Ball bearing sizes/tolerances

[Davek0974]

Anyone know if ball bearings are made on-size and the fit is in the housing or vice-versa??

I have a 6208 bearing showing as 40mm id 80mm od and wish to use it as a calibration ring for a probe on my mill

I guess its not hypercritical as i don't work for aerospace but just interested

[boslab]

I often use bearings as ring gauges these days, a set of slips with 2 long cover slips is preferable if available, but you use what you have I guess.
Tidy skf are pretty accurate on ID, be warned there are some fakes! May not be so accurate.
Mark

[Mcgyver]

The fit is in the shaft and housing and the bearings are made within tolerance around the nominal size. Pretty darn good tolerances mind you. It will depend on class and size, and of course if its from a legit manufacturer (unless you believe all those skate boarders are really rolling on ABEC 9's lol).

For a bit of morning misery, wade into a bearing catalogue, not fun but all the tolerances are listed

[Davek0974]

Thanks

[old mart]

I have a small collection of bearing housings up to 6" diameter, they are made with such tight tolerances that they come in useful for packing pieces for milling.

[JoeLee]

Anyone know if ball bearings are made on-size and the fit is in the housing or vice-versa??

I have a 6208 bearing showing as 40mm id 80mm od and wish to use it as a calibration ring for a probe on my mill

I guess its not hypercritical as i don't work for aerospace but just interested

If you have a set of plus and minus gage pins you can find out. The pins are usually .0002 under on the minus pins and .0002 over on the plus pins.
I think the class Z ones are now .0001 under. You can also measure a shaft that one of your bearings is supposed to fit and figure it from there.

JL................

[JoeLee]

I have a small collection of bearing housings up to 6" diameter, they are made with such tight tolerances that they come in useful for packing pieces for milling.

What do you mean by packing pieces for milling??? I have an idea, but I'll wait to hear it from you.

JL..................

[Davek0974]

If you have a set of plus and minus gage pins you can find out. The pins are usually .0002 under on the minus pins and .0002 over on the plus pins.
I think the class Z ones are now .0001 under. You can also measure a shaft that one of your bearings is supposed to fit and figure it from there.

JL................

Thanks - i don't have any gauge pins or slips yet, i have a feeling thebeariungs will be made to tolerances way beyond what i use

[CCWKen]

What do you mean by packing pieces for milling??? I have an idea, but I'll wait to hear it from you.

JL..................

I guess we'll have to wait for a translator. I don't know what "slips" mean either. I thought they were garments worn under women's dresses.

[Lew Hartswick]

I guess we'll have to wait for a translator. I don't know what "slips" mean either. I thought they were garments worn under women's dresses.

Obviously another "Old Timer" . :-) I havent heard that word in so many years I can't remember it. I wonder how many women even know what it was.
...lew...

[CCWKen]

Obviously another "Old Timer" . :-) I havent heard that word in so many years I can't remember it. I wonder how many women even know what it was.
...lew...

Oh yeah. When I was thrust (pushed) into the fashion conscience world, Nehru Jackets were coming onto the scene. Women were still wearing slips under evening dresses to hide panty lines, I guess. I told the wife not to wear panties. Problem solved.

[old mart]

Slip gauges are synonymous with gauge blocks. The bearing housings are the bits left over if you remove the rolling elements and cages. These rings have ground faces with very close tolerances which can be occasionally be useful to be used under a workpiece clamped to a mill table. As already mentioned, the inside and outside diameters are usually very accurately sized and useful for checking measuring instruments, at least to +-0.001". Sorry for the delay in explaining, I don't read every thread often enough.

[danlb]

And "Packing pieces" are put under a piece to elevate or level it? Like using 123 blocks or parallels?

I can see using bearing races as a very uniform base to hold a spherical object. It would also work as a single piece pair of parallels.

Dan

[old mart]

That's it exactly, danlb, the larger bearings were robbed from new helicopter gearbox bearings, we have loads at the museum. I hoard any precision ground bits, you never know when they might come in handy.

[JoeLee]

I would like to have one of those bearing races for tramming purposes for my mill if they are at least 6" in dia.

JL..............