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Need confirmation on technique for replacing bearings

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  • Need confirmation on technique for replacing bearings

    I'm replacing the bearings on my table saw blade arbor (1 was scritchy). I think that I've figured the sequence appropriately, but I'd like confirmation, or suggestions for a better way.

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    The blade flange is integral to the arbor so the left bearing has to go on from the right.

    1 - press the left bearing onto the shaft
    2 - press the shaft & bearing into the housing
    3 - press the right bearing onto the shaft & into the housing simultaneously

    For all the presses I have "pushers" that put the pressing force on the race being seated. I.e., the force will never be through the balls.

    Thanks

  • #2
    Without seeing exactly how it came apart it sounds like you've got it right. Just be sure you've got any spacers
    in the right position and facing the right way and you should be good. I just (like 10 days ago) replaced the
    bearings on a 12" General saw and the procedure was the same. However you do it you're going to have one
    bearing that goes on the shaft and in the housing at the same time. In theory you could first push the second
    bearing into the housing and then press the arbour and first bearing in but it's generally easier to push the
    second bearing in last...
    Keith
    __________________________
    Just one project too many--that's what finally got him...

    Comment


    • #3
      Bob, I think your on the right track. That arbor housing almost looks like my Craftsman. What LK said is correct. I think that after studying it for a while you'll see that there is really only one way to assemble it.
      I would think it's pretty straight forward that you press the one bearing on the shaft up against the flange and slip the arbor into the housing seating the one bearing, that one may float a little. Not sure how that bearing seats in the housing or if it floats and the snap rings are on the other side. I've seen a few different configurations in the past.
      So I guess your main question is how to go about installing the bearing on the pulley side. You could go either way. Press the bearing in the housing and push the arbor through or push the bearing in the housing and on the arbor at the same time. It now becomes a question of what fits tighter, the bearing in the housing or the shaft through the bearing inner race. That should tell you.

      Mine was a little bit different. I had to press the flange off to remove the bearing. The bearing on the flange side floats. The alignment is all held by the bearing on the pulley side. The bearing on the pulley side had a snap ring behind it which you cant get to unless you remove the bearing, no need to remove that inner snap ring anyway. There is another snap ring that holds the bearing in place and one on the shaft that holds the shaft to the inner race.



      This is how I assembled mine. I don't think I have a pic of the other side.



      JL....................

      Comment


      • #4
        I hope your using sealed bearings for the replacements. I'm sure the originals were shielded.

        JL..................

        Comment


        • #5
          You have to be careful when replacing bearings like these. Sometimes the shielded bearings are there for
          a reason--at higher RPMs friction from the seals in sealed bearings will create too much heat...
          Keith
          __________________________
          Just one project too many--that's what finally got him...

          Comment


          • #6
            Bob, I would warm up the casting to about 250 F before inserting the bearings
            It's not a lot, but will lower the arbor pressure and result in a better fit.
            Thermo fits (Shrink) have twice the retention of press fits
            To maximize this you could freeze the arbor shaft before the first bearing and after
            Rich
            Green Bay, WI

            Comment


            • #7
              Originally posted by Rich Carlstedt View Post
              Bob, I would warm up the casting to about 250 F before inserting the bearings
              It's not a lot, but will lower the arbor pressure and result in a better fit.
              Thermo fits (Shrink) have twice the retention of press fits
              To maximize this you could freeze the arbor shaft before the first bearing and after
              Rich
              On a lot of applications like this one of the bearings will be quite loose so it can float in the bore. It can be done both ways
              so measure your bearings and bores to see how the manufacturer of the saw designed the setup. No need for any heat if
              you've got a floating fit...

              Keith
              __________________________
              Just one project too many--that's what finally got him...

              Comment


              • #8
                Originally posted by Rich Carlstedt View Post
                Bob, I would warm up the casting to about 250 F before inserting the bearings
                It's not a lot, but will lower the arbor pressure and result in a better fit.
                Thermo fits (Shrink) have twice the retention of press fits
                To maximize this you could freeze the arbor shaft before the first bearing and after
                Rich
                There really is no need to heat and cool anything, the factory never went through all that when these were mass produced.

                JL...............

                Comment


                • #9
                  Thanks for the comments - I was pretty sure that I was on the right track, but I've been wrong before.

                  The original bearings were very tight in the housing & on the shaft - they had to be driven out with a hammer. Assuming the replacements are close in size, they will not slide or be tapped in.

                  The left bearing is held in place by a seat in the housing & by the blade flange. The right bearing by a seat & a threaded ring. The shaft is held on the pulley end by a nut against the inner bearing race (seems like a bad idea to have an axial load on the bearing). Actually, the fit was so tight, that I'd say they were being held by that & the other stuff was/is redundant.

                  Edit - there is no axial load on the bearing: there is a spacer between the inner races & the flange bears on the left inner race, so the nut bears on the right inner race, which bears on the spacer, which bears on the left inner race, which bears on the flange/shaft. Bottom line is that the nut puts tension on the shaft.

                  The original bearings (from 30+ years ago) were sealed and the ordered replacements are also.
                  Last edited by Bob Engelhardt; 03-29-2020, 09:42 AM.

                  Comment


                  • #10
                    I would seat the saw blade end bearing against the shaft shoulder and secure with nut and spacer. Press or tap bearing into housing until outer race is seated. Clean and lightly oil all parts to aid in assembly. Heating housing while not necessary may let the bearing just drop in. Install rear bearing and adjust end play with nut. Run saw to warm everything and recheck end play/ bearing preload. If tapping things together with a hammer, use only wood, plastic or soft metal drivers to seat bearings.

                    Comment


                    • #11
                      Originally posted by Bob Engelhardt View Post
                      Thanks for the comments - I was pretty sure that I was on the right track, but I've been wrong before.

                      The original bearings were very tight in the housing & on the shaft - they had to be driven out with a hammer. Assuming the replacements are close in size, they will not slide or be tapped in.

                      The left bearing is held in place by a seat in the housing & by the blade flange. The right bearing by a seat & a threaded ring. The shaft is held on the pulley end by a nut against the inner bearing race (seems like a bad idea to have an axial load on the bearing). Actually, the fit was so tight, that I'd say they were being held by that & the other stuff was/is redundant.

                      Edit - there is no axial load on the bearing: there is a spacer between the inner races & the flange bears on the left inner race, so the nut bears on the right inner race, which bears on the spacer, which bears on the left inner race, which bears on the flange/shaft. Bottom line is that the nut puts tension on the shaft.

                      The original bearings (from 30+ years ago) were sealed and the ordered replacements are also.
                      Not surprising since anything that that old will have dried grease / oil, sawdust and even surface rust making them difficult to remove. I'm surprised the original bearings were sealed. That's the best way to go as the fine powdered saw dust tends to dry up the grease prematurely.

                      JL...................

                      Comment

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