The printer prints a decent first layer (actually a phenomenal first layer because I leveled the bed maybe 5 times in an attempt to fix the issue), then begins underextruding or clogging. Someone help!

[neotko 1,417]

Check:

The bowden inside the hotend. It might be twisted.

The ptfe coupler. Take it out and spin it on a filament peace. If woobles it's wore out. If passes hard on the filament, also wore out.

Make a photo of the hotend, bellow the peek look for black goo. On the alu block, look for black goo. If so, you have a leak.

Check the feeder assembly. It's all really ok? Photo.

[brentwerder 13]

No goo anywhere, so thats good (I had to replace my old brass tube for that reason exactly). I tried taking the PTFE couplet out and it seems to move fine around the filament with a small gap. I tried swapping it with my backup and started a test print maybe 20 minutes ago - still working OK. I dont have high hopes that itll finish, though. Another update coming later. Thank you for the suggestions neotko!

[brentwerder 13]

Fail.  I kind of expected that, but I dont know where to look next.  I can post a pic of the feeder later, but I find it hard to believe that its the culprit.  I feel quite a bit of resistance when pushing filament to the nozzle.

[neotko 1,417]

Umm. Please post a photo of a pair of atomic pulls. Also, clean with a brush the knurted bolt of the feeder. Also try printing the same 10C higher. Let's try to debug your problem bit by bit.

[gr5 2,192]

It may be a nozzle clog - or at least a very thin layer of carbonized gunk inside the nozzle tip. Consider getting a few extras - they are very inexpensive. Also consider removing the filament and nozzle while hot, letting it cool, then stick filament up from below to check for problems. I suspect everything is fine in there other than nozzle and possibly feeder.

You could check the pull strength of the feeder. UMO and UM2 are both about 10 pounds pulling strength.

[brentwerder 13]

Well. I made this post a few hours ago and apparently it didn't post. Well, I'll try again.

I tried everything both gr5 and neotko suggested with no success. I'll try to elaborate:

Cleaned the knurled bolt and tested the feeder by hand with the bowden tube out of the hotend, seemed to work just as well as always. I put a bit of pressure on the filament coming out to ensure that it was working fine: definitely (probably) not the culprit.

Cleared out the nozzle with a few atomic pulls:

Worked very well - pushing filament through the hotend by hand worked very well. Nice, thick, even extrusion by hand. However, attaching the bowden to it and trying to feed with the feeder didn't work at all. I was able to get a bit of extrusion and tried the 40mm cube test that I usually use (10C higher than usual @225C, as per neotko's request) and not surprisingly it failed horribly.

gr5 - I swapped the standard Ultimaker nozzle with my spare, and it didn't work. Tried one of my 5 Chinese nozzles (that has surprisingly printed very well in the past) and it failed too. I tried the test you recommended and found no obstructions.

How do I test the pull strength? I'm judging the strength off of the assembly guide which stated that the tensioner spring should be about 10mm long, and in the past that has given the right amount of compression.

Thank you both for your help - and hopefully I can get up and running soon!

[neotko 1,417]

It must be just the photo focus but the coupler doesn't look 'round'.

Did you try to take the bowden out and check it feeding filament trough? it should move without tension at any point. If so it might be dmg or twisted as some point.

One more crazy idea. It's your coupler good or china? China can work but there's a think about the upper length that some china shops sells just wrong.

Juat in case. Check this:

Edited May 31, 2016 by Guest

[gr5 2,192]

Make sure you push the filament from the feeder end by hand with the feeder "open". First pull it out half way and the push it back in so you can feel the resistance in the bowden as rarely that is the problem. Then feel is it hits each "bump" e.g. teflon part, peek part, nozzle. Doing this and then seeing how fast it flows with a given amount of push is good practice so that you get a feel for "normal" (it's a bit too late for that perhaps).

If you really want to test your feeder strength here is how I did it:

[gr5 2,192]

Note at least 15 pounds of weight in the pot. Note the scale. I hit the "tare" or "reset" button on the scale when there is no tension on the feeder, then I feed using pronterface (that's pronterface running on the laptop). I tell pronterface to feed slowly - maybe 1mm per second - (60mm per minute) and then tell it to move extruder 100mm and watch the scale memorizing the max value seen and write it down. The feeder on the UM2 has more power at higher speeds but the feeder on the UMO doesn't as it is limited just by the knurled wheel's ability to grip (and tension and the bearing wheel, etc).

I did this test for UM2 and UMO and they are similar both around 10-15 pounds or 5kg.

[gr5 2,192]

More details here from this 2 year old post:

https://ultimaker.com/en/community/5222-pulling-force-of-um-extruder

[brentwerder 13]

Seems like a very interesting test, and it seems like it needs quite a bit of setup! I think I'll leave that test until later because, as I've mentioned, I don't exactly think thats the issue.

Neotko - interesting idea! The 2 PTFE couplers I own are both from Ultimaker, and they both are still round. I've seen a coupler thats warped like you're saying. I'll make sure the length is correct anyways!

[gr5 2,192]

Your feeder is a bit chewed up. Sometimes that wood dust gets onto the bowden and carried into the nozzle and causes a clog. Even though the nozzle looks clear you might want to just unscrew it (make sure it's heated to at least 150C when removing as plastic can act as thread lock) and then scrape it clean from the inside.

Although of course a cold pull does pretty much the same thing if one thing doesn't work try another.

[gr5 2,192]

Oh wait - you already swapped nozzles. Never mind.

[neotko 1,417]

Crazy ideas of weird errors Inhad with the wooden feeder until I took it out forever.

- Black plastic that has a small bearing (the one pushing the filament). Inspect it and see if isn't damaged and spins. If you fell friction the screws might be too tight.

- If you push the feeder whell do you hear any woodvswood sound? That can be fixed by softening the assembly so the wood doesn't hit wood.

- The part that clamps the feeder, if it's installed inverted it doesn't clamp the feeder. Make a side photo of your feeder.

- Do the bearings inside the wood panels of the feeder move freely? This happened to me on a umo frame that had a laser cut error and the panels where tilt. Also the bearings can go wrong (it shouldn't happen but worth to check).

- It's the bowden really secure when all its assembled? Does it slip or move when retracts occur?

[brentwerder 13]

I checked all of the above - it seems like its all in working order.  No friction on the feeder, and the bowden is held firmly in place.  Here's the picture you wanted:

I tried tightening the bolt that held the bearing, and that seemed to help the push strength.  Hopefully that will help in another test.

[neotko 1,417]

You know that the upper lever, the black one near the bowden should be down?

Just asking because maybe you did the photo with the feeder ready to print. Sorry just trying to cover all bases.

Like on this photo.

Also, don't overtight it, the plastic can break leaving room for the screw to go futher in and scratch the plastic bearing. I know because I broke one once while trying to make that feeder work with 1.75mm filament.

[neotko 1,417]

Like this. Woa took me a good 2 mins to actually find a proper photo.

It's from this video 1:30ish

 

[brentwerder 13]

Don't worry - I know how the feeder should be when it's ready to print! Otherwise I'd have quite a bit of trouble getting it to work at all

[brentwerder 13]

Alright. I dont know what to make of this next print, but I think it's better than nothing!!

The entire print is underextruded, but the good thing is it's constant underextrusion - which means it was feeding (at least kind of) the whole way through! I'll tweak a few more settings, since I was printing with a high-temp filament. Hopefully this means the next print will work great!

[brentwerder 13]

Okay, I lied. Tried another cube with a lower temperature material. Failed within a minute of starting it. what's going on?!

[brentwerder 13]

I think I found a culprit. It's kinda funny how small it is, but I think it might be the problem!

Boop! Completely stripped nut in the tensioner part of the feeder.

This is the nut that held in the spring. I can't upload the photo I found in the assembly guide for some reason, but hopefully you understand which one I'm talking about.

I'll try replacing it and I'll update later!!

[rowiac 53]

@brentwerder:

I know this is an old thread, but I'm experiencing a similar extrusion problem with my UMO+ and I'm wondering if you were able to fix it.

In my case the feeder roller (the black plastic part with the small ball bearing in it) has a groove worn in one side of it. This seems to be causing uneven feeder tension as it rolls resulting in under-extrusion at regular intervals. I'll need to verify this theory by replacing the roller.

[gr5 2,192]

So it's very easy and inexpensive (a few dollars) to buy ball bearings of many sizes. The black ring is made out of a plastic called "Delrin". That delrin ring is better off replaced by a second ball bearing.

They come in integral sizes of mm. So measure the existing bearing outer diameter and the delrin outer diameter and buy a steel bearing with those two diameters. Very cheap, arrives fast in the mail, will outlast any silly plastic delrin part.

[gr5 2,192]

examples of cheap bearings:

http://www.ebay.com/itm/like/122378224272?lpid=82&chn=ps&ul_noapp=true