Curtis, My apologies for this late response to post #6, I had a lightening strike and was knocked out of commission while typing the response.P'd me off.
While reading your post I noticed this "max rpm 47k spec" in SKF precision bearing description.
I have a copy of the "SKF HIGH-PRECISION BEARINGS". In their tech section under "Speed Ratings" to paraphrase;
Valid provided the bearings are lightly preloaded,by means of springs [lathe spindles are normally heavily loaded by means of positive clamping]
Transport heat away from bearings is good. [Difficult without external air or liquid cooling]
When single bearings are adjusted against each other or matched sets are to be used, the speed values must be reduced. [pair of preloaded angular contact bearings]
The higher the contact angle, the greater the axial capacity & lower the speed. The lower the contact angle the greater the radial capacity & speed.
In short, the general bearing requirements for a lathe spindle tend to reduce the max. speed capacity of the bearings. The opposite is true for a high speed engraving spindles.
In reference to your bearing arrangement I'd recommend a pair of back to back medium/heavy preloaded, 25 degree contact angle bearings at the chuck end positively secured to both the spindle shaft and the housing. The rear bearing, a radial bearing secured to the spindle shaft and allowed to "float" axially to compensate for spindle length growth due to heat expansion.
If you intend to operate over 10k rpm, you'll likely need an air/oil mist lube system to avoid overheating. Even a recirculating oil system can get hot at elevated rev's.
Is the 2.3" dia. you mentioned the ID of your bearings? 55 mm? 60 mm?
Dick Z
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