Frictionless Spool Holder Hubs

Use these now instead  for 51-55mm as a new universal design I made -

used in this   - 

https://www.printables.com/model/1593296-mcs-2-space-saving-spool-and-buffer-system-for-mmu

Great for cardboard spools with rough rims and all spools! 

Get the  exact size for your spool's inner diameter center hole: 50, 52, 54, 56, 58, and 60mm and print two of that size.  I use a different color  (blue, green, red, etc,) for each size and keep them in a cardboard box next to the printer.  Use with the same 22mm bearings that came with your MMU spools, and the other hardware shown from any hardware store like Home Depot.  The goal is to have almost no friction at the spool and a center custom fitting bearing hub is ideal.  Although there are variable fit ones out there they take up too much space and I wanted my assembly to fit in a small space behind the MMU. This spins forever - see it in action spinning here.  https://www.youtube.com/shorts/Bp6n4agUFHE

Also look at this which is not only a slighty improved design but it also exactly fits almost 80% of the commons spool I use, especially polymaker, inland, hatchbox, and many cardboard spools. - https://www.printables.com/model/601604-polymaker-logo-spool-hub-with-mmu-bearings  and you can see a video of it here - 

This shows the details of how it is constructed. https://www.youtube.com/shorts/iDiCkVygh9k

Fits spools with 50-60mm inner diameter holes.  Uses standard 22mm skatebaord bearings or the ones that call with your MMU. You need two bearings per spool. This is intended to be  get the best performance out of you spools movement and spin as freely as possible:

• simple design that is functional

• almost no friction

• very strong and durable

• exactly fits the current spool - no adjustment needed

• as small as possible so many spools can be placed side by side in a line

• bearings can easily be moved in and out if needed to a different size

Print out a bunch of these pairs so you have a drawer of them to exactly match any spool you have with a perfect fit.  There are as small and compact as possible and allow more spools to be fit side by side, hence I did not design a larger adjustable system but a compact exact fit system. See picture.

The spacer is also here but you will need those use with this too so the spool doesnt rub against the sides of the vertical supports - https://www.printables.com/model/454846-spool-rod-spacer-for-516-inch-or-8mm-thick-rod-any

My final MMU setup is shown as one board with brackets and wood and metal rods where everything is one compact unit. You can also make individual spools or use these on 3D Printed spool holders that accept a metal rod. Here is the overview of the entire system I use in its final form: https://www.youtube.com/shorts/Ix5qLEh_60g

I decided to use a strong solid oak wood stand with drilled pilot holes for the 3 inch metal angle brackets, two 22mm bearings, metal hardware with 5/16 inch 4 inch long rods, 5/16 nuts and washers. It is a strong stand design and it spins forever.  Also see the spacers in my collection too that I use with these.  As long as you have a hole where you can attach a 5/16 inch 4 inch long rod then you can use whatever stand or attachment you want really.

• 4x 22mm standard bearings 7mm thick

• 2x 5/16 inch 4 inch long rods

• 6x 5/16 nuts 

• 2x 5/16 washers

• 3x 8 inch by 3 inch by .5 inch wood pieces. I got a 4x3x.5 foot oak one and cut it into 6 8 inch lengths, to make 2 double holders, for four spools

• 4x 3x3 metal brackets with screws, these come in stainless even but i got black ones

For the stand predrill all the holes for the brackets,. Drill two 5/16 holes for the rods one above the other. Offset the brackets a little so the screws dont collide in the middle. If you have a board you could just attach the vertical wood support to that too and put these all in  arow. 

Measure the inside diameter of your spools and print out the ones you need. I have here 52mm and 54mm but will add more.

If you need another hub size send me a note and I'll get it up here.

There is also a file here for is a spacer that you can resize in the Z axis (lock the other two) in slicer to make as long or short as you want so the spool. I made several of these at 5mm, 10mm, and 15m lengths.

Other useful items:

Short spacer bar  - https://www.printables.com/model/460874

Riser and open coupler - https://www.printables.com/model/432647

PTFE Adapter connectors - https://www.printables.com/model/416215

PTFE Angle bracket (this item) - https://www.printables.com/model/470374