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tapered roller bearings

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  • 754
    replied
    Did you try Ebay ? When people buy out suppliers, factories, shop , they sell the bearing stocks off. They may ask a fairly high price , or be quite reasonable. But at the end of the day, many will sell for whatever they can get for them..
    Precision is a relative term.... the process to make bearings is all precision work. So when you offer tapered rollers, rather than bushings... it's easy to say precision bearings. They are generally easy to adjust , a big plus.
    Last edited by 754; 03-13-2021, 03:16 PM.

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  • johansen
    replied
    If you were to take the rollers out and lap the face of the big ones, you could reduce the rolling element contribution to the bearings runout.

    measuring them would be difficult.

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  • darryl
    replied
    I built a spindle once using tapered roller wheel bearings. I had no problem with runout, easily less than a thou. Somebody mentioned .005 could be acceptable- now that is going back to the Flintstones. Considering how easily modern machining methods can be within a couple tenths, I would be appalled at that much runout, even for a Chinese bearing.

    I think you could be well advised to order in a small quantity of regular bearings, and test them. Chances are that less than one out of ten would be rejects due to runout. Correct me if I'm wrong- but I'm thinking that if you can machine something to say half a thou, that will cover virtually everything you'd be doing. If these are going into a 'precision' lathe- say a toolroom lathe- then perhaps that's another thing.

    Just my 02

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  • Sparky_NY
    replied
    It hasn't been mentioned yet but precision class 5 and 7 bearings also require very specific shaft and housing tolerances for their operation. Without the specified shaft/housing fits a higher class bearing is a waste and may not last as long as a standard bearing. Shaft/housing fits play into obtaining the proper internal clearances and preloads. Also, to get extremely low runouts with precision bearings its standard practice to also grind the internal spindle taper using the precision bearings in place.

    All I am saying is that there are a lot more factors at play in a precision spindle than just the bearing precision.

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  • dian
    replied
    so what size and what precision do you need?

    if your talking about timken then "standart" is N/2/P6. "0" is B/P4 with about 4µ total runout depending on size. do you need better?
    Last edited by dian; 03-12-2021, 05:52 AM.

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  • JRouche
    replied
    Originally posted by MattiJ View Post

    As an example older Weiler (highly regarded German lathe brand) was calling for precision spindle bearings. After digging some old references it turns out that the designation is same as ABEC-5 today.
    All SKF ball bearings have been manufactured to ABEC-5 runout for something like last 30 years so sourcing replacement was rather easy.
    ABC-LMNOP?

    The bearing nomenclature has been decimated with all the fabled imports.

    I think, I could go see but the simple bridgeports from way back called out class 5 then 7. Why? Dunno. Just what the book says. I didnt write it.

    Skateboarders with their class 9 lol JR

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  • old mart
    replied
    In the UK, a recommended bearing supplier is "Simply Bearings".

    https://simplybearings.co.uk/shop/Be.../c3/index.html

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  • JRouche
    replied
    Originally posted by henryr View Post
    I’ve spent hours over the last three days looking for tapered roller bearings with tighter than normal tolerances and didn’t find any. Timken and SKF


    For new bearings I would not stray far from them.



    Thanks,
    henryr
    ACB. Figure it out. JR

    Ooops.. P.S.> They are called Angular Contact Bearings....

    Last edited by JRouche; 03-11-2021, 02:04 AM.

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  • Ringo
    replied
    I recently put new bearings in my Millrite, it called for higher class bearings and I found them. Timken had them listed, and of course the price goes up by cubic dollars every step class.

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  • MattiJ
    replied
    Originally posted by Sparky_NY View Post

    Yes but precision grade tapered roller bearings are e extremely rare breed as the OP is finding out. My bet is that people are assuming they are precision grades when in fact they are standard ones. Its worth noting that with modern cnc equipment precision tolerances/fits/finishes have gotten pretty routine, a common grade bearing today may well be as precise as a precision of yesterday. Look at Old Mart's post, .0001 TIR with standard bearings.
    As an example older Weiler (highly regarded German lathe brand) was calling for precision spindle bearings. After digging some old references it turns out that the designation is same as ABEC-5 today.
    All SKF ball bearings have been manufactured to ABEC-5 runout for something like last 30 years so sourcing replacement was rather easy.

    Leave a comment:


  • old mart
    replied
    You would expect good results with high quality bearings, the big names have very good inspection standards. Buy from a proper bearing stockist for peace of mind. I would have found 0.005" tir to be acceptable for the mill spindle. That lower half of the spindle is a spare for one of the Seig Chinese mills, and I was very pleased to find that the bore and od had no measurable eccentricity.
    Last edited by old mart; 03-10-2021, 04:10 PM.

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  • Sparky_NY
    replied
    Originally posted by chipmaker4130 View Post

    Sometimes the only mark on a precision tapered roller brg is a tiny dot on the edge of the race.
    Yes but precision grade tapered roller bearings are e extremely rare breed as the OP is finding out. My bet is that people are assuming they are precision grades when in fact they are standard ones. Its worth noting that with modern cnc equipment precision tolerances/fits/finishes have gotten pretty routine, a common grade bearing today may well be as precise as a precision of yesterday. Look at Old Mart's post, .0001 TIR with standard bearings.

    Leave a comment:


  • chipmaker4130
    replied
    Originally posted by Sparky_NY View Post
    . . .there were no markings on the bearings to signify a precision grade. . .
    Sometimes the only mark on a precision tapered roller brg is a tiny dot on the edge of the race.

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  • old mart
    replied
    I fitted SKF to the lower and Timken to the upper spindle positions of the R8 modification for the Tom Senior light vertical. They are just standard off the shelf and the spindle runs 0.0001"tir which is good enough for me. Actually, I was very pleased. The top bearing runs on the splined half. Click image for larger version

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  • David Powell
    replied
    The tapered roller bearings fitted to Atlas milling machines are also used in Fiat 500 car back axlesof the 1950s. Regards David Powell,

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