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  • #16
    Good enough for the Navy personnel we go out with....

    Originally posted by J Tiers View Post
    A pretty low standard.....................
    25 miles north of Buffalo NY, USA

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    • #17
      Plenty of good advise both from members and from SKF. What instrument do you guys use for measuring I.D.s +/-0.001"; if at all possible please include a link to the vendor.

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      • #18
        This reminds me of a young machinist apprentice I had working for me. I had him turning shafts for a press fit of a cam follower bearing. I was checking his work and the shafts were as much as 0.005” oversize. I called him on it and he says “I can get those bearings on.” I walked in the office and got the bearing catalog and showed him how much information there was for fitting this bearing. I asked him why he thought some engineer would spend so much time to produce all this information if it wasn’t important?

        He had been given a classic old Corvette and was going to replace the rear axle tapered roller bearings. He brought the axle in and I asked him how the axial clearance gets adjusted. He said his shop teacher told him there was no adjustment! I told him we wouldn’t be doing this until he found the specs for this axle. He did as I asked and found out the spacer that came with the new bearings was oversize. You had to assemble, measure the play and then grind the spacer about 0.001” less than exact length to produce preload. I helped him do it and taught him how to measure the play with dial indicator. Sad this teacher was giving these students such bad advice.

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        • #19
          Without knowing anymore info than what the OP stated I would say you are better off having the bearing a very light slip fit and securing with retaining compound vs having a bearing to tight in the bore.

          It is also easier to achieve this if you don’t have the tools or are not up to the task skill wise of measuring bores. Technically, if you have the bearing you wouldn’t actually need to “measure” anything to achieve that fit, just keep checking the bearing against the bore.

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          • #20
            Originally posted by rodelu View Post
            Plenty of good advise both from members and from SKF. What instrument do you guys use for measuring I.D.s +/-0.001"; if at all possible, please include a link to the vendor.
            Big topic.... Internal mics, snap gauges, 3 point mics ($$$ and limited range) and many more. In reality, the only thing affordable (if that's a concern) are telescoping snap gauges, but these are highly technique sensitive; you need to practice practice practice, even then it an "average" of readings. These bore gauges work "ok" Igaging 34-715 $114.12 Internal Bore Gauge Set - 34-715 | Zoro.com . I have a similar quality set from Mitutoyo. Nice, 3X as expensive, and still needs practice to be confident, but I can resolve a few 10ths. With these a quality indicator is important. Way cheaper if you buy the generic imports.

            +/- 0.001 (over what diameter?) is not too difficult, BUT that's generally not accurate enough for smaller bearing fits. +0.001 is a press fit; -0.001 it will fall in. Surface finish is critical for accurate fits. I still like to make a go/no-go gauge for critical fits.. way easier then fiddling with internal. Watch out for temperature... make sure everything is the same when measuring to 10ths.

            And... a problem for most starting out - how to hit the number you need? "sneaking up" (we all do it) rarely works well if you need a guaranteed surface finish. Emery paper on a stick can work with great care but you will be low and high in spots on a blind bore. A "correct" (lol) technique to start your measurements way out, and make the final two exactly equal cuts on reasonable depth. Takes courage and trust in the machine and measurements to do that on a part that will be trashed on error 🙄😊
            Last edited by lakeside53; 12-25-2021, 04:34 PM.

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            • #21
              Originally posted by rodelu View Post
              Plenty of good advise both from members and from SKF. What instrument do you guys use for measuring I.D.s +/-0.001"; if at all possible please include a link to the vendor.
              I use telescoping gauges but lakeside has touched on the downside of them above. I’ve also turned plugs to use as reference gauges as also mentioned above.

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              • #22
                Different ABEC bearing grades have decreasing internal clearances as the prices increase, use the bearing manufacturers recommendations for the annular bearing that you are using.

                As for measuring bearing bores I use dial bore gauges, this is a Mitutoyo .4000" to .7000" tenth reading bore gauge, about $350.00 From MSC. The smaller they get the more expensive they get.

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                • #23
                  Also, depending on the customer an external bearing diameter may look like so.
                  30 MM annular bearing fit.
                  Last edited by Bented; 12-27-2021, 09:07 PM.

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