Double Bearings Or Quad Bearings?

[ballscrewed]

I have 4 double row angular contact bearings and would like to know what would be the best arangement for mounting. Should I use 2 bearings or all 4 on the spindle? The buisness end of the spindle will unsupported. I have room to mount all 4 bearings about mid way on the the spindle shaft and mabey 1 regular bearing at the drive end of the shaft for alittle extra suport. Two of the bearings have seals the other two do not. If you need more info on bearings or shaft let me know.
Aaron

[HuFlungDung]

How long is this spindle? 24 inches or 6 inches? It makes a difference as to where the midpoint is

If for some reason there is no way to improve this design, then put one pair of bearings in the middle and the other pair at the drive end. The further back from the business end that you put the bearings, the more load is transferred to the rear bearings. So to get the maximum stiffness of a poor design, that is what I would recommend.

[NC Cams]

You don't mention bearing sizes nor intended speeds nor desired life nor intended loads nor load conditions. With all due respect, you simply have NOT provided sufficient info to provide a SWAG let alone a properly formulated answer.

I'd suggest that you check out any bearing applications handbook for insight into what to do/how to analyze the loadings so as to properly apply/select the bearings. Try here for starters:

http://www.bardenbearings.com/literatr.htm

http://www.timken.com/products/bearings/catalogs/

http://www.jp.nsk.com/app01/en/catal...gi?ec=bearings

For example:

If you are putting the bearings at the ends of a shaft and the load is applied to the middle, that's one situation.

If you are making a machine tool spindle, and the cutter is cantilevered 6" out from the end where the bearings are mounted, that's another and entirely different scenario.

Ultimately, someone has to do the math to determine proper bearing locations and viability for any application. The posted websites should get you the info you need to do it and/or show you how to do it.

If you can't do the math, I'd suggest finding someone who can. You can also call the tech support dept for the maker of the bearings you have -surely, they could do the math BUT they'll be asking you for more specific technical informatin about your application.

If/when you call, have the info ready (see the handbooks). Otherwise, be prepared to get blown off....

[martinw]

Dear NC Cams,

Thank-you for suggesting the NSK website

http://www.jp.nsk.com/app01/en/catal...gi?ec=bearings


Their download "Rolling Bearings" E1102 is simply fantastic but it does look a bit daunting at first.

Best wishes

Martin

[NC Cams]

Martin

You're welcome. Glad to have helped.

Please feel free to pass it on. Besides, i'm sort of getting tired of being the bearing clearance/fit guru.

Seems there are others on the site who don't find my way of "educating folks" to be as kind or beneficial as you did:

See post #7 in this thread:

http://www.cnczone.com/forums/showth...338#post155338

Some folks only want the answers (even if they don't know how to ask a question), not the how or where to find them.

[martinw]

Dear NC Cams

The links in post #7 mentioned above cover a lot of ground!

Best wishes

Martin