Ender 3 tensionable extruder arm

Replacing the stock arm with this tensionable arm on the Ender 3 / CR10 / etc extruder/feeder can give you much more consistent results in 3D printing. The stock feeder doesn't get much tension from the weak springs that come with these printers.

This allows you to adjust the tension until you get real bite (should be visible on the filament but not deforming it). You can do a quick test by seeing if you can easily spin the feeder gear with filament preloaded -- if it slips with light force t