Boring a Bearing Race

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mcman56
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Boring a Bearing Race

Post by mcman56 »

I would like to bore out an existing ball bearing outer race to make a basic ring. ID is currently 60 mm and I'll need to go out to 72 mm. I have used carbide end mills to cut inner races of roller bearings before so am thinking this is doable with a carbide boring tool, However, I did not have to hold any tolerance.
Are there any recommendations on speeds/ feeds/ oils/ cutting tip shape? I can see how a very sharp tip may be better for cutting but prone to breaking. This would be on an Enco 13 x 40 lathe. I can center in a 4 jaw chuck before boring.
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GlennW
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Re: Boring a Bearing Race

Post by GlennW »

I have more questions than answers, but run the lathe at the highest spindle speed possible.
Glenn

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whateg0
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Re: Boring a Bearing Race

Post by whateg0 »

I can't imagine trying to hold a tolerance on that. If it was me, I would probably try to bore them grind. Interested to see how you manage it.
John Evans
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Re: Boring a Bearing Race

Post by John Evans »

A ceramic insert bar would work better with a better finish. My experience with carbide with bearing hard surfaces it's doable but finish with not be great. Ceramic is run dry and is VERY frail ,real easy to loose the edge. I turned down pre 48 Ford rear axle housing bearing surfaces underside to install a new wear surface. Pre 48 Ford's had a big straight roller bearing that used the axle housing as the inner race. The ceramic insert worked much better and with great finish. Also needed a half thou tolerance held for the press fit of the new sleeve.
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ernest_t
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Re: Boring a Bearing Race

Post by ernest_t »

I'll second the ceramic insert. You can find them cheap on eBay. Most any grade or shape will do. Just make a boring bar to fit the insert. Mild steel will do fine. Run the lathe at the highest rpm and medium or slow feed. The harder the work piece the better it will perform. It want make chips, but a glowing red birds nest that quickly turns blue.

I've turned OD hard items with the glowing red shooting up 2 feet like a guiser and falling back down blue. It cools so fast you can grab the red with your fingers and never feel the heat. It squashes up like a ball of cotton. Does not feel like metal.
mcman56
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Re: Boring a Bearing Race

Post by mcman56 »

This sounds like a "not to be recommended" operation for carbide. I have never heard of ceramic cutting tools . What size cuts can you take with ceramic inserts? I could use a softer material.
John Evans
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Re: Boring a Bearing Race

Post by John Evans »

There are also CBN inserts that are suitable for hard turning. I don't think I ever went more than .015 DOC . I also turned down HSS milling cutter shanks with the ceramic. Interesting thing is they also will take.001 cuts in hard material. Hard turning/milling is regularly done in commercial shops . But, if you can use a more machinable material that would be my first choice. Just as a matter of personal interest what kind of MC ?
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mcman56
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Re: Boring a Bearing Race

Post by mcman56 »

It is a 1976 Honda TL250 similar to the XL250s. The cases are split vertically and Honda used an over sized OD bearing with hole for locating dowel pin. The bearing was a custom and no longer available. I assume the dowel pin is for locating plus maybe extra insurance to prevent turning in the cases. ID and width are standard 6306 C3 dimensions,
John Evans
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Re: Boring a Bearing Race

Post by John Evans »

mcman56 wrote: Sun Nov 21, 2021 10:19 am It is a 1976 Honda TL250 similar to the XL250s. The cases are split vertically and Honda used an over sized OD bearing with hole for locating dowel pin. The bearing was a custom and no longer available. I assume the dowel pin is for locating plus maybe extra insurance to prevent turning in the cases. ID and width are standard 6306 C3 dimensions,
OK , my BIL had a new XL250 in 75-6 . Never been into that engine. Leave it to a MC mfg. for a special!! That is what got me into machining to start with, making parts for old British bikes. Internal grinding or WEDM would be best ways I would think to open your old race.
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mcman56
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Re: Boring a Bearing Race

Post by mcman56 »

Looking at all of this feedback, I may be better off with mild steel. I can turn id and od at the same time so don’t have to use a 4 jaw. I’ll try cutting the original bearing just to see how it goes
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Bill Shields
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Re: Boring a Bearing Race

Post by Bill Shields »

It is going to go badly... :mrgreen:
Too many things going on to bother listing them.
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Harold_V
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Re: Boring a Bearing Race

Post by Harold_V »

Bill Shields wrote: Sun Nov 21, 2021 1:55 pm It is going to go badly... :mrgreen:
Oh, yeah! :wink:
Without grinding or ceramic, I don't see success in one's future.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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