So I've been trying to 3D print a flexible nose for the Billy Bomb and my printer extruder is driving me nuts. It makes it about 3 to 5 minutes into the print job and then just spews the filament out through a gap in the side of the extruder instead of down into the hot end. And from looking around, this seems to be a fairly common challenge with printing flexible filaments, with the solution often being "get a new extruder".
What I'm not finding a lot of information on is "what extruders DO work well with flexible filaments and a Prusa i3 style machine". The Flexion has come up a couple times, but honestly it's usually the Flexion rep chiming in to say "hey, our product works great!"
Does anyone lurking on this thread have any experience with this before I figure out how to get one of these into my hobby budget?
A prusa i3 based machine should be able to print flexibles so long as you know the right tricks.
Number one in your case would be adjusting the filament clamp tension on your extruder. For soft flexibles you want to make sure that the screw tension is just enough to grab the filament. Too much more than that and stuff will squirt out the side. The higher the shore hardness of the filament, there more clamping pressure can be tolerated.
Secondly, slow down your print speed. Start at something like 20mm per second. Once you get successful prints you can boost that number.
Third, make your first layer height higher. You need to give flexibles more space to lay down on the bed at the begging. Squishing it into the bed creates backpressure which can jam up the extruder, or make filament pop out the side.
Fourth, set the temp at the high end of the range to start out. More temp means it will flow easier.
And lastly, disable retraction. You may be able to turn i t on after more tuning, but start out with it off. To counter stringing, find the option in your slicer that tells it to avoid crossing outer perimeters