Filament Extruder Puller

I needed to make a puller for my [filament extruder project](https://medium.com/endless-filament). I tried wingmaster's [one](https://www.thingiverse.com/thing:677144) which is a nice and compact design but in the end I had one too many issues with it so I decided to create my own based on Making Stuff's [design](https://www.youtube.com/watch?v=gyy7zwMgzdw) (which I couldn't find the STL files for).

I like this design because it's simple, requires much less material and can accommodate many different rubber bushing sizes (all you have to do is change the diameter of the shaft couplers).

I have yet to test if this actually controls the filament diameter but I will update this when my extruder is complete and tested.

BOM:

- 1 x NEMA 17 motor
- 2 x Rubber Bushings (mine are 57mm long with 25mm outer diameter and 12mm inner diameter)
- 2 x Springs (~50mm) (initially I only had one but this caused the top rubber bushing to be at an angle and the filament would veer to one side