Tolerance. For press fit

[Tony Wells]

Save yourself some grief. Mark the two spots where the rings will be, and reduce the diameter in front of them to -0.001 undersize. They will get a good, straight start on the sections where the press fit is. It should not be pressed on all the way to the final location.

 

[Fixnair]

You should use some molybdenum disulfide lubricant on the shaft prior to pressing. It will prevent galling should you ever need to remove it.
lots of good info here.

 

[benmychree]

You should use some molybdenum disulfide lubricant on the shaft prior to pressing. It will prevent galling should you ever need to remove it.
lots of good info here.

Us old timers used white lead for press fits; nothing better, if you can find some, As to press fits, yes, the rule of thumb is indeed .001 per inch of diameter. Using as much as .003 would be quite difficult to assemble without damage unless liberally heated, which would then likely be a shrink fit. Incidentally,
the allowance for shrink fits is the same as for press fits, but they have some three to five times the holding power as press fits; this is due to the irregularities in surface finish are essentially smeared off with the press fit; that texture sort of "keys" the parts together in the shrink fit.

 

[Falcon67]

I would also put a slight chamfer on the target side of the hole and the edge of the final bearing surface. I use a little electric coffee warmer to heat bearings for pressing when assembling a rear end for the hot rods, or for axle bearings. Helps a bunch. I tend to use a little moly bearing grease on bearings when pressing.