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Cutting Internal Slot

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  • Cutting Internal Slot

    Newbie question. I need to cut a new internal slot on a pulley and haven't a clue how to do so. Any reference would be greatly appreciated, or some step by step instructions. Thanks for your help. Ron in Central New York

  • #2
    There are a number of ways to cut an internal keyway. A fine big old vertical slotter would be just the thing for the job, but you don't likely have access to one of those!

    Could also be done on a shaper. If you don't have one of those, it can be done on a lathe.

    Another option (and probably the easiest) is to cut it with a broach.

    Let us know what you have (or have access to) for machinery and maybe the dimensions of the pulley and we'll be able to give you more specific advice.


    [This message has been edited by Herb W (edited 11-01-2002).]


    • #3
      This question got a pretty thorough airing several months ago, with quite a few suggestions for people without the right tool for the job. Try searching in the archives.


      • #4
        Try cutting a groove with a round rat tail file that is smaller that the dimensions of the key. When you get it to the proper depth, square off the sides with a Warding File or a small triangular file that you have ground the teeth off one side to make it "safe".


        • #5
          ...or remove the initial bulk of the metal with an end mill slightly smaller than the final slot width you want, then do the filing to square up the corners and bring to final width.
          It helps a lot to have the correct file(s), by the way. Worth the investment.

          Try to make a living, not a killing. -- Utah Phillips
          Don't believe everything you know. -- Bumper sticker
          Everybody is ignorant, only on different subjects. -- Will Rogers
          There are lots of people who mistake their imagination for their memory. - Josh Billings
          Law of Logical Argument - Anything is possible if you don't know what you are talking about.
          Don't own anything you have to feed or paint. - Hood River Blackie


          • #6
            & now for the easy way - turn a plug of the same material as the pulley to a light push fit in the hole, now drill a hole slightly less than key width in diameter on the joint line. Remove plug, the resulting 'half moon' is very easy to file square.

            [This message has been edited by Tel (edited 11-01-2002).]


            • #7
              Tel, that's brilliant. Falls in the category of .."why didn't I think of that!"
              Lynn (Huntsville, AL)


              • #8
                BY GOLLY TEL!!!!!! thats neat!. I have cut slots free hand with a small home made chisel. But youres is a good idea, don't even have to turn a plug, use an old bolt and drill. or piece of shafting. maybe heat a piece of key stock to critical temp, cool slow, make a cutting shape, reheat, quench and temper and drive it through. Takes longer to wirite it than to do it (maybe i exaggerate a little). Damn sure faster than writing it and correcting my speeling

                (EDIT COMMENT- lynn said it fast while i was composing!!- look at the times)

                [This message has been edited by docsteve66 (edited 11-01-2002).]


                • #9
                  Why not just place your pulley on the shaft and drill into it to make a round key instead of a square one? Believe it or not, the round keyway is stronger than the square one, as are all radius features. Drill, ream if you want, tap in properly sized round stock, you're done.


                  • #10
                    You sure are a smart bunch of folks!


                    • #11
                      what's a broach


                      • #12
                        You know what they say about a picture!


                        • #13
                          Even after removing the round keys on my Southbend lathe handles I still never thought of using a round keyway on my power transfer projects...I guess just because most of the shafts/pulley/gears I want to mate to already have a square keyway so I boxed myself into that thinking. Why are square keyways so prevalent?


                          • #14
                            .. for one thing, the square key offers a good seat for a grub screw.

                            As far as the little winkle of drilling the hole goes - it also does the trick on new work - mark the centre of your hole, scribe the circumference & then a pop mark on that is where you drill a slightly - key size hole before boring your shaft hole. Just one o' them things I thought everybody did.

                            [This message has been edited by Tel (edited 11-02-2002).]


                            • #15
                              Tel, You hit on a touchy point there. I think we all do some clever things, never mention them cause we either figure every one else must have known the trick long before 'we learned the trick OR we figure its is so simple that others would think they were being insulted by being told.

                              I have learned a lot here. Thanks to the newbies who have the self confidnece to to ask and the experieinced folks who adress the kids and INFORM old codgers such as I.

                              So to both the ignorant and educated, THANKS A LOT!!!!! and merry Christmas, little Tim.