Jams and filament chewing, retraction settings

Posting this in case it helps anybody else who has problems with failed prints due to the extruder hobbed bolt chewing through filament. I’ve been having problems with this for several months on my TAZ. There are a lot of posts on this forum and elsewhere about this issue, and lots of suggestions about how to fix these problems. However, as far as I can tell, very little has been said about the effect of retraction settings on extruder jams and filament chewing.

Anyway, I’ve gone through a lot of the suggestions over the past months with mixed results. At times I’ve had a lot of successful prints, and other times I have one failed print after another with the filament chewing problem repeatedly. Most recently, I was trying to print the fan shroud for building a new extruder assembly. Over the past couple days, that print failed close to 10 times with the filament chewing problem. I finally stumbled on trying to tweak retraction settings. By lowering the retraction distance and raising the minimum retraction travel distance, I got the shroud to print twice perfectly.

Upshot is, if you are having problems with filament chewing, and especially if your hot end does not seem to be clogged, then take a look at your retraction settings.

Hope this helps somebody…

I guess retraction settings are the reason for most of the extruder jams described here, but I have no chance to prove this… If thats true, most of the people having this issue will use Cura as it’s the “Queen of retraction amount”. See the small part about infill in my Slicer comparison

Yeah, I was thinking a lot of the extruder jams people experience were due to retraction settings. Tweaking those setting made an immediate and drastic impact for the better for me. Weird though that this is hardly mentioned anywhere.

Nice comparison. I’ve not been using Cura, been using Slic3r and Simplify3d. Guess I’ll stick to those for now.

Dave, can you post up some of the values you used for retraction parameters??


Tim in D


Sure, The original settings I had in slic3r were:

retraction length: 1.75mm
lift z: 0
speed: 20mm/s
extra length on restart: 0mm
min travel after retraction: 2mm
retract on layer change enabled
wipe when retracting disabled

With those settings, I was getting constant jam and filament chewing on some models. I changed these, and was able to print those models without problems:

retraction length: 1mm
min travel after retraction: 5mm

Note that for other models that I have not had problems printing, those adjusted settings seem to cause some minor print quality issues. So it seems like those settings can be a trade-off between avoiding jams and getting the best print quality. But if you run into the filament chewing issue, look at whether the print is doing a lot of retracting, and if so, tweak those settings.