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cutting keyway on lathe

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  • cutting keyway on lathe

    i have a hard time centering the keyway properly when cutting it on my lathe i always seem to end up with a slight angle .. what is the best way to center the cutter to make the keyway accurate .. ? i could use a little help thanks jack

  • #2
    Keyway on lathe

    What does your setup look like?
    Kansas City area

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    • #3
      Are you using a milling attachment?

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      • #4
        Perhaps I misunderstand. Are you talking about cutting an external key way on a shaft or an internal key way?

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        • #5
          For external keyways on a shaft I built the fixture shown in this video. It also works well for drilling cross holes through round stock. I like the way it uses the lathe itself to align everything.

          http://www.youtube.com/watch?feature...&v=eVgZol6Mfvo

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          • #6
            What I do to center the shaft and with the lathe turning I bring the shaft up to the cutter just so it barely rubs the shaft and makes a mark. That mark is the high point of the shaft and should be centered. Then move the shaft so the mark is perfectly centered under