feeder tension and retraction with ABS - UM3E

[daj1u06 0]

Hi, we have been getting largely great and consistent results from our UM3e with ultimaker PLA and PVA with feed screw tension set  to middle point and standard Cura settings for fine quality. Recently I had to do a couple of prints with multiple small columns using ABS. The first one worked great. The second one (about 20% larger all round) failed a day into the run. As you can see from the photo,  it had partially printed the larger area colums but not the smaller ones and the filament in the bowden tube was well and truely mashed up, so suspect misfeed rather than blockage.

 

I guess the different filaments have different strengths so, as a general rule, would one want to increase feed tension when printing in ABS (?softer) to force the ABS through or decrease to prevent damage to the filament which then causes misfeed?

 

What about retraction? with all those small columns? I guess that it is pushing and pulling a lot and this could contribute to mashing a softer filament? Should I reduce or turn off retraction? Because of the linear geometry, it would be easy to remove any overspill from non retraction after printing.

 

For those intersted, it is a jig for slicing up prostate glands removed from patients, prior to embedding them in wax for pathological examination!!!!

 

As these are quite large and time cosuming and use a lot of plastic, I'd rather tweak setting based on expert opinions. Thanks for any suggestions,

 

DAJ

[Brulti 177]

I never had to change the tension, and I printed things with the whole array of UM materials for tests when I got my UM3E.

ABS should print as well than PLA or other with medium tension. As @SandervG said in another thread, there is no reason to change the tension in the feeder.

 

From the pictures and what you said, there was obviously a misfeed for some reason, since the filament was ground up, and it also looks like a missed layer as well. Have you checked the slicing for the bigger version in CURA using the layer view? There may have been a bug during slicing.

 

I'd suggest doing a thorough cleaning of the feeder, to remove all the dust from the ground up filament, and also of the bowden tubes, just to be on the safe side. Check your filament for any defect, is it UM filament or another brand? And look carefully at the model in layer view in CURA before trying another print, to make sure there is no slicing error or problem with the model.

 

As a side-note, I'm going to add another reason to be baffled by all the uses for 3d printing! A jig for slicing prostate glands prior to examination. Awesome! ^^

[SandervG 1,521]

Yes, I would not recommend to change the tension on the feeder. If it would show to be necessary, it is probably a band-aid for a different problem. 

It looks like your print got interrupted quite abruptly, but it recovered after. I think it is not something you need to change in Cura, but you may have had the misfortune of some dirt in your nozzle / print core. Did you use Ultimaker ABS? The very cheapest of materials sometimes can have chunks of trash in them, which don't melt properly and can cause a clog. Like @Brulti says, perhaps clean your feeder to see if there is dirt in there that might got dragged up with some filament. Was the filament easy to retract through the bowden tube after the failed print? (if not, you might want to inspect the diameter, perhaps it was inconsistent and there was a thicker section in there). 

I don't think it would benefit your print to disable retractions and I don't think it should be necessary. How big is it in total? 

 

[daj1u06 0]

Thanks for the comments and suggestions, it was all genuine ultimaker materials, the poor quality side bits were originally very loosely attached but are incomplete, with incomplete infill and side walls and fell away so it was a sudden misfeed at that level in the model, whatever the cause, but that doesn't explain (to me at least) why the shorter columns appeared to have not gotten printed at all but the larger, outer ones were at least partially printed (there didn't seem to be enough "spatter" on the print bed to suggest these had been at least partially printed but then pulled or knocked off.

 

The material unloaded no problems. I did gently pull it from the feeder at the start of the unload to give initial traction as I was pretty sure that it had ground itself down at the feed wheel (it had). A colleague then changed printcores and did a PLA print on the same feeder without issues, so it wasn't stuck in our dedicated ABS printcore and the feeder and bowden tube aren't jammed with crud.

 

The whole thing is some 93 x105 x 65mm high, the previous, successful, one was slightly smaller at 70 x 120 x 55mm high (your prostate enlarges with age, whether pathological or normal so I have a set of 5 to print in different sizes!) Agreed its a somewhat niche print job, but thats what makes it fun (for us at least) :-)

 

I'll check the printcore again and look at the model again in cura when I can next get onto the machine.

 

Thanks folks,

 

DAJ