Reamer size questions

Bit of a mixture here as a H7 reamer comes from the metric hole based system where the hole is -0 / + a bit so the shaft is normally over but we can work back. Imperial was typically shaft based hence the over and uner reamers the USA has

So shaft 0.250 +/- 0.0002 = 0.2502 /0.2498 which converts to metric of 6.345 / 6.355

If we look at class of fit H7/p6 (Locational interferance) the tolerance is between +0.000 / -0.020

See here 3/4 way down for description of fits Fit Types

See here 3rd table down Fit Table

so our hole should be between 6.345 and 6.333

so we need a 6.333 reamer H7 which should give 6.333 -6.345

Hope you can follow the logic

Steve

Quote 'so we need a 6.333 reamer H7 which should give 6.333 -6.345', you surely are not suggesting that such a thing actually exists? I think the OP is more than a little confused at this stage with all the suggestions coming his way.

Tony

Tony, go back to the first page where I suggested a 6.33mm reamer and linked to a supplier who has several options such as hand, chucking, stub etc. and also read the other posts were suppliers of reamers in 0.01mm steps have been suggested. Not seen them available in 0.001mm increments though.

Jason, of course 6.33[in H7 & H6?] reamers exist, but the suggestion of a 6.333 will totally confuse the OP.

Tony

I set out to show the working of how to get to a calculated size so that if a transition fit or greater interference was required it could be worked out. the links should go to the appropriate tables.

Its a fact that limits and fits are designed at the .001mm level even if some rounding is dome from 6.333 to 6.33.

Jason was spot on with the size but the question was repeated about the amount of interference required, example given,

Steve

I can only repeat the numbers given by Steve above, 6.33 mm for a drive fit for a 6.35 (1/4" ) shaft.

Kind regards,
Hans

Edited By Versaboss on 03/12/2019 14:39:47

Ok everyone thanks a lot for your input. I think all this has given me a better understanding on the matter!