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Cutting down a bearing race

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  • Cutting down a bearing race

    I need to cut a timkem bearing race to fit a special application. I need to cut only 1/2 of the shell, so I can hold it in my chuck. Has anyone had any success cutting a hardened bearing with a carbide tool? I need to remove a .200. I have a tool post grinder, but it will take forever to remove that much. Any thoughts? Stan

  • #2
    No experience cutting bearing races with carbide. What about using a zip wheel on a die grinder to rough cut the race while in the lathe and then using the tool post grinder to do the finish passes.
    I shouldn't have to mention protecting the lathe from abrasives but I will.
    Home, down in the valley behind the Red Angus
    Bad Decisions Make Good Stories​

    Location: British Columbia

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    • #3
      I need to remove a .200.
      Is that a typo? Removing .1 off the wall of just about any bearing other than the larger sizes up around 4 inch OD and over would see you either leaving the wall VERY thin and prone to distortion or would cut through the thinner portion of the inner race. through the wall and into the balls inside.

      You won't be able to hold it directly because the jaws of a chuck would badly distort the ring. So you would need to turn a holder of some form which allows you to press fit the portion you don't need to turn down into a recess. The recess will ensure that the outer race stays round and will hold it very nicely.

      Not a clue about how well it would machine. But if you have some cheap smaller scrap bearing kicking around have a go at it with whatever carbide tooling you have.
      Chilliwack BC, Canada

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      • #4
        Originally posted by 1937 Chief View Post
        I need to cut a timkem bearing race to fit a special application. I need to cut only 1/2 of the shell, so I can hold it in my chuck. Has anyone had any success cutting a hardened bearing with a carbide tool? I need to remove a .200. I have a tool post grinder, but it will take forever to remove that much. Any thoughts? Stan
        Hey Stan, I have had very good success cutting ball bearing external races by mounting a 4 or 4 1/2 " angle grinder on the toolpost and using 1/16" X 4" cutoff wheels on the grinder. On 1"-2" od bearing with a bolt, nut and large washer to to act as a mandril and keep the bearing from rotating and running the lathe at 150-200 rpm then feeding the grinder by hand you are thru the bearing shell in less than a minute. I use a mist coolant and paper towels over the bed and carriage to keep it all contained and clean. Learned this from an old smith in the 60's and he used a kids squirt gun for his coolant. The interesting part to this is with a bit of care the bearings suffer no damage other than being made shorter for special applications when the proper sized parts were not readily available.
        steve

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        • #5
          Just Chuck it up and cut it gently with a carbide cutter. Works fine. I just cut a groove for a retaining ring in the center of a double row bearing. Easy. I touched up the carbide cutter a few times with a diamond wheel because I didn't want to generate any heat into the race. Worked fine. I put masking tape on the sides of the bearing to keep the chips out. This bearing was for the mainshaft on an old vw transaxle.

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          • #6
            I've cut bearing races. It takes a bit of playing around, but not really a big deal. Keep everything as short and stiff as possible. Use a keen tool, small tip radius (don't expect it to last very long). The chips are tiny blue curls, almost like dust.
            The suggestions above no doubt work fine, but there is nothing wrong with you original idea.

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            • #7
              OK. This is something I've done a fair bit of - very successfully. I use a ceramic tip, not TC. Never got a useable finish with any TC tips, whereas the ceramic tips don't even look like they are working hard. Nice finish, accurate dimensions and all the heat goes into the chips. Ceramic tips are about the same price as TC tips. Be VERY careful NOT to do any interrupted cuts with them. They will chip on the first rotation.
              BTW, I like using ceramic tips a lot. They allow much faster removal of material without generating much heat - it all seems to go into the chips. This is on a hobby lathe, not some multi-ton machining centre (that they were designed for of course).

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              • #8
                "Ceramic tips are about the same price as TC tips."

                really? would you mind sharing where you get them?

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                • #9
                  Originally posted by dian View Post
                  "Ceramic tips are about the same price as TC tips."

                  really? would you mind sharing where you get them?
                  I found a box on eBay NOS that were cheaper than my average TC tips of the same size, it's too boring for many but if you check the auction sites regularly for what you want it sometimes comes up ;-)

                  - Nick
                  If you benefit from the Dunning-Kruger Effect you may not even know it ;-)

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                  • #10
                    In the past I've cut down Timken cups to use them for other purposes. The best thing I found was CBN (cubic boron nitride) inserts. Not cheap and they do not like interrupted cuts at all. But they'll cut bearing races like butter.
                    Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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                    • #11
                      Originally posted by Spin Doctor View Post
                      In the past I've cut down Timken cups to use them for other purposes. The best thing I found was CBN (cubic boron nitride) inserts. Not cheap and they do not like interrupted cuts at all. But they'll cut bearing races like butter.
                      Amazing what you can learn with an open mind. A lot better than a typo, thanks for posting.
                      Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router

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                      • #12
                        Originally posted by Spin Doctor View Post
                        In the past I've cut down Timken cups to use them for other purposes. The best thing I found was CBN (cubic boron nitride) inserts. Not cheap and they do not like interrupted cuts at all. But they'll cut bearing races like butter.
                        What size lathe you used?
                        Does anyone with experience how CBN inserts work on a smallish home lathe?

                        I have used random carbide inserts to do it couple of times but the inserts are gone pretty fast. 1 usd insert used per bearing is still better than grinding with my equipment.
                        Location: Helsinki, Finland, Europe

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                        • #13
                          It's called "hard turning". Usually done on rigid, commercial grade machines with expensive tipped inserts.

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                          • #14
                            I have a 13 inch old south bend. Very well built. Thanks for the answers I will do a practice cut on a old race. Looks like it's possible. I have a 61 Triumph TR5AC. It seams to be a little different than other models. This bearing is for the fork steering. Stan

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                            • #15
                              I was surprised to find ceramic inserts at aliexpress for indeed the same price as the carbide inserts. Haven't tried them yet though on anything.

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