Spindle Bearings....
Reply with Quote
Re: Spindle Bearings....
Greetings,
Let's start here... do not change the contact angle on your bearings. Contact angles are very specific to the need at hand. Just replace with what exactly is in there. Even though I know a couple things about super precision bearings, neither of us knows enough about spindle design and engineering to change something as drastic as that. You don't mention what the spindle is out of or its top speed, but if you must get fancy, consider some manufactures "robust" series or ceramics. I think many basic designs can be had with a higher ball compliment, which may be stiffer, but may have other trade offs like noise and heat generation. Consult the manufacturer's literature concerning their alternate systems. If your bearings are greased, and you're trying to do something out of the ordinary, get them pre-greased, and/or pregreased and sealed. Handling and contamination from dirt of a hundred varieties is your greatest enemy in a spindle rebuild. Also check the squareness and condition of your precision lock nuts and that spacer you speak of. And any other clamp ring or spacer you may have. You'll typically have an outer race clamping flange on the nose end of your spindle. If anything, you may have to grind or machine to suit to get the clamping interference that is needed, because every set of bearings is going to have a different total thickness. There are another hundred and one things to know about what you're up to, but there are tons of great guides and manuals put out by the major bearing manufactureres to help you there. Consider getting a bearing heater too. Hammering is not allowed and slip fitting with heat is slicker than press fitting. Forget about selective fitting, which you'll read about. That's only for OEMs. I've yet to find a bearing supplier that will allow me into their back room to pick mine out of a batch. Many won't have a batch to pick from anyway. Hundred to one you'll end up with a "universal ground" bearing. Singular bearings ground to be used in any configuration and with any other of the same suit. The most you can do is try to match up the inner and outer ring diameter and width tolerances that are listed on the package. And use the markers on the bearing rings that list their points of greatest deviation. Many people don't have the measuring equipment of enough sensitivity to even find the small deviations in their shafts and housings. In that case, it's best not to line up all the ring markings, but differ them around the circumference evenly. Less likely to compound a problem that may or may not exist.
Just noticed some specifics in your original request. The clearence (guessing the C8) and preload are all built into the part number, so nothing to worry about there. Mostly when installing bearings with a taperd sleeve do you have to concern yourself with clearance/preoad. Correct me if you must but I don't think that's what you've got. One last word... clean your work area best you can before starting, and make sure you have the fitting and mounting tools at hand.
Finally. No really. From what I read, there is a big problem with counterfeit super precision bearings in the world market today. If you see some on ebay per say for a 5th of what you can buy them from a local reputable supplier, be afraid, because fewer statements are truer than, "you get what you pay for." Just sayin.
Originally Posted by the_gentlegiant
