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If you are having trouble printing PLA, the first thing to check is the heatbreak. Make sure there is a gap between the heater block and the wide part of the barrel (see image). During assembly, you should screw the nozzle in as far as it will go, then back it out 1/4 turn. Then use the wrenches to tighten the barrel against the nozzle.


Once that is all in order, make sure your cam and adjust settings are correct. PLA is especially sensitive to adjustment (see this page and these instructions for details).

Hotend Assembly


Changing Filament

To understand how the cam dial works, see the How It Works page.


If your printer has a Load/Unload function, go ahead and use that. If not, heat the extruder and run it backwards. If this is too cumbersome, you can heat up the extruder, loosen the cam to position 4, and pull.

To load, again heat the extruder, and run the extruder motor forward until some material comes out the nozzle. With rigid materials, you can push the filament through manually. It may help to have the upper PTFE guide tube installed, which will put the filament in the correct location for loading.

You can use the print file below to load and unload filaments on the Wanhao Duplicator i3 (and similar). It will home, center, unload for a little while, wait 10 seconds, the load for a long time.


You will need to adjust your settings to get perfect prints with the Flexion extruder. First lower temperature as far as possible. Our Flashforge Creator Pro runs at 225°C. Then decrease extrusion by about 5% – the drive of the Flexion Extruder doesn’t slip like your stock extruder will, so it operates more “efficiently”, and you need less extrusion. And use a lot of retraction for flexible filament – at least 5mm at 60+mm/s. If you use Simplify3D, start with the profiles below for Ninjaflex (right-click, save link as):



Overhangs are possible with Ninjaflex, but they require cooling. Otherwise you get some pretty severe upward curling. Most printers these days come with cooling fans. If yours doesn’t, try these retrofits:


For Replicator-Style               For i3-Style



We designed the height of both Flexion versions to match the most common printers, so you shouldn’t need to change your Z-axis zero. But you will need to re-level your print bed. We recommend adjusting in real-time using a perimeter-print file. This is simplest on Replicator-style printers that don’t move the bed in the X- or Y-axis. Use Ninjaflex so you don’t have to wait for the bed to heat up. The STL file we use can be downloaded here:

Bed Level
Bed Adhesion


When printing Ninjaflex or other TPU material, bed adhesion is typically not a problem. Or, the problem is that it sticks too well. To stick: clean your print surface with alcohol or acetone. We recommend Kapton tape for the smooth finish (important if printing window stickers). When applying Kapton tape, make sure to first clean the surface that the tape is being applied to with alcohol or acetone. To remove: spray alcohol or acetone on the seam between the part and the print surface to help it release.

Peelable Support


Printing Ninjaflex is generally easier, but not so when removing support. Ninjaflex is sticky stuff, so typical support will be difficult to remove. But if the contact between the support and the part is only one trace wide, it can peel off very nicely. Model in your own support on overhangs, get it started peeling by making a slit with a scalpel, and pull it out. You’ll be printing custom phone cases in no time.


We recommend hanging your spools above your printer. This reduces the force that is required to pull out filament. If you mount your spools somewhere else and use a feed tube, then you may want to make a feed tube holder. There is an M3 threaded hole in the Flexion arm specifically for this purpose. A feed tube holder that we recommend can be downloaded here:

Spool Holders
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