Drawing shaft diameter 8h7 (metric) ???

[Argofanatic]

Can someone shed some light on this for me. I've never seen this notation before. A shaft with diameter 8h7 (metric)? Is this 8.7 mm ?

Thanks,
Marc.

[HuFlungDung]

h7 is a certain tolerance class. If you can find a chart somewhere, it will give you the min/max for that fit. I have seen a chart like that in the front of my FAG bearing catalogue, but I have not memorized the list

[Argofanatic]

Thanks, that would make sense.
So the diameter would be nominal 8mm.

[jerber]

Over here we use that kind of notation a lot.

8h7 means 8.000 to 8.015 mm.

[JH-Q]

"8h7 means 8.000 to 8.015 mm."

As for hole, it would be so, as for a shaft it is undersize.
The idea for these tolerance classes are to achieve a certain fit with different diameters.

[RICHARD ZASTROW]

My belief is 8h7refers to a shaft 8.000/7.985 mm.
A hole would be 8H7, 8.015/8.000 mm. But then I was brought up on inches.
note: Machinery's Handbook Allowances & Tolerances

[DareBee]

Richard is correct.

lower case letters denote shaft sizing and upper case denote hole sizing.
These tolerances are diameter specific; a 20 h7 is different than an 8 h7.

FYI an H7 is a normal tolerance for a REAMED HOLE.
I would normally put a j5 or j6 shaft in this hole.

This information is all available in your Machinerys Handbook. Look up ANSI limits and fits.

This is actually a VERY good system IMO, I would like if it was used more widely.

I got familier with it working from German FAG prints.

[fpworks]

I have this chart printed out and pinned above my desk:

http://www.misumiusa.com/CategoryIma...C1835-1836.pdf