Thread: Machining bearing OD with ceramic inserts ?

I want to try reducing the OD of some roller bearings or similar really hard steel using a tool holder with a ceramic insert. Can someone recommend a tool holder and insert step up which might be suitable?

Might need a bit more information:
What sort of machine do you Have?
How many horsepower?
What size toolholder shanks can your toolpost take.
You can get CBN inserts in most formats, what inserts do you currently use?
Do you expect these bearings to be usable for any sort of precision application?

It is a 16by40 probably with 10HP on 3 phase weighing about 2000kg. I use Aloris CXA tool holders so can take up to 25mm. The bearings just need to be turned down to fit. For example a dish washer needs a new bearing but apparently no off the shelf type fits. I will try an aim for accuracy. I also have a tool post grinder which can grind bearings down, but want to try inserts. Not sure on what type of inserts I have. Triangle types, dont laugh. I will have to look it up.

Thats plenty of power, you should be able to get triangular TNMG CBN inserts off ebay for $30 each or so, the one thing I found you need for hardturning is horsepower.
I would say you will get better results off the grinder though, very hard to hold the race hard enough to hard turn without distorting it in relation to the id.

Rather than turning the brg you might be better of aiming for a smaller OD brg and make a sleeve to fit it.
Otherwise you will have to make a mandrel to hold the brg, if you try to hold it in the chuck by expanding the jaws inside the brg shell it will likely distort when you have it tight enough to turn it.

The inserts fit in standard holders. I have hard turned on a noodle of a lathe without any problem. The DOC will be limited. I use Kyocera Cermet inserts extensively for both milling and turning. I personally feel Kyocera is one of the better brand for this type of insert. Choose whatever shape you like to suit your current holder. Personally I would hard turn and then finish with the toolpost grinder.

I find it difficult to believe however that a bearing isn't available off the shelf for that application.

Excellent responses. Make a sleeve is a good idea. Hard turn and grind sounds good. Kyocera it will be. We have a Kleenmaid diskwasher and the top fan bearing became very noisy. The techo says you cannot get a replacement. I will see what is around and modify to suit.

Originally Posted by topari

The techo says you cannot get a replacement.

If this is an otherwsie standard roller bearing I would respectfully suggest your techo is likely full of it. It may not be available as a spare part, but is extraordinarily unlikely that it would not be available as a regular bearing. When designing a product there would have to be an extremely good reason to use something that isn't available off the shelf, particularly for a consumer product. Before turning anything I would pull the old bearing out and check the numbering it has. If that turns up nothing I'd measure the diameters and see what it was.

Originally Posted by Pete F

The inserts fit in standard holders. I have hard turned on a noodle of a lathe without any problem. The DOC will be limited. I use Kyocera Cermet inserts extensively for both milling and turning. I personally feel Kyocera is one of the better brand for this type of insert. Choose whatever shape you like to suit your current holder. Personally I would hard turn and then finish with the toolpost grinder.

I find it difficult to believe however that a bearing isn't available off the shelf for that application.

Hi Pete
I worked for major world wide airconditioning company who also made the automotive aircon compressors (York)

I used to run a York compressor as an air compressor ticking over at some 2500rpm.....I digress....The rear and front crankshaft bearings were not available from bearing supplier (even the USA) except from York.

I guess they were able to ask err tell, the bearing manufacturers to fabricate just for them based on volume. Before the rotary's came out every aircond car used a York compressor. I cant recall anything else being available until Tecumseh made an after market which bolted straight on. Main difference was York all crankcase V Tecumseh Steel casting.

Originally Posted by Pete F

If this is an otherwise standard roller bearing I would respectfully suggest your techo is likely full of it.

No argument from me. My wife organised the techo to come out. You ever meet people and think what a smart a-rse ? That's the impression I had. Probably only deals with women. From now on I deal with consumer appliance problems in our house.

What was so special about a "York" bearing?

Sure, like I said above, and to quote myself "When designing a product there would have to be an extremely good reason to use something that isn't available off the shelf, particularly for a consumer product." An automotive compressor is not a consumer product and it's also quite possible they had a good reason to specify something different. But in 99.99% of the times I see, when somebody says "It's not available" or "It's special" it means they likely rang up the spare parts department, were passed on that message, and that's what they've run with. The answer is invariably just to look harder.

Bearings are almost always nothing special. They will have an ID, an OD, and will be of a particular design. They normally run in specific nominal sizes, some more common than others. If you're the chief designer for "York" or anyone else you don't just commission ABC bearing company to produce a bespoke bearing for your particular widget just for a laugh and a giggle. There would have to be a bloody good reason to do that. It's not to say it doesn't happen, just that it's not as common as some people suppose. If your name happens to be Komatsu and you need a 1 tonne bearing for a mega-digger, you're not going to get that off the shelf. But of your name is Dishlex my money is going to be on them using an off the shelf component, as much as to provide competition for their suppliers as about a billion other reasons.

Giving an over view of the situation.....if that bearing has reached its usable life is the rest of the machine likely to drop its bundle?.....just thinking out loud

If you google the bearing dimensions, you may well find even a very odd bearing being easily available. I found that when I needed a bearing with an imperial OD and a metric ID. No problem - off the shelf... to my very great surprise....
But back to original question: I did have to nodify the width of a bearing, because I stuffed up in an design. I used a regualr ceramic insert and the bearing cut beautifully. Nice blue swarf and a great finish. That's with the bearing in a three jaw chuck and normal steel speed and feed.

Bearing dealers have a pretty good variety of sizes now, 30 or 40 yrs ago we were still repairing stuff from the 1920's 1930's and so on.
A lot of, for example, engines, gearboxes, magnetos, pumps, chainsaws or whatever POS had odd sized brgs that just could not be obtained, but l wouldn't be surprised if those brg's that we couldn't get then can be got now.

Hi Guys,

One possibility for using a bearing that has the correct bore but a small diameter is those thin wavy spring steel rings that are specifically for taking up a small gap between them, I've seen similar used on shafts running in oversized bearing bores.

They are called "Tolerance Rings"

l225.jpg 225.jpg