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Rotab repair ideas

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  • Rotab repair ideas

    I was the successful bidder on the Troyke table this morning, seller claims that the only damage is what the pics show, I'm looking for ideas for repairing it, my first thought is an epoxy with a release agent on the worm and let it make the proper contour, could probably run it in halfway from each side and note which degrees the damage is at and try and avoid that area on certain jobs??

    I had found another 12" horizontal in WA state in the fall that I likely could have grabbed for next to nothing that had similar damage but passed on it as that would require some healthy angle plate..........LOL

    Worst case scenario would be I have to cut it out and fab up a new ring gear and shrink it on but I'd like to avoid that if possible.......
    Last edited by hardtail; 03-27-2009, 12:08 AM.
    Opportunity knocks once, temptation leans on the doorbell.....

  • #2
    Just drill some one or two holes where each tooth used to be, and install some roll pins that are a little larger diameter than the tops of the teeth. Do a little grinding/polishing to relieve any binding as the pins go past the worm.

    Last edited by winchman; 03-27-2009, 04:05 AM.
    Any products mentioned in my posts have been endorsed by their manufacturer.


    • #3
      A Combination of the two ideas, but with a different moulding idea.
      Metal loaded epoxy reinforced with metal pins in the teeth. Use a section of good teeth as a mould for the epoxy. Use Silcone rubber moulding material to make mould (higher end craft/art shops have this). You can get bronze, steel and aluminium loaded epoxies designed for repairs like these. (see this link)
      The pins will give you the strength and the metal loaded epoxy the bearing area.
      Fix these pins in to the ring gear then mould the epoxy around them using the silcone mould.
      I suggest two pins per tooth (one at each end where the teeth are widest).

      With this approach you can try it out, by building a test piece , without the danger of gluing the worm together.

      Last edited by derekm; 03-27-2009, 06:48 AM.


      • #4

        I think I'd be doing a full "pull-down" and going over every part of it - in detail.

        There must have been one hell of a whack to have caused that damage.


        • #5
          I have seen gear damage such as this repaired by cutting/milling away the bad teeth and inserting a new metal piece in the slot and welding or brazing it in. The teeth are then filed in to match. The plug could be roughed in before welding it in place. Its only practical if the damage is only on a couple teeth because of the amount of filing/fitting necessary.

          I have seen it done by welding up material on the bad teeth and reshaping them but the strength is not nearly as good as inserting a new section.

          I have doubts about molding new teeth. The forces were enough to strip the original metal teeth and I doubt the molded teeth would last under the stress.


          • #6
            what metal is the ring gear?
            Last edited by derekm; 03-27-2009, 08:46 AM.


            • #7
              The other I looked at was more washed out across more teeth if I recall, I will be looking closely at the worm, unfortunately I won't likely see this thing for about 6 weeks until I go to BC and WA. The table looks near new and I can't see any damage on the top edge from a fall at around 200 degrees?????

              He claimed this was the only damage but if it fell on the handwheel these may have been the teeth that were engaged with the worm at the time???? I hope not as that was one of my questions.......wait and see.
              Last edited by hardtail; 03-27-2009, 09:04 AM.
              Opportunity knocks once, temptation leans on the doorbell.....


              • #8
                Now I see it from above it looks like cast iron....
                This link has successful tooth repair mentioned using pins and nickel bronze brazing rods.
                You might consider casting the nickel bronze over the pins to reduce the amount of fettling needed.


                • #9
                  Thats an un-boltable ring --- I would price one...


                  • #10
                    they make a brazing rod for building up broken gear teeth that is pretty hard and still workable. i have used it to repair the gears in log loader rotary grapples and have good service out of it. when i first tried it i figured it would strip right off because loggers are very hard on equipment but have been very surprised with the longevity.


                    • #11
                      That was my thought to when I saw the screws. Why not just try to buy one. If not available then I would use two small pins in each tooth area and then braze the whole area up. Then make a cutter to match the good tooth area and recut the brazed teeth.

                      I too am wondering how it got broken and I would look it over real close as there may be other damage. You may have to buy another one for parts which may not be a bad idea anyway.
                      It's only ink and paper


                      • #12
                        Braze repair

                        Use Harris-Welco 17-4 nickel silver brazing rod to build up the tooth area and then recut the teeth with an air die grinder and small carbide burr.

                        The braze is stronger than the base material.

                        I have used this extensively on a Sheldon lathe, Logan shaper vise and Metcalf and Emmert patternmakers vises.


                        • #13
                          Originally posted by Carld
                          ...then I would use two small pins in each tooth area and then braze the whole area up. Then make a cutter to match the good tooth area and recut the brazed teeth.
                          Years ago I needed a a replacement drive gear for the drum on my concrete mixer before I had some equipment. I couldn't find one. I went to a big machine shop and told them my problem. A 'real' new gear was big bucks, for me, so the owner came up with plan 'B'. He had an apprentice build up the gears with welding rod and then 'machined' it with an angle grinder. All the hard faced teeth do not show wear after lots of use.