3TSS: 30mm Tube Spool System by wavexx

Last crawled date: 3 years, 4 months ago

3TSS: 30mm Tube Spool System
This is a complete solution to convert a regular 30mm tube into a horizontal/vertical (suspended!) spool holder for one or more rolls.
It includes:
Fixed spool hub adapter
Axial bearing spool adapter using 6mm softair pellets
Filament guide for perpendicular feeding (doubles as clamp)
Plain 30mm tube clamp
M3 drill helper (for the safety endstop)
Flush tube cap
Requires:
30mm tube of any lenght (in this case, a 30x500mm foot used for furniture, ceiling mounted)
M3x10 cylinder head screw (for the safety end-stop)
M5x20 hex-head + M5 butterfly nut (for both the clamp or filament guide)
32 6mm softair pellets (for the axial bearing)
01/2021 Update
Updated filament guide (filament guide v2): improved bend and larger internal diameter. The hole now fits an (optional) 4mm bowden tube, press-fit. The bowden tube reduces friction with some materials (such as CF filaments).
Printing
All parts are optimized for a 0.2 layer height, 0.4mm nozzle, 2+ perimeters.
PETG or ABS is highly recommended for the simple clamp and for the filament guide (due to the flex applied by the butterfly nut). I've used PETG for all parts.
No supports are required, although the filament guide could use a little to improve the quality of the lower part of the upward bend.
Very good dimensional accuracy is required for the axial bearing in order to have good loading strength.
Safety gravity end-stop
Since I've mounted my tube suspended, I've included a safety end-stop in the design. This can be omitted in horizontal or floor-mounted setups.
An M3x10 socket-head screw needs to be drilled at the end of the tube. A drill-helper is included to make a perfectly centered/perpendicular hole. When drilling remember to leave enough space for the cap.
All parts have a special slot which fits the head of the screw when aligned. When inserting components into the suspended system you should turn each part slightly so that the safety can catch a loose part.
Axial bearing
In most cases, for a single 1kg spool, the fixed spool adapter is enough, prints faster and uses less material as well.
For heavier spools, or in a vertical design, the friction required to pull the filament can become significant. In these cases the axial bearing can offer butter-smooth motion:
https://youtu.be/TrgeDNtn97A
I checked my softair pellets to have an effective 5.95+/-0.01mm diameter. The inner spacing is 6mm exactly. With these tolerances I tested up to 10kg of axial load without issues, so a single axial bearing can be used for up to 2-3 spools. The radial loading is probably even higher.
If you need higher loads (for more spools) use multiple bearings separated by a regular clamp.
In any case, on a vertical system, the axial bearing is only needed on the bottom of the spool. A fixed adapter is always sufficient on the top since it just needs to keep the spool balanced.
When using a safety end-stop, the radial bearing needs to be aligned in order to be removed. There is a special notch on the outer perimeter to indicate where the opening is, and whether it is aligned:

Axial bearing assembly
To assemble the axial bearing first combine the bottom and top parts together. Flip the bearing so that you're looking at the bottom. Align the special notch, then rotate 20 degrees counter-clockwise (until a regular notch aligns) to find the special loading slot:

Push from 30 to 32 6mm airsoft pellets. Some force is required to push the pellets in.
Once about 3/4 of the pellets are inserted the two parts of the bearing should be locked together and cannot be separated anymore.
Clamp / filament guide
The clamp can be seen in detail here:
https://www.thingiverse.com/thing:3418776
The filament guide uses an identical design.Do not over-tighten these: very little tightening is actually required.
Tube cap
The tube cap is designed to fit an inner diameter of 28mm and might not work for all tubes. It can be scaled down, but not up, since the border of the tube needs to be perfectly flush in order to let the components pass.