A fairly chunky extendable filament roller.

I created this because I didn't like the way my filament spool was sticking and dragging on the regular spool support or the height of the machine with the spool on top and I couldn't find an existing model I liked.

The rollers are wide to accept a variety of spool widths and cope with spools with warped sides.

I has an end roller base and an intermediate base if you want to have multiple spools ready to go or if you have a dual extruder machine. 

The rollers themselves are in 2 parts with a joiner to connect them. The square hole in the rollers is modeled at 12mm square by 25mm deep. The joiner is modeled at 11.8mm square by 48mm long. Print the roller halves end on to get the best roundness of the outer and the bearing pocket. Print the joiner on it's side for best snap strength. If you get any elephants foot on the joiner sand or file down to make a good fit in the axle halves. If the joiner is not a good tight fit use glue. I recommend printing the Rollers and Joiners on a raft to avoid elephant foot making assembly more difficult.

The rollers use 8x16x5mm bearings such as www.amazon.co.uk/gp/product/B07CJ86XJ9 needing 2 per roller or 4 per spool.

The bearings are a snap press fit into the ends of the roller halves and onto the stubs on the bases. The press fit is very tight to hold the bases together and best done in a proper press of some sort or maybe a pillar drill or large vice. It may be difficult to assemble without some sort of press able to open to at least 100mm for single or 190mm for double roller version.  I found that the opposite stub was mushrooming while pressing in the first on the center base so I used a socket to bridge over the stub while pressing.

Print with whatever slice thickness and settings works for you, I printed with 0.2mm.

It will need supports on the bases, I used Tree supports. 

For extra strength I used Support Blockers in Cura to increase the infill density to 100% around the stubs on the bases. This is probably also necessary to take the force of pressing the bearings on.

Base underside is plain for either sticking down or just leaving loose beside machine. 

Have added Gcode files, selected Ender 3 because I think my machine is a Ender 3 clone