Ultimachine sells large, 5 lbs (2.3 kg) spools of filament. These spools are a bit large to put on a lazy susan or mount on the back of many 3D printers. Consequently, I designed this spool core to be part of a support system for these large spools. The core acts as a heavy duty spindle to support the spool and to present two press-fitted 608 skate bearings through which an 8mm diameter axle may pass to hold the spool. The spool rotates around the axle with ease owing to the bearings; this should put less strain on your extruder feed mechanism as it presents less static friction than other possible spindle systems.
The press-fitted 608 skate bearings may be locked in place using an M3 nut and bolt acting as a set screw.
A fully parametric OpenSCAD source file is also provided.
- 2 x M3 nuts (optionally, 4 total)
- 2 x 10mm long M3 bolts (optionally, 4 total)
- 2 x 608 skate bearings
- 1 x 8mm diameter (max) rod/shaft/axle of length at least 120mm (the spool core is 114mm long)
- I printed my cores in PLA: 0.3mm layer height, 2 shells, 15% infill.
- The bearing cavity on the flanged end of the core may need a little cleanup: its "roof" is bridged and there may be some drooping filament strands depending upon your slicer, printer, and plastic.
- Once printed, press-fit in a 608 skate bearing on each end.
- Slide the core through the filament spool.
- Affix the non-flanged end with two M3 nuts and two 10mm long M3 bolts. Drop one nut in one of the two slots and then screw in a 10mm bolt from the side. Repeat for the other slot and bolt hole. The M3 bolt heads should stand out a bit: they are what are keeping the core from coming back out of the spindle. If the 608 bearing is a little loose in its cavity, then you can tighten down these M3 bolts to snug it in place.
- If the 608 bearing on the flanged end is a little loose, you can use an M3 nut and an 8 or 10mm M3 bolt to hold it in place. The bolt will act as a set screw.
- Slide your shaft/axle/rod of choice through the bearings. I'm using some 8mm linear rods I had lying about.
- Support the shaft/axle/rod however you see fit.
- I made the slots for the M3 nuts a little wide (diameter of an M3 nut, not the narrower but sufficient 5.5mm width). That was to ensure that for most printers and plastics you can easily drop the nuts in and also get them back out again. However, this means that the nuts may spin while you thread the bolt in. If that happens, just slide a thin slotted screwdriver down one side of the slot to hold the nut in place while you thread in the M3 bolt. (Actually, I used the end of a wire tie.) Alternatively, you can change the value of the m3_nut parameter in the OpenSCAD source file and regenerate the STL.