Bearings are silent but vital components: from the smooth movement of axes to the precise rotation of pulleys and rollers, every machine contains dozens of them. Choosing the wrong bearing means excessive friction, noise, premature wear and loss of precision. In this guide we look at all the types used in 3D printing and CNC machines.
Radial ball bearings: the basics
Radial ball bearings are the most common of all. They consist of an inner ring, an outer ring and a series of balls that roll between the two rings, reducing rotational friction. The abbreviations indicate the size and type of shielding: ZZ indicates double metal shielding (protection from dust, the most common), 2RS indicates double rubber seal (better seal, slightly more friction), and "open" indicates no shielding (maximum speed, but exposed to dirt).
Most used sizes in 3D printing
|
Code |
Int. diameter |
Diameter ext. |
Width |
Typical application |
|
608ZZ |
8 mm |
22 mm |
7 mm |
V-slot wheels, pulleys, guide rollers |
|
625ZZ |
5 mm |
16 mm |
5 mm |
GT2 pulleys, idlers, wheel guides |
|
624ZZ |
4 mm |
13 mm |
5 mm |
Extruders, filament guides |
|
623ZZ |
3 mm |
10 mm |
4 mm |
Micro guides, compact systems |
|
695ZZ |
5 mm |
13 mm |
4 mm |
Guide wheels, lightweight systems |
|
F688ZZ |
8 mm |
16 mm |
5 mm |
Flanged version of 688, pulleys |
|
F695ZZ |
5 mm |
13 mm |
4 mm |
Flanged version, easy assembly |
|
MR105ZZ |
5 mm |
10 mm |
4 mm |
Micro applications, pivot |
Linear bushings: straight motion
Linear bushings allow straight-line movement on smooth chrome-plated shafts. They contain recirculating balls that roll on the shaft, ensuring low friction and good precision. They are the standard for Cartesian 3D printers with guides on round shafts.
|
Code |
Shaft diameter |
Ext. diameter |
Length |
Notes |
|
LM6UU |
6 mm |
12 mm |
19 mm |
Small printers |
|
LM8UU |
8 mm |
15 mm |
24 mm |
Standard 3D printers (Prusa, Ender) |
|
LM8LUU |
8 mm |
15 mm |
45 mm |
Longer, more stable version |
|
LM10UU |
10 mm |
19 mm |
29 mm |
Lightweight CNC |
|
LM12UU |
12 mm |
21 mm |
30 mm |
CNC, large format printers |
|
LM16UU |
16 mm |
28 mm |
37 mm |
CNC medium |
|
SC8UU |
8 mm |
- |
- |
Bushing with integrated support |
|
SCS8UU |
8 mm |
- |
- |
Long bush with integrated bearing support |
Needle roller bearings and thrust bearings
Needle roller bearings (type HK0408 or HK0608) are compact, high radial load-carrying bearings used in some extruders and filament feed systems. Axial bearings (type 51100, 51102) handle loads in the axis direction and are used in platter adjustment systems and pressure mechanisms.
Polymer alternatives: bushings Igus
Self-lubricating polymer bushings (type Igus Drylin) are a silent, maintenance-free alternative to linear ball bushings. They require no lubrication, are dirt-resistant and offer quiet operation. The trade-off is slightly higher static friction. They are very popular at community Prusa and Voron.
Maintenance Tips
Shielded ball bearings (ZZ) require little maintenance, but benefit from a drop of light oil every 6-12 months. Linear bushings should be lubricated with lithium grease or machine oil every 3-6 months, or more frequently with heavy use. Replace bearings at the first signs of play, noise or roughness: a worn bearing compromises print quality much more than you think.
Bearings and bushings at DHM-online
At DHM-online you will find the entire range of bearings for 3D and CNC printing: radial and flanged ball bearings in the most common sizes, standard and long linear bushings with or without bearing, precision chrome-plated and ground shafts, and complete kits for the most popular designs.
Browse the Mechanical Components section to find everything you need.
