Bearing
A bearing ensures two parts can slide or roll along eachother with minimal friction.
Ball Bearings
Cheap and widely available
The first digit refer to the kind of bearing, the second its robustness, the third usually for the bore size. Then ZZ = double shielded ; 2RS = double sealed ; etc.
If we were generating a lot of dust and grit -- perhaps with a Milling and Drilling Head -- we would want two rubber seals ("2RS") to keep the dust and grit out. But most RepRaps are *not* generating a lot of dust and grit, so we usually prefer metal shields ("ZZ") or unshielded (??) in order to make it easier to add a little lubrication oil.
Learn more here : http://www.gizmology.net/bearings.htm
For the most common size :
- 623 = 3 x 10 x 4mm (ID-OD-thick)
- 624 = 4 x 13 x 5mm
- 626 = 6 x 19 x 6mm
- 608 = 8 x 22 x 7mm
| Supplier | From | Model | Approximate Cost | Additional notes |
|---|---|---|---|---|
| Charlie's 3D Technologies | Belgium | 608zz | 0,61 € | - |
| Paoparts | France | 623zz, 624zz, 626zz, 608zz | 0,69 - 1,20 € | - |
| Reprapsource | Germany | 624zz, 608zz | 0,69 - 0,79 € | - |
| Reprapkit | UK | 624zz, 608zz, 6810zz | 0,85 - 0,95 £ | - |
| 3D Maker World | US | 608zz | $0.75 ea | - |
| Bocabearings | US | many | - | - |
| VXB | US | many | - | - |
| DDB-Tech | China | many | - | - |
| Technobots | Uk | many | - | - |
| CIE Auto Source | China | many | - | - |
| wholesale skateboard | US | 608ss | $ 0.38-0.50 ea | minimum 80 pcs |
| imprimante3DFrance | France | 608ZZ, 623ZZ, 624ZZ, 626ZZ | - | Paris area |
The "608" size ball bearings in particular are extremely low cost. Their 8 mm bore size almost forces us to mount them on:
- 5/16 inch bolts or 5/16 inch threaded rod, as in the SAE Prusa Mendel; or
- M8 threaded rod or M8 bolt, as in the Mendel Z-axis; 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).
Linear Ball Bearings
See: Linear bearing
Bushing
Less noisy than linear ball bearing but not always practical to integrate
DIY PLA bushings
DIY UHMWPE linear bearings (ultra high molecular weight polyethylene) are self-lubricating, so rails can stay clean and dry.
| Supplier | From | Size | Material | Approximate Cost | Additional notes |
|---|---|---|---|---|---|
| Goldmine | US | 8 mm | bronze | 1 $ | don't use on 5/16" rod |
| iglidur D6 Paoparts | France | 6 mm | plastic | 1,20 € | - |
| iglidur D8 Paoparts | France | 8 x 9 x 12 mm | plastic | 1,50 € | - |
| Everything Igus | multiple | - | - | - | |
| Sdp-Si | US | 8 mm | plastic | 1,80 $ | self-aligning |
| Spyraflow | US | 8 mm | bronze | ? | self-aligning |
| Techpaladin | US | 8 mm | bronze | 1,70 $ | self-aligning |
Linear Rail
- Igus
- schneeberger.com
- pbclinear.com (also for many linear bearings)
- Hiwin (look on ebay)
