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Turning down OD of a tapered roller bearing race.. Timken cup

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  • #31
    OK, had to try myself:
    Turned a tight slip fit mandrel from piece of barrel:



    Carbide cuts "ok" but wears too fast to hold size. Turned the OD to 21.90mm but I got at least 0.02mm taper one way or other. Start from left and I get opposite taper.



    Time to bring out the big guns. Sandvik CBN insert, previously sharpened on diamond wheel and lapped to mirror with diamond paste:


    OK, this cuts much better and won't wear down halfway in the cut. Lets aim for 21.850mm:


    That was suspiciously easy.. lets say we want actually 21.800mm OD:



    Good enough for no other purpose than satisfying my curiosity..
    Location: Helsinki, Finland, Europe

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    • #32
      Yes i had thought of line boring.
      Thanks so much, this is the info I am looking for, on actually turning it.. I fear my south bend may not do it.
      one thing I got with the SB 9 was brake lathe tooling, 3 edge insert on a 3/8 shank, a bit of rake built in,, it seems to cut harder stuff. My idea was to suffer through the bulk of cut leaving 8 thou or less, then setting up a Dremel to grind to finish.. might work
      or just build a soft race. But what Matt showed, actually doing it, is encouraging..

      the brake lathe tooling don't think I have see it mentioned here, when I got the lathe there was not any small import carbide stuff like today.

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      • #33
        One thing I forgot to mention: You might need to machine the mandrel so it actually centers on rolling element contact surfaces. The other dimensions/surfaces in the outer race bore are not necessarily concentric with the outer surface! That was the case with my bearing but it didn’t matter as I was interested to only make chips.

        Turning a matching taper to the mandrel would be major PITA so maybe mount the mandrel in 4-jaw and center on bearing outer surface before turning. With bit of bad luck the rough bored features of the bearing hole are not even round
        Location: Helsinki, Finland, Europe

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        • #34
          Matt did you get the feeling it was a hard skin, or hard all the way.

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          • #35
            Originally posted by 754 View Post
            Matt did you get the feeling it was a hard skin, or hard all the way.
            Hard all the way trough like ball bearing races usually are. IIRC US made(Timken) tapered roller bearing races are/were often case hardened for some historic manufacturing reasons. (Americans did not have easy access to suitable ores like SKF in Sweden had)
            European (SKF, INA, FAG) origin are typically made of trough-hardened steel.
            Last edited by MattiJ; 06-19-2020, 02:46 AM.
            Location: Helsinki, Finland, Europe

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            • #36
              Was a regular thing back in the day to replace cup & cones with taper rollers, and back then there were not the conversion kits that are available today.
              You had to make the spacers for the next size down TR brgs and sometimes modify the stem or make a completely new one, hence it was immaterial whether the new TR brgs were metric or imperial, you just bought what would fit and modify to suit.
              Hence Imperial brgs in a Yamaha neck and metric brgs in a BSA.
              Is this not feasable?

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              • #37
                Originally posted by thaiguzzi View Post
                Was a regular thing back in the day to replace cup & cones with taper rollers, and back then there were not the conversion kits that are available today.
                You had to make the spacers for the next size down TR brgs and sometimes modify the stem or make a completely new one, hence it was immaterial whether the new TR brgs were metric or imperial, you just bought what would fit and modify to suit.
                Hence Imperial brgs in a Yamaha neck and metric brgs in a BSA.
                Is this not feasable?
                It would be quite feasible if smaller bore was on top, this happens to be on the bottom. .. and there is a nicely machined stem there with nicely chromed nuts on each end , that fits the girder fork. Once my lathe and mill are wired up, i have a lot more options.

