To be fussy about it, you're more likely to measure roundness than concentricity, and more likely to measure deviation of diameter than roundness, which is not exactly the same thing.
[Sorry about that, but I wrote an article about it once. d8-)]
You are worrying me. ;)
I wondered about that. Seems like the precision bearings in my toolpost grinder, probably ABEC-7, are rather stiff.
Speed and load will be low in an anenomometer, so precision really isn't necessary. I'll probably use small motor bearings or router guide bearings.
In the 50's, when "made in Japan" was worse than "made in China" is today, there was a town named "Usa" in Japan so they could mark stuff "made in usa". Or so it was reported in the Reader's Digest.
The internal clearance on deep groove bearings is specified independently of the the precision class. As far as I know, the standard clearance is more or less the same across all classes.
Lubricant _is_ a very big factor if the goal is to minimize friction at low loads. I kludged a simple test rig to measure bearing drag for a project that required very low drag at high speeds. It consisted of a piece of fine spring wire held in the Bridgeport spindle which drove the outer race of the bearing. A strobe illuminated a circular paper scale graduated to indicate the deflection of the spring with the spindle turning. It was easy to see the effect of lubicant viscosity with this setup.
I thought I had a photo, but all I can find is the final product.
ABEC classes never apply to tapered roller bearings - they use an entirely different system.
Do real anemometers have ball bearings? I'm thinking my cheapy weather station has bushings.
Wes
100% marketing. So silly, there is a wheel mfg. called ABEC 11.
I use this guys bearings:
When my wheels are still spinning after popping out of the pool 3 minutes later, groms always come up and ask the ABEC rating of my bearings. Silly kids.
Check me out:
I would use Teflon or jewel bearings. I think that any ball bearings would have more low speed drag especially if they have seals. A stainless shaft and either a glass jewel or teflon would not need protection from the elements.
Dan
When were the ABEC spec's first published? I would guess today just about any new machine used to make ball bearing is 1000X better than is was back then. A manufacturer would have to screw up bad to make an ABEC 1 today, IMHO.
Thank You, Randy
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how about a link we don't need to log into.
Thank You, Randy
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Not really - up through a 50 mm bore there is only 1 to 2 micron difference in the allowable bore tolerance between each grade. For example, a 50 mm bore ABEC -1 has a tolerance range of 0 to -12 microns whereas an ABEC-3 is 0 to -10 and an ABEC -5 is 0 to -8. If a manufacturer allows their tolerances to float across the range there is little difference between the ABEC grades. Since most try to stay in the middle of the range then drifting off 4 - 5 mm would be substantial though.
That makes sense. Most high-precision bearings are paired, such as for the top and bottom of a machine tool spindle.
Right, seals are colored (they're rubber) Shields are metal, and aren't colored. I always get them confused...
Oops! Sorry. Try these:
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