Flexystruder jammed?

Flexystruder seems to be jamming. I have a lulzbot mini, prints great with HIPS. I purchased the flexstruder for the mini, performed the installation and printed the key chain and that looked great; then tried to print with both semiflex and ninjaflex 3mm and the the tool head makes a sort of stuttering sound and no filament extrudes. I turned the motors off and manually tried to advance the filament when appropriately heated and no go, seems as is the tip is jammed? ANy ideas on how to fix this?


Have you tried pulling the filament out via manual retraction with the motors off? The filament could have been ground.

Check that the screw on the side of the flexystruder is pressing the softer semiflex filament against the hobbed bolt. The screw acts in place of the idler of the normal extruder to clamp the filament against the hobbed bolt. If not clamped tightly, the filament may not advance.

I suspect the HIPS is a harder filament requiring less clamping against the hoobed bolt… which is why its probably printing properly.

Hope that helps!

Thank you both and to customer support at lulzbot. It will be a bit hard to describe, but kc_chen00 was pretty much right on.

First off to be clear, I did not put any HIPS through the flexystruder; I read before hand that it only prints the flexible filaments, and in fact once you let Cura know you have the flexstruder installed, it only gives semiflex and ninjaflex as options, not that that would stop you from loading it anyway, but I think I wasn’t clear about this. I just wanted to indicate that the rest of the mini worked fine prior to changing to the flex.

So I called customer support and discussed the situation and the rep told me it was likely that the alignment between the upper 3D printed component of the flexy and the metal extruder part was out of whack. He instructed me to remove/retract all of the flexible filament, allow the it to cool down and use a bit of HIPS to align the upper and lower units. Then bolt the two pieces back together tightly and then reassemble everything else( you really have to take the whole flexy apart to do all this! ) and reattach it. . . and viola!

So I did all this and it worked, and then bam . . . same problem again. I went through it all again and then viola, I am on print 5 or 6 now since the second round of reassembly and realignment and everything is printing well!


  1. I think that the flexy came to me a bit on the loose side, and performing the test print caused enough vibration to knock the pieces out of alignment. I think it was just bad luck on my part as I have not seen similar concerns on the forum.

  2. Call customer support, they are great!( read over the forums first )

  3. Sapphire semiflex is absolutely beautiful, get a flexy head and print some just to print with it!!!

So, based on this, if I get the flexystruder I will have to switch back and forth to print flexible plastic and normal stiff plastic? How hard is it to swap out the extruders?

Yes, it is recommended to swap tool heads. It takes me about 5 minutes, it’s really quite easy to do. I don’t find a lot of need though, I print mostly with harder materials, so I run the standard tool head most of the time.