Strip sander idler wheel bearings

[jabuzzard]

I took the metal idler wheels off and removed the central bearings so I could dunk them in some evaporust as they were badly rusted. Once I was sensible and drilled a hole in a block of wood so the they didn't fall over it was easy enough to remove the circlip. Then a poor man's arbour press (aka a bolt and socket) and the bearing came out easy enough. They came up ok if somewhat pitted but I doubt that will affect their performance. Anyway, the removed bearings don't feel very smooth. The application of the poor man's arbour press again and the central bushing came out easy enough.

The issue is that the bearings are marked 6203 RSR, no problem I can find them online easily enough. However, every reference I find suggests this is a metric bearing with 40mm outer diameter 17mm diameter bore and 12mm thick with rubber seals on both sides though 2RS seems to be a more common marking these days. Application of the callipers suggests this is indeed 40x17x12mm but it feels somewhat weird that an America made device this old would be using anything in metric. Nothing else I have ever seen on a Shopsmith is metric. I mean even the idler wheel seems to be an Imperial dimension part, apart from the bore for the bearing, and the outer diameter of the bushing which randomly goes from 17mm to ⅝" for the bit not in the bearing. That must have been fun machining as all I can say.

Does anyone know if this is really a metric bearing or is it that because I am in the UK I am being shown some equivalent item on the Google search and Shopsmith actually used some Imperial dimensioned bearing?

[edma194]

A lot of bearings are made in metric sizes only now. Sometimes a version is advertised with dimensions in inches, sometimes only the OD, but I've seen reports that they are no different than the metric sizes.

[JPG]

Even back in the Goldie days, metric bearings were common. Then the 5/8" variation was an unusual item.

So rest assured being metric is normal and is to be expected. Do be alert to the 5/8" exceptions(outer and thickness are metric, center bore is 0.625").