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                • #38
                  It would not be hard to assemble the bearing and rotate it to see if the inner edge of the small cone actually runs true. If it does, making the mandrel would be easier. Even if it does not run true. the mandrel could be adjusted in a four jaw independent chuck to run true. The od of the bearing will definitely be true to the bearing track. A problem could arise if the lathe can only hold small tooling, as it might be hard to get cbn inserts id small sizes. It would be a good idea to measure the bore of the frame at several angles to find out exactly how out of round it is assuming the bore predated the welding. Even if the bore is distorted slightly, the shoulder that the bearing sits up against should be ok, so turning the bearing down so it is easy to fit in the bore and will not be distorted is the best option. Then Loctite 638 bearing fit will hold it safely and securely.
                  Fortunately the bike is a chopper and will never be expected to handle like a road racer.
                  What is the bearing number?

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                  • #39
                    The bearing numbers are L44649 and L44610, not sure which is the cup... should be around 1.980 od.
                    Neck bore beingout of round is not an issue (at this point ), it will likely be bored to proper size , before going on the road.
                    Last edited by 754; 06-19-2020, 01:24 PM.

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                    • #40
                      Not related, but...
                      I currently have 4 cylindrical grinders in my shop, including a B&S #13
                      that is exceptionally nice.
                      I got them to be able to do custom hard stuff, just like bearing races.
                      Am I the only one who thinks these machines are handy for hard work?

                      -Doozer
                      DZER

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                      • #41
                        Geez that is good news maybe,... you certainly have the equipment. As far as I know no one around here has cylindrical grinders except hydraulic cylinder repair shops , and talking them about fork tubes , they are very high priced and don't seem to want to do the work.
                        I had a surface grinder I used to use, pretty sure it could be done on there, mounted on a stub to a 5C collet, and turned by a spin indexer.

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                        • #42
                          another suggestion if you have access to your lathe is to made a standalone headtube bearing borer. Make two large bushings sized for a press fit in the inner part of the head tube (or maybe one to fit in the upper cup), drilled and reamed for a tight sliding fit with a 3/4" shaft. Make the equivalent of a flycutter or something like that and pin/screw/weld it onto a 3/4" shaft with a 1/2" hex or 3 flats on the end. Make a hole/ slot for a 1/4" HSS bit in the flycutter thing. Press in bushings, slide in shaft and zero cutter to bore of lower bearing cup. Advance the cutter a wee bit and use a drill to cut the lower bearing cup. Remove, measure, advance cutter a wee bit more. Repeat until on size. Fit standard bearing. Put a bar of chocolate in the post to me

                          Don't know about motorbikes, but these kinds of jigs are used all the time to face and ream bearing cups on bikes. Ideally you'd want to make a one piece cutter to exact size, but that's a lot of work for a one off and you'd be able to use this on other stuff.

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                          • #43
                            Originally posted by Doozer View Post
                            Am I the only one who thinks these machines are handy for hard work?
                            not just for hardened work, but improved accuracy and finish on about anything. Mine is just a motorized work head on a T&CG so no where near as nice as a proper cylindrical grinder (I've no space for that) but it definitely improves the shops capabilities.

                            A T&CG is just a great addition and with the grinding head more the doubles its usefulness




                            in Toronto Ontario - where are you?

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                            • #44
                              Originally posted by Mcgyver View Post
                              ....A T&CG is just a great addition and with the grinding head more the doubles its usefulness....
                              Glorious ! ! !



                              I have a Covel which is a dedicated cylindrical grinder.
                              My Brown Sharp #13 is considered a universal grinder
                              but it has origins from their dedicated cylindrical grinder
                              line, so set up as such, it is a very good machine.
                              I also have a very old Heald #7 I.D. grinder, probably
                              from the 1930s. It is very stout in construction. I need
                              to get it restored sometime. It has a Parker-Majestic
                              spindle, need to collect some Red Ring spindles off
                              ebay once I get her running. I have a small Van Norman
                              cylindrical grinder I don't need. Perfect for home shop.
                              Come to Charlotte and make me an offer.

                              --D
                              Attached Files
                              DZER

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                              • #45
                                Nice, the B&S looks like you just uncrated it. If I ever get out of Dodge and back to the country, I'd like enough space to get a real grinder.
                                in Toronto Ontario - where are you?

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