608 Roller Bearing

Description

This 608 bearing is entirely made of filament, easy to assemble and customizable. It is robust, tight, and runs very light. The parts are easy to print on any regular 3D printer with a 0.4 mm nozzle.

This bearing uses filament as rollers. Filament is very tightly tolerance and consistently round without imperfections, which makes them great rollers. This design borrowed the neat idea to use filament-as-rollers from @firstgizmo's design (https://www.printables.com/model/1063080-608-bearing) 

Advantages

This assembled bearing is more practical than many Print-in-Place designs:

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

• You can inspect & finish the running surfaces if needed.

• You can easily use different materials for the rollers.

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

Design Details 

• Fully functional roller bearing, with very low friction.

• It can handle decent lateral loads, with integrated low friction slide surfaces.

• Drop-in fit for any light 608 bearing application, like spool holders.

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

Printing instructions

All Combined STL File

The "All Parts - Print Layout" STL file is ready to print. It has all the parts in print orientation. The Inner Race is the Loose variant and should work for most. If it is a bit loose try a tighter Inner Race, see below.

Individual STL Files for different Configurations

There are individual STL files to configure the bearing to your liking and application:

• Outer Race & Cage are always the same.

• Cap in Regular (with windows) and Closed variants.

• Inner Race

  • Three sizes (roller clearance): Tight (1.75 mm), Standard (1.8 mm), & Loose (1.85 mm).

• Cutting Jig

• Assembly Tool

Material Choice

 PLA recommended, other materials should work but haven't tested it

Slicer settings

• 0.4 mm nozzle (larger won't work)

• 0.15 mm layer height

• 2 perimeters, 25% infill

• key (Prusa)slicer settings that worked best:

  • Scarf joint on Contours 

  • Scarf joint on Inner Perimeters

• Part orientation on the build plate:

  • The Inner Race is asymmetric, orient it with the chamfered side down

  • The other three parts are self-explanatory

Post processing

Check the roller running surfaces on the inner and outer race for bumps/printing artifacts. If necessary, run a small file on both surfaces to take off any artifacts and smoothen the surfaces a bit.

Roller preparation

Cut 11 rollers to 4.3 mm length (anywhere in the range of 4.0 to 4.6 mm works fine). I used PETG filament for the rollers. It gives the bearing a bit softer feel and it prevents binding if the bearing sits under load for some time or at higher temperatures.

Use the Filament Cutting Jig and a small utility knife to cut the Rollers. Be careful not to cut yourself.

An interesting alternative is using FLEX filament for the rollers. It makes the bearing quieter, with a little more friction.

Bearing Assembly

1. Place the Outer Race down

2. Place the Inner Race - makes sure the chamfered side is down

3. Place the Cage, with the ring down

4. Place the Assembly Tool, use a piece of filament to locate it in a roller hole  

5. Place 10 Rollers (small pliers work well), they should drop in easily

6. Remove the guide filament, place the last Roller and remove the Assembly Tool

7. Slide a tool over the edge of the Outer Race; no rollers should protrude

8. Place the Outer Cap on the bearing assembly, and press it down to snap it in place

Lubrication is optional, it is not needed but could make the bearing run a little nicer

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

Step 1, 2 & 3                               Step 4, 5 & 6                             Step 7                                       Step 8

Exercise the bearing

Exercise the bearing a few turns to run it in. You should be able to see the roller run through the windows in the Outer Cap. If it is too tight try printing an Inner Race with a larger gap.

Variants

There are three Inner Race parts for different roller gaps (bearing tightness): 1.75 mm, 1.80 mm & 1.85 mm. For me 1.85 ran very well & light, 1.80 mm runs too and is a bit tighter.

There are two Outer Caps, with and without Windows.  Use the closed outer cap to prevent dirt/dust getting into the bearing, and keep any lubricant in.

Designer's note

I got back to bearing concept design after a few years and designed a few assembled bearings, also have a look at these:

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

https://www.printables.com/model/1668708-606-mini-bearing-with-rollers-cage-not-pip

Revisions

Version 1.0 - March 22, 2026: Initial public version.

Version 1.1 - July 11, 2026: Added filament cutting jig and assembly tool.