Pivoting filament spool holder for cube frame direct drive printer

A low friction filament roller that points in the direction the filament is pulled. Direct drive extruders, such as in the Sovol SV05, move around with the hotend and travel over the full extent of the build platter. The filament can be snagged or may unwind during the build. This design raises the spool up so that the filament can easily reach the extruder without snagging the wires to the head.

It makes use of a small paint roller for both the rolling spindle and for the bracket that can twist to align the roller as it gets pulled.

What gets printed are the endcaps for the roller and a mounting that fits a 2020 extrusion as found in the Ender 5 and Sovol SV05 design or generic printer like Ender 3 which would use the 20mm roller hinge.

What gets bought are 

• a 4” (mini) high density foam paint roller, the long handle version so that it can hold a spool. These are available from places like Home Depot, Harbour Freight and online. I bought mine at the Dollarama. Look at the handle and length in the pictures, those I know will work. The shaft diameter is 5.73mm (0.225") which will fit properly into the mounting bracket.
• 2 foam rollers (unless your roller comes with 2 or more). The endcaps depend on the dimensions of the tube in the foam refill. We use two to support both ends of the rolling centre.
• A short section (80 to 85mm) of 1 ½” or 1 ¼” ABS pipe. The 1 ¼” is preferable because it allows slightly larger flanges on the end to keep the roller from falling off the edge. 
• One short ¼” x 20 screw
• 4 M5 x12mm screws and T nuts for the 2020 extrusion
   

Approximate sizes:

• The 1 ½" ABS pipe has an OD of 48mm (1.9") and ID of 40mm 
• The 1 ¼" ABS pipe OD is 43mm, ID is 35mm.
• A 1kg filament spool inner hole diameter is usually 50mm to 53mm and the width of the spool is 60mm to 65mm

Easy part:

• Print the endcaps and mounting bracket
• For each foam roller, cut the foam off the inner tube and cut the tube short, back to where the part that grips the rod ends. Keep this foam, you may want a piece of it to damp the spool's movement if it rolls too easily for your liking.
• Cut a 3 ½” piece of the tube, make sure the ends are flat and perpendicular to the tube.

Not so easy part

• Pull the plastic handle off the rod, this will be difficult, I heated the rod with a propane torch till it became loose enough to pull out. Don’t damage the section of rod leading into the handle, this needs to be straight and smooth to pivot nicely in the mounting bracket.
• Modify the bends in the rod so that a 200mm spool will fit. 
  • No need to change the first bend.
  • Straighten the second bend
  • Invert the 3rd bend

To bend the rod more easily, I heated the areas with a small propane torch till the steel turned a light brown colour and bent easily at that spot by hand. My first attempt I used a hammer and a vice to do the bending and straightening. This works but is far less exact.

• Cut the long end shorter, leave 30mm of a straight section that will fit into the mounting bracket

Final assembly

• Insert cut off tubes into the endcaps. If you left some foam on the tube this will help retain the tubes in the endcaps. Glue them if they're too loose for you.
• Insert the endcaps into the ABS pipe section that you bought.
• Assemble onto the remains of the roller, the section will be shorter than the roller that you just made but will work , the metal rod just won’t protrude from the endcap.
• Once the centre spindle looks good and rolls nicely, glue the endcaps onto the tube.
• Check the cut off and filed end fits into the mounting bracket and rotates smoothly. Add some lubricant if it needs it. You may heat up the shaft to loosen the fit a bit.
• Screw the ¼”-20 screw into the bottom of the mounting bracket. This is to stop the shaft dropping through and to prevent the same shaft from wearing through the print material over time. I cut mine short to make a grub screw but this is not necessary if you don't mind it sticking out the bottom.
• Fit the mounting bracket onto you printer as you feel best. It can be added to a single 2020 if you need to, just check the long part doesn't interfere or you can use the 20mm hinge.
• As a bonus, use the handle for a file. Heat the tang of the file and insert it into the handle whilst still hot.

Too loose, filament unwinds itself? Use some foam, felt or a brush with the bristles shortened clipped or glued to the holder to brush against the side of the roller to add a bit of friction. Adjust to taste.

Printing
I used PLA, 3 walls, 15% infill, 0.28mm layers, no supports and Cura's “exclusive” setting for slicing tolerance (experimental). Position on the bed is as shown in the .stl files.