Shaper: play between arbor and cutter head

[brent stanley]

I worked up the attached table to summarize some of the info in this thread. As others have pointed out the ISO tolerance system uses capital letters to specify hole or bore tolerances and small ones to specify shaft sizes both based on the nominal size. The H tolerance is very common and indicates that the hole will be as a minimum the nominal size plus some amount a machining tolerance indicated by the associated number. The small letter say g specifies that the shaft (arbor) will as a maximum be the nominal size minus some amount and as a minimum be the nominal minus some larger amount to provide machining tolerance. I have a new shaper with an 1-1/4 arbor which measures 1.2494. No tooling as yet but the arbor spacers measure 1.2501. Both measurements are within the H7 g6 specification which is a common one. Measuring to tenths is tricky so I may be off by a tenth or so.

Thanks Robert, that was my understanding too. That 30mm change point is inconvenient for shaper users! I have spindles made to the larger end of the range but I always supply new tooling to use as a test piece for the machinist so it may be snugger, but it will always go on, won't stick if the shaft warms up and is a bit more accurate. It can help with multi component/stacked tooling for keeping their bits lined up properly with respect to each other, but is less forgiving to getting dinged up if you're clumsy with the wrench!

[Greg Quenneville]

…Up here in Ontario it's around $350 for a one-off spindle.

Wow that’s cheap. The machine shops around here would be 3 x that much. In USD too.

[brent stanley]

Wow that’s cheap. The machine shops around here would be 3 x that much. In USD too.

. I bet that number is from 3 years ago now though!