Bearing on a shaft
###Bearing on a shaft AnAn 8 mm (ID, Internal Diameter) bearing should always fit on an 8 mm (OD, Outer Diameter) shaft. If it does not fit, one of the 2 is of a different size. Please use a caliper to determine the size of both.
Bearing in a housing
###Bearing in a housing IfIf it is the outer size of the bearing, i.e. fitting in a printed carriage or a bearing housing (e.g. SCxxUU), you should be aware of the different sizes of polymer bearings. E.g. there are RJMP-01-xx and RJ4JP-01-xx types of polymer bearings (xx denotes the shaft diameter, e.g. 08 for 8 mm shafts).
For RJMP-01-xx bearings (not compatible with LMxxUU bearings):
// Parameters for RJMP-01-xx (shaft size xx, all dimensions in [mm]) // Designation d1 d2 B B1 s dn //------------------------------------------- // RJMP-01-08 8 16 25 16.2 1.1 15.2
For RJ4JP-01-xx bearings (compatible with LMxxUU bearings):
// Parameters for RJ4JP-01-xx (shaft size xx, all dimensions in [mm]) // Designation d1 d2 B B1 s dn //------------------------------------------- // RJ4JP-01-08 8 15 24 17.5 1.1 14.3
d1 is the inner diameter, d2 the outer diameter and B the length of the bearing
The RJ4JP-01-08 bearings are drop-in replacements for the LM8UU linear bearings. Note that the RJMP-01-08 have a larger outer diameter and do not fit into the regular bearing housings. The increased thickness gives the bearings more rigidity.