Ball bearing
Vitamin
Ball bearing are used for low friction movements across an axis. | |
Wikipedia | Rolling-element bearing |
A ball bearing is a bearing used for low friction movements across an axis. They are cheap and widely available, mostly from the skateboard industry.
Lubrication
Ball bearings are usually closed and have their own lubrication, so no additional lubrication is needed.
Name
The first digit of the model name refers to the kind of bearing, the second digit to its robustness. The third digit is usually the bore size in mm. Then follows the bearing type letters.
Types
There are several types of ball bearings:
Abbrev. | Type | Notes |
---|---|---|
Z | Shielded, single | |
ZZ | Shielded, double | Sufficient for most RepRaps. |
RS | Sealed, single | |
2RS | Sealed, double | For keeping out generated dust and grit (e.g. from a Milling and Drilling Head) |
V | Non-contact seal, single | |
VV | Non-contact seal, double | |
DDU | Contact seals, double | |
NR | Snap ring and groove | |
M | Brass cage |
Sizes
The most common ball bearings are:
Abbrev. | Inner D. | Outer D. | Thickness | Notes |
---|---|---|---|---|
608 | 8 mm | 22 mm | 7 mm | A common roller skate bearing used extensively in RepRaps. |
626 | 6 mm | 19 mm | 6 mm | |
625 | 5 mm | 16 mm | 5 mm | |
624 | 4 mm | 13 mm | 5 mm | |
623 | 3 mm | 10 mm | 4 mm | |
603 | 3 mm | 9 mm | 5 mm |
The 608 size ball bearings in particular are extremely low cost. Their 8 mm bore size almost forces us to mount them on:
- M8 threaded rod or M8 bolt, as in the Mendel Z-axis; or
- 5/16 inch bolts or 5/16 inch threaded rod, as in the SAE Prusa Mendel; or
- something like a plastic bearing clip 01 (still experimental).
The 626 size ball bearing have a 6 mm bore size. We can mount them on:
- M6 bolts and M6 threaded bar, as in the RepRapPro Huxley frame assembly.
The 624 bearing have a 4 mm bore size. We can mount them on:
- M4 bolts, as in the Mendel X-axis; or
- #8 bolts (4.1656 mm) with a little tweaking, as in the SAE Mendel.
The 626 and 624 bearings seem to cost more than 608 bearings, but M6 and M4 bolts and threaded bar cost less than M8 threaded bar and bolts, so it's almost a wash.
Vendors
Vendor | From | 8 mm | 6 mm | 5mm | 4 mm | 3 mm | Additional notes | |
---|---|---|---|---|---|---|---|---|
Charlie's 3D Technologies | BE | 608ZZ | ||||||
RobotDigg | CN | 608ZZ | 626ZZ | 625ZZ 625-2RS |
624ZZ | 623ZZ | ||
Paoparts | FR | 608ZZ | 626ZZ | 624ZZ | 623ZZ 603ZZ |
|||
Reprapsource | DE | 608ZZ | 624ZZ | |||||
RepRap Kits | UK | 608ZZ | 624ZZ | |||||
3DMakerWorld | US | 608ZZ | ||||||
BOCA Bearings | US | many | many | many | many | |||
VXB Ball Bearings | US | many | many | many | many | |||
D&D-TOP Bearings | CN | many | many | many | many | |||
Technobots | UK | 608ZZ more |
626ZZ more |
624ZZ more |
623ZZ 633ZZ more |
|||
CIE Auto Source | CN | many | many | many | many | |||
Wholesale Skateboard Bearings | US | 608SS | Minimum 80 pcs. | |||||
Imprimante 3D France | FR | 608ZZ 608ZZ (10 pcs) |
626ZZ 626ZZ (10 pcs) |
624ZZ 624ZZ (10 pcs) |
623ZZ | Paris area. MR105ZZ (5 / 10 / 4) | ||
chartup.com System Engineering GmbH | DE | 533Z |