tapered roller bearings

[WindyParticipant @windy30762]

On my use of bearings I always buy well known brands.

Found cheaper bearings can leave a lot to be desired

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Henry Rancourt on 12/03/2021 15:19:49:

I emailed many distributors, in the US, UK and Japan and Timken, SKF and Nachi technical support, and all told me they only make tapered roller bearings in the lowest tolerance class like 0 or K. It seems there is one company, Gamet, that makes them but cost is around $1000 for one bearing. So i'm considering using angular contact or deep groove ball bearings. My research has started.

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Yesterday you wrote that ^^^

….and now you write this:

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Posted by Henry Rancourt on 13/03/2021 01:09:53:

Since I have to replace the bearings I think angular contact bearings with tighter tolerances make sense. They don't cost much more than top quality tapered roller bearings.

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Sorry, Henry … I appear to have lost the plot !

MichaelG.

[DiogenesIIParticipant @diogenesii]

Posted by Henry Rancourt on 13/03/2021 01:09:53:

Since I have to replace the bearings I think angular contact bearings with tighter tolerances make sense. They don't cost much more than top quality tapered roller bearings….

Do bear in mind that the original taper-roller fitment might have been deliberately chosen in order to meet some specific requirement – controlling whip in the end-driven spindle, as an example…

[Ketan SwaliParticipant @ketanswali79440]

Posted by Henry Rancourt on 12/03/2021 15:19:49:

I emailed many distributors, in the US, UK and Japan and Timken, SKF and Nachi technical support, and all told me they only make tapered roller bearings in the lowest tolerance class like 0 or K. It seems there is one company, Gamet, that makes them but cost is around $1000 for one bearing. So i'm considering using angular contact or deep groove ball bearings. My research has started.

Hi Henry,

If your Prazi SD300 uses tapered roller bearing (TRB) for the spindle, you should use TRB as a replacement. As mentioned before by Hopper, most modern general purpose TRBs made by the likes of Koyo/Nachi for example will be fine for your purpose.

Note the following, which you may wish to consider:

• the inner and out rings of TRBs are offset, making the overall width of the bearing wider than angular contact bearing (ACB) and deep groove ball bearing (BB)
• if the existing bearing is a TRB, it will sit in a particular way on the spindle and/or shoulder of the head casting. replacing with a ACB or BB will mean introduction or removal of spacers to take up the difference in space on the spindle.
• TRBs are made up of rollers which make full contact with the inner surface of the inner/outer ring. ACBs and BBs have balls which do not have full contact with most of the inner surface of the rings. As a result, TRBs offer the highest accuracy, lowest speed after pre-load. ACBs allow pre-load with marginally lower accuracy than TRBs, but allowing higher speeds than TRBs after pre-load. BBs are not really made to deal too much with pre-load, but provide the most speed with lower accuracy. Speed in not really relevant for your lathe.
• You may have seen super precision ACBs with light, Medium or Heavy pre-load, which will be a lot more expensive than general purpose TRBs. However, such ACBs are designed for use in high speed spindles usually running at around 10,000 rpm+, and of very little use for your purpose.

Ketan at ARC

[duncan webster 1Participant @duncanwebster1]

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I've had this for many years, cant even remember where I got it from. Little bit of surface staining but not on races. If it's any use it's yours for the cost of postage, send me a pm

[Author]

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