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  • slotting on a lathe

    I want to do a keyway in a bush on my lathe . I have done a pulley in aluminium before but this time its in steel. How do I get my 4mm slotting tool to be at center height.I an only think of eye balling it. What is the correct way.

    I thought this was quite clever.
    https://www.youtube.com/watch?v=xmfw1phGV90
    Last edited by plunger; 09-02-2017, 03:25 PM.

  • #2
    I did that on my little 8x14 lathe for cutting a keyway for a new carriage handwheel


    Sent from my iPhone using Tapatalk Pro

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    • #3
      Originally posted by RB211 View Post
      I did that on my little 8x14 lathe for cutting a keyway for a new carriage handwheel


      Sent from my iPhone using Tapatalk Pro
      Was the tool solidly fixed to the plunger bar, or is it hinged like a shaper clapper box?

      I could really use such a slotting attachment on the SB9 here, maybe a smaller version with short stroke would suit my trike building.

      Thanks to Plunger and Merv for the video.

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      • #4
        I simply mounted the tool in the QCTP. The tool itself was a HSS bit I ground to have clearances on three sides. Forgot how I moved the carriage, must of used a wrench in place of the broken hand wheel


        Sent from my iPhone using Tapatalk Pro

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        • #5
          Originally posted by plunger View Post
          I want to do a keyway in a bush on my lathe . I have done a pulley in aluminium before but this time its in steel. How do I get my 4mm slotting tool to be at center height.I an only think of eye balling it. What is the correct way.

          I thought this was quite clever.
          https://www.youtube.com/watch?v=xmfw1phGV90
          MEASURE!

          Run any good bar in the lathe spindle. Chuck it if that is what is fitted (or you could use any tool fitted in the tailstock)

          Measure the diameter of your "test bar". Measure the distance between the bottom (or top) of the test bar and some surface on the cross slide. (or the bed for that matter)

          Add or subtract the test bar half diameter to or from the measurement.

          Mount your slotting tool.

          Measure from the lathe reference, and set the cutter at the calculated dimension, less the cutter width divided by two.

          I just did this about a week ago. It's not hard if you first make a sketch to fill out dimensions on.
          The work piece I was into was 3/4 bore, 2 inches in length to fit a 1/4" full length key.
          .0015 Depth of cut (per pass, and it takes two or more.
          Took most of an afternoon, but the fit is very good,and should drive the snow blower for a LONG LONG TIME. ;-)

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          • #6
            Depth mic down from known diameter to top of cutter.

            You may have some problems in steel. Try cutting a smaller keyway first, then following full width.

            metalmagpie

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            • #7
              I have three 1/8" keyways, less than 1/8" deep to produce in 3/4" diameter by 1/2" deep holes in a fairly soft steel. Most of the kit shown is too involved for just three, with very little likelihood of repeat use.
              I was hoping to make up something using, say a 3mm parting tool tip such as an MGMN 300 cut in half or a small piece of HSS if I can find a bit in my junk. Put it in the tool post and simply use the saddle to provide the tool stroke. Or use the mill quill to do it. What do you think?

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              • #8
                Originally posted by old mart View Post
                I have three 1/8" keyways, less than 1/8" deep to produce in 3/4" diameter by 1/2" deep holes in a fairly soft steel. Most of the kit shown is too involved for just three, with very little likelihood of repeat use.
                I was hoping to make up something using, say a 3mm parting tool tip such as an MGMN 300 cut in half or a small piece of HSS if I can find a bit in my junk. Put it in the tool post and simply use the saddle to provide the tool stroke. Or use the mill quill to do it. What do you think?
                Yes!

                Use a boring bar to hold a HSS tool ground to suit. The tool bit get's small and clearances are tough in a 3/4 inch bore. ;-)
                The saddle motion is enough, just make the cuts to match the stiffness of your lathe and set up.

                Anything you can do to "rough out" the waste is to your advantage. time wise One dodge is a close fitting plug, turned up to fit in the bore. Then a common twist drill is used to drill down through at the interface. This produces a "half hole" in each part, removing the lion's share of the metal. The half hole in the work is easily brought to final form with the single point broach. Careful work with a safe file could likely do the clean up as well. The plug can be used to produce a number of "half holes". Certainly three.

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                • #9
                  I have sucessfully managed to do this keyway. It took me about three hours to grind a form tool and set the job up and about 15 minutes to do the broaching.
                  I was taking off about 0.05mm at a time but would have to do two strokes at times. You can feel when its done as there is less drag. I think there is spring in my boring bar.
                  This is in a 12mm hole. I did the slot on the far side of of the lathe so I could see my progress.
                  My lathe has a permanent gap so I couldnt use the carriage. Most of the time was spent in setting up a handle for using my top slide. I have made it before I just had to figure how to set it up.
                  It really works well .Just a time consuming process. It makes me wonder how difficult it would be to make a broach out of guage plate .

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                  • #10
                    I am battling to send photos since the demise of hotobucket.
                    [IMG][/IMG]

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                    • #11
                      The handle before bending
                      [IMG][/IMG]

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                      • #12
                        This is what its for.
                        https://imgur.com/CuIgrBR

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                        • #13
                          The simplest method is to use a boring bar, AND cut horizontally. Grind the HSS tool to size, "keystoning" it for clearance. You can adjust up the holder, or shim under a solid holder, to center the cutter, then adjust crosslide to get depth.

                          It's very hard on lightweight lathes, and can break an Atlas, the feedwheel zamac casting on many Atlas machines may not take the force. OK on bronze or aluminum, I do not like to do it on steel or cast iron even.

                          A lever feed may take the force through in a better way.
                          1601

                          Keep eye on ball.
                          Hashim Khan

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