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Cheap&Easy Long Drill Bits

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  • #16
    Nice!

    I've shrink fit a shaft onto a drill bit before to get a one-off job done. It worked well, but was more time consuming. I also had to turn the shaft off the drill bit after.

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    • #17
      Nice selection of ideas for drill bit extensions.

      I've made several 8" to 16" extensions for 1/8"" to 3/8" drill bits over the years and settled on the high strength loctite method. Quite often I used 4130 chrome moly tubing for the extension. Ream or drill the tube I.D. for a snug fit, apply the loctite in the tube and on the drill bit, assemble and you're ready to go in a few minutes. Then to change the drill bit just heat the extension and pull the bit out. I've never had a drill bit come loose but then again when you have a long extension like that on a drill bit you wouldn't be hogging into it anyway.

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      • #18
        Originally posted by kev74 View Post
        Nice!

        I've shrink fit a shaft onto a drill bit before to get a one-off job done. It worked well, but was more time consuming. I also had to turn the shaft off the drill bit after.
        Good idea with the shrink fit,will try that why do you machine the shaft away after installed?

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        • #19
          Shrink fit on small sizes is a bit demanding on machining and drill sizes though. Expansion being a % of the original size. I've often used slightly smaller number or letter size drills to hold pins or drill bits of some nominal inch size since I know that the inch drills tend to drill a bit oversize if I'm after a press fit. Even to the point of knowing I'd be looking at a press fit by design in some cases.

          For fast results to get a job done in a hurry I'm liking the options of crimping as TTT started out this thread or nearly instant results from a close slip fit and CA glue. When we're in a hurry even the hour or two for the Loctite options is going to feel really slow. Solder or silver solder is pretty quick. But not as quick as a press fit or a drop of CA glue that cures in only a few seconds.
          Chilliwack BC, Canada

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          • #20
            Originally posted by BCRider View Post
            Shrink fit on small sizes is a bit demanding on machining and drill sizes though. Expansion being a % of the original size. I've often used slightly smaller number or letter size drills to hold pins or drill bits of some nominal inch size since I know that the inch drills tend to drill a bit oversize if I'm after a press fit. Even to the point of knowing I'd be looking at a press fit by design in some cases.

            For fast results to get a job done in a hurry I'm liking the options of crimping as TTT started out this thread or nearly instant results from a close slip fit and CA glue. When we're in a hurry even the hour or two for the Loctite options is going to feel really slow. Solder or silver solder is pretty quick. But not as quick as a press fit or a drop of CA glue that cures in only a few seconds.
            Loctite 638 works really fast on close fitting tolerances. Slip fit usually turns solid in less than 10 seconds so beware.
            Give little extra heat(100c or so) it's ready for action after parts have cooled down.
            Location: Helsinki, Finland, Europe

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            • #21
              Before I retired I needed to drill some holes in a machine very close to a long perpendicular surface and needed a long drill to do it. I took a piece of cold rolled rod only 1/16" or so larger than the drill and in a lathe drilled a hole in the end similar to what the OP did. And a small vent hole at the bottom of this hole and then used loctite to hold the drill in this extension. Worked great. I think I was drilling some tap holes for a 1/4-28 thread, but that's a while ago so not sure. I had a pilot drill and then the tap drill done this way.

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              • #22
                Originally posted by MattiJ View Post

                Loctite 638 works really fast on close fitting tolerances. Slip fit usually turns solid in less than 10 seconds so beware.
                Give little extra heat(100c or so) it's ready for action after parts have cooled down.
                PERFECT! That would put the 638 into the almost instant use options then.

                Wdtom, you also raise a good point about the need for a vent hole or perhaps a slight flat along the drill shank to let the excess glue exit for a better overall fill.
                Chilliwack BC, Canada

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                • #23
                  Originally posted by Tundra Twin Track View Post

                  Good idea with the shrink fit,will try that why do you machine the shaft away after installed?
                  I couldn't pull the shaft off the drill bit after I was done with it - even with some heat, so I machined off the part of the shaft that was holding the bit.

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                  • #24
                    Originally posted by kev74 View Post

                    I couldn't pull the shaft off the drill bit after I was done with it - even with some heat, so I machined off the part of the shaft that was holding the bit.
                    I was thinking you would leave it intact for the next job🙂

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                    • #25
                      The only useful thing I've done with my acetylene rig in the past decade was silver solder drills and other cutters into pieces of DOM
                      -paul

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