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Andy Gough

UM3 ABS grinding/jamming

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I have had an Ultimaker 3 for about a month now and so far am really enjoying using it. It's my first 3D printer so I am a novice in the 3D printing world. All my prints in PLA for the the most part have worked great, but in the past week I've been having real issues with ABS prints. I'm printing an Antweight fighting robot so need the need the impact resistance of ABS. When I got the printer initially the same model printed perfectly first time, but now a few weeks on I am having consistent failures where filament stops extruding between layers 3 and 8, at this stage of the print its pretty much a flat plate of around 10cm x 10cm (nothing fancy). I can't tell if it is the nozzle getting clogged that causes the feeder to grind down the filament or the feeder just manages to do that itself, but essentially the feeder grinds down the ABS and it stops extruding and the print fails.


I'm using new original Ultimaker ABS filament which is open less than 4 weeks and has been stored in a zip lock bag between prints. I've tried two different rolls, black and white. I'm using Cura with Recommended settings with a layer height of 0.15mm, most prints have been at 235dgC but in case it helped I up the temp to 245dgC for the one print (same result). The feeders tension setting is right in the middle. I've tried with both extruder 1 and extruder 2, same result (therefore different feeders and print cores).


I'm really at a loss as to what else to try. The only thing I can think of is I haven't manually levelled the print bed and am using the active levelling instead, but as I said PLA prints are coming out perfect.  Cura settings from last attempt attached.


Any suggestions welcomed.

Screenshot of Ultimaker Cura (26-02-2018, 09-46-51).png

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Hi and welcome!


Is it failing when it start printing the infill or is it failing on bottom layers?


You might want to check the infill speed (you can display this by clicking on the gear next to the speed settings. I would put it to 50 or 40mm/s, or you can simply reduce your global printing speed (i personnaly like more to change all the speeds)

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I usually print at 40mm/s


I'm guessing your print with the .4mm core right?


If you have been grinding filament for some reason it's mostly sure that the feeder is quite dirty inside, maybe it should be cleaned. If you are sure the nozzle is not clogged then it could be that.


You can check out this link to open the feeder:




You don't need to completely take it off, just be able to clean the knurled wheel

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Abs is a difficult material and impact strength is better than ancient formulations of pla but about the same as modern pla.  If you need it to be really tough then maybe nylon is better.


Also pva doesn't work with abs I believe.


245c should be fine and set fan speed to 1 to 3% on um3.  Build plate to 105 or 110.  Cover feont of printer and preferably top also.  Not sure what your issue is however.


Probably you are.printing too fast.  What are all your speeds? (Inner outer shell infill and support).  What are all your line widths?  Which nozzle and what is layer height? Oh I see layer is 

15.  Make sure cura isn't printing with a line width wider than nozzle width.  That's easy to do by accident and causes grinding.


Hopefully it's just the fan too high.

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1. If your filament is grinding, you may also have grindings in your bowden tube enhancing friction.


2. New spool? Old spool? Wonder if the filament is a bit stiffer than new and does not relax enough in the tube.


3. Did you thoroughly clean the nozzle between filaments? Hot and cold Pulls? Mixing filament types in the nozzle is not good.


4. How tight is the coil on the filament? For instance, sometimes as the filament gets towards the end of a spool, it will be very tightly coiled. If spool has been wound for too long, it can remain very stiff and bind very much in the bowden tube. This can be affected by time on warehouse shelf and not in use at your place of operations.

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Thanks @DidierKlein yes using the standard 0.4 AA print core that came with the printer. I'll try 40mm/s and see how I get on. I'll also try cleaning out the feeders, but as I said I've tried both extruders and I'd never had an issue with grinding before on either of them.


Thanks @gr5 as @DidierKlein said fan speed is 5%, line width is the default of 0.35mm. Point taken about strength of ABS/PLA and to be honest I'm just really printing these for fun with my son who is a massive Robot Wars fan, so unless he wants to start competing, PLA is probably fine and does seem to be a lot easier to print.


Thanks for all your advice.



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@kmanstudios Printer is only 1 month old probably no more that 20 prints total. I did notice some small bits of debris in the Bowden tube on extruder 1 and removed and cleaned it. Spools are new to me (around a month) but I take your point about warehouse time, though they printed fine when I first got them. The spool is still fairly full, but being conscious of the issue I did regularly loosen the spool during printing, enough to reduce friction when unspooling but not enough so it could tangle.


Where I might have gone wrong is using the same nozzle for PLA and ABS, when changing filament I've just been letting it feed through until the new filament is clearly running through the nozzle. Is using the same print core for PLA and ABS generally a bad idea?


Incidentally, after a failed print due to grinding, I can unload the filament fine, cut off the section from the grind onward and load it again and it will extrude fine every time during load, and start to print the first few layers fine.


I'll do some more reading on nozzle cleaning, thanks for the advice.

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The feeder may be too tight or too loose for your ABS.  You might have particularly soft (or conversely brittle) ABS.  I have a 6 year old spool of ABS that prints great.  No special storage - just sits in a box.


Switching from PLA to ABS is easy but switching back you might want to print hot (around 240C) for 20 minutes to get all the last bits of ABS out.  Or do a "cold pull" which is something you do from the menu that cleans out your cores nicely.


The picture below shows (left) not tight enought and (right) too tight feeder settings.  There is a screw in the top of the feeder.  Moving the line down makes it tighter.



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