I apologize for asking something that I am sure has been discussed, but I tried a few searches and couldn't find it.
I'm considering how to configure the bearings for a belt grinder I am building. One approach is to press each outer race in to the wheel from each end, capturing an inner-race spacer between the bearings, so that tightening a bolt through them cannot apply too much axial load to the bearings. That approach would require that the spacer have an accurate length relative to the distance between the outer-race-pocket shoulders, as the difference between those lengths controls axial preload on the bearing pair.
In such an arrangement, I imagine I will cut the outer-race pockets and measure (as well as I can) the distance between them, then cut tube for the inner-race spacer to achieve the preload I want (probably as close to zero as I can get, to avoid overloading the bearings). The bearings are 10mm bore, C3 clearance, so basically 0.0003-0.0009" radial clearance before any press fit on the outer race.
Any thoughts on how to best cut the tube to length? It will be aluminum that I drill/bore for ID clearance, and I can face off one end then part off. But to accurately cut the length, I was thinking about mounting vertical in the mill and trimming the top off. I don't have DROs so can't part off accurately; I think the carriage travel I would need is longer than my dial indicator.
If there is a better way to mount the bearings, I will consider it. As the axial loads are small and I don't really need any preload, it may be better to simply cut spacers for the ID, have a sliding fit for one outer race, and a retaining ring plus shoulder for the other outer race. That way all the axial load would be carried by one bearing, but the system would be insensitive to temperature and to the length of the parts. I may have just talked myself into that... But I would still appreciate any input on the cutting-to-length question above.
I'm considering how to configure the bearings for a belt grinder I am building. One approach is to press each outer race in to the wheel from each end, capturing an inner-race spacer between the bearings, so that tightening a bolt through them cannot apply too much axial load to the bearings. That approach would require that the spacer have an accurate length relative to the distance between the outer-race-pocket shoulders, as the difference between those lengths controls axial preload on the bearing pair.
In such an arrangement, I imagine I will cut the outer-race pockets and measure (as well as I can) the distance between them, then cut tube for the inner-race spacer to achieve the preload I want (probably as close to zero as I can get, to avoid overloading the bearings). The bearings are 10mm bore, C3 clearance, so basically 0.0003-0.0009" radial clearance before any press fit on the outer race.
Any thoughts on how to best cut the tube to length? It will be aluminum that I drill/bore for ID clearance, and I can face off one end then part off. But to accurately cut the length, I was thinking about mounting vertical in the mill and trimming the top off. I don't have DROs so can't part off accurately; I think the carriage travel I would need is longer than my dial indicator.
If there is a better way to mount the bearings, I will consider it. As the axial loads are small and I don't really need any preload, it may be better to simply cut spacers for the ID, have a sliding fit for one outer race, and a retaining ring plus shoulder for the other outer race. That way all the axial load would be carried by one bearing, but the system would be insensitive to temperature and to the length of the parts. I may have just talked myself into that... But I would still appreciate any input on the cutting-to-length question above.
