This print sits in between the drive gear of your EZStruder and your groove mount bowden adapter, ensuring that the filament path is fully constrained. When I've printed with soft filaments, the most common cause of failure has always been the filament binding in the empty space of the EZStruder. This easy-to-install mod has eliminated that problem. Credit goes to guanu at SeeMeCNC for the original idea of installing a bowden adapter instead: http://forum.seemecnc.com/viewtopic.php?f=35&t=5298 His idea worked for me initially but my tubing wore out after awhile, so I created this as a more durable solution.

This print is tiny, so you're going to need a very well-calibrated printer to print this successfully. You'll need to print with a 0.25mm nozzle, and I printed mine standing upright with a brim. I designed the hole to be as large as possible but it's still going to come out undersized. You'll need to ream it out with a 5/64" drill bit (or something close to 1.8-1.9mm metric), and go SLOW because you'll melt the plastic otherwise. Once you have your print, disassemble your EZStruder and flip the lower portion to use the 3mm side. Then slide in the print, paying careful attention to the orientation - the print is not symmetric, so if you install it backwards you'll leave a gap and interfere with the engagement of the drive gear and roller bearing. Reassemble your EZStruder and you're all set!

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EZStruder