608 Bearing - fully printed, easy assembly

Newer Version available

This bearing works well but I revised the cap interfaces to get a tighter fit and better lateral fit, see:

https://www.printables.com/model/1715172-a-better-608-bearing

Description

This 608 bearing is entirely printed and an assembly, not print-in-place.  The bearing is easy to assemble and customizable for a perfect fit & function. It is robust, tight, and runs very well. The parts are easy to print on any regular 3D printer with a 0.4 mm nozzle.

Short instructions

• PLA recommended

• Print with 0.4 mm nozzle at 0.15 mm layer height

• Random scarf joints on contours & inner perimeters

• Control/check the rollers for elephant foot

• Assembly sequence; Outer Race --> Inner Race --> Cage --> Rollers (with needle nose pliers) --> snap on Outer Cap snap --> snap on Inner Cap 

Full description & instructions

Advantages 

This assembled bearing is more practical than Print-in-Place designs (or Bushings):

• It has tighter fits, since it doesn't require printing clearances (unlike PIP)

• You can inspect & finish the running surfaces if needed

• You can use different materials for the rollers (including FLEX!)

• You can optimize the rollers fit for your application, balancing tightness and friction. For that you can disassemble the bearing and change out the rollers (different sizes are included in the STL files).

Application Details 

• Fully functional roller bearing, with a proper cage to separate rollers

• It can handle decent lateral loads

• The hollow rollers provide a little bit of elasticity; more traditional solid rollers are also available

• Drop-in fit for any light 608 bearing application

• Not intended for high velocity/force/heat applications; use a normal, purchased 608 bearing for that.

Printing instructions

Material choice

For Races, Caps & Cage: PLA recommended, other materials should work but haven't tested it

For the Rollers:

• PLA works fine, it can be a bit noisy

• PETG is recommended, it provides a nicer feel and prevents binding over time under load.

• FLEX/TPU also works! It makes the bearing dead quiet while it still runs (with a bit more friction). Great option if you need a very quiet bearing.  

Slicer settings

• 0.4 mm nozzle

• 0.15 mm layer height

• 2 perimeters, 15% infill

• No supports needed

• Key (Prusa)slicer settings that worked best:

  • Scarf joint on Contours 

  • Scarf joint on Inner Perimeters

• Check/control for elephant foot, especially the rollers

• 16 minute print time on a Prusa Mini or Mk4 if printed all parts at once

Post processing

Check the roller running surfaces on the inner and outer race for bumps/printing artifacts. You can run a small file on both roller running surfaces to take off any artifacts and smoothen the surfaces if needed.

Assembly instructions

Assembly Steps

1. Place the Inner Race & Outer Race down 

2. Place the Cage, with the ring down

3. Place 7 Rollers (small needle nose pliers work well)

4. Place & snap the Outer Cap on the bearing assembly

5. Place & snap the Inner Cap on the bearing assembly

Assembly Notes

• Do not lift the assembly before both Caps are snapped in place! The bearing will fall apart, and the rollers will go everywhere. You can place the Inner and Outer Race on a piece of painter's tape to keep them together during assembly.

• Lubrication is optional, it is not needed but makes the bearing run a little nicer.

  Step 1                                         Step 3                                           Step 3 complete                     Step 6 

Exercise the bearing

Exercise the bearing a few turns to run it in; you should be able to see the rollers & cage move relative to the inner and outer race.

Disassembly steps

You can disassemble the bearing without damaging any parts (to change out rollers): 

1. Remove the Inner Cap: use a small flat head screwdriver or other pointy tool to push the Cap out from the inside (to prevent damage). There is a small gap between the Cap and Inner Race for the screwdriver head to catch.

2. Remove the Outer Cap: slide a small knife in the gap between Cap and Outer Race and give it a light twist, the cap should come right off. Be careful not to cut yourself. 

Variants

Included are a few Roller variants:

• Solid & Hollow

• Standard, Tight (+0.05 mm. diameter), Loose (-0.05 mm. diameter)

You can also XY scale the rollers in the slicer to optimize fit.

Revision History

Version 1.0 - March 20, 2026: Initial public version.

Version 1.1 - March 23, 2026:

• Increased wall thickness on both Inner Race and Outer Race for a bit for more consistent printing,

• Reduced nominal roller diameter from 3.8 to 3.6 mm.  

• Added a disassembly groove to the Inner Cap.

Version 1.2 - April 9, 2026:

• Slight optimization for better lateral stiffness 

Designer's notes

Filament Roller 608 Bearing - I built on this design and made a version with filaments as roller, inspired by the neat idea by @firstgizmo. It runs super light and it's similarly easy to assemble.

606 Mini Bearing - I was curious if the concept would go smaller and the answer is yes! This 606 bearing is only the size of a dime and runs just as well.