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    I was given this shell mill. It has 2 damaged threaded holes that was drilled out off center. I had the idea of drilling the threaded holes oversized and tapping them out to go the larger screw and drilling and tapping the screw to the size of the original torx screws

    The other method is to weld up the original holes up and drill and tap them to the torx screw size.

    Any suggestions and comments

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  • #2
    I can see why it was given away, I suggest you give it to someone else who also can't use it.



    • #3
      If it has the wall thickness to take it, as you suggest, make a threaded bush, tap to the od thread, keep original screw thread size on the inside, loctite or stake insert bush in. Rather like the timesert system. Or use timeserts. I'd do the bush on the lathe first rather than trying to centre drill in situ.
      But... is it worth that much effort? unless it came with a mass of free very odd shaped inserts, it might be a tough call to even just buying one on ebay with smashed up inserts that fit your stash.


      • #4
        Looks like the insert pocket is also mangled...

        Chinese mill bodies might not have the perfect tolerances like new Sandviks, but they are probably way better than this is ever going to be anymore and very reasonably priced if the model you need is one of the more common models.
        Location: Helsinki, Finland, Europe


        • #5

          I wouldn't bother fixing it either. But if you have inserts for it, there is no law that says you need to fill every seat with an insert. You can safely run one or more empty if you wish. Just need to cut back on the feed. I have often removed all but one insert to get a "flycutter " effect from an multi-insert face mill.
          If you think you understand what is going on, you haven't been paying attention.


          • #6
            That’s seems like his plan. I’d use a carbide mill and open the hole up then drill and tap to the larger size. Probably a 1/4 28 or a 5/8. Drill and tap the smaller hole in a set screw and lock tight it in.

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