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.
Ball bearings are usually closed and have their own lubrication, so no additional lubrication is needed.
There are several types of ball bearings:
|ZZ||Shielded, double||Sufficient for most RepRaps.|
|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|
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|
|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.
|Vendor||From||8 mm||6 mm||4 mm||3 mm||Additional notes|
|Charlie's 3D Technologies||BE||608ZZ|
|VXB Ball Bearings||US||many||many||many||many|
|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 (10 pcs)
624ZZ (10 pcs)