Many years ago, Pontiac had a similar problem with a long slender driveshaft(something like a diameter less than an inch). If I remember correctly, the transmission was near the differential, so the shaft ran at engine speed. They solved the vibration by deliberately placing a bearing in the middle of the shaft that was out of alignment with respect to the bearings at both ends.
I spent some time looking for a supplier that sold bearings that were specifically marked as precision type, the link you gave seemed to suggest that all ball bearings were precision made, wich is kind of true.
however I read about SKF 'explorer' bearings and thought they seemed pretty good, then later while I was looking in my box of bits I saw some of the bearings I had were marked skf explorer, I remember they were quite a bit more expensive, but at the time i thought id see if they were any better, they were just listed the same as all the other bearings.
the old bearings had been through quite a bit and had probably got somewhat dirty anyway, however these new ones are stil just deep groove ball types and still have a considerable amount of play when loose. I looked more for four point contact bearings, but seems to be they are made very large for turntables >>25mm, or very small
The internal clearance (what you're describing as "play") is controlled independently of the precision in deep groove bearings. If you look at the complete part number for a specific bearing it will include a C followed by a digit, which signifies the internal clearance. Unless you specify otherwise, the internal clearance in an ABEC7 bearing won't be much different than an ABEC1.
I don't believe all mfrs use exactly the same C codes, but IIRC SKF uses C0 to specify a bearing with minimal clearance and C3 for standard clearance.
Wel I dont quite need 40hp, in fact im using about 10 watts, half of wich is probably wasted in the winding resistance, and theres a fair amount of wind from the motor too, the optical devices dont seem to cuase much wind at all.
I suppose I could use the thing in reverse, blowing air into it so I wouldnt need a motor. my optical devices have 6mm and 2mm dia bore holes in them. and need to be 1meter apart, so I'd need little shafts coming out of the end.
In fact if I was using air to drive it I would consider using air bearings. a compressor might be a bit noisy to leave running overnight in the garage.
although my lashed up prototype is running pretty sweatly upto12krpm atm, I just have to wait a while to see how the errors average out.
There was one bearing in the motor I couldnt replace without some serious surgery. the rest are new, and I think the only noise is coming from the one.
I might toy with some designs for some electromagnetic bearings while im waiting, maybe combine the motor stator windings with it.
oh and im also designing some way to balance it more easily, probably using stroboscope, inductive proximity sensor, and some pairs of slightly eccentric rings on the shaft.
All prop shafts on rear wheel drive cars with stick run at engine speed in top. Faster than the engine in overdrive.
Which reminds me: there was a WWII warplane with a quill shaft under the pilot's seat, connecting the prop and the engine. This had a curved drive line too.
The talk of ABEC 7 bearings reminds me that I bought a little gal a pair of roller skate boots at Christmas.
She wanted a special wheel color on the buckskin boots, and the upgrade came with premium wheel bearings too - ABEC7 if I recall. The bearings are about the size the questioner is using.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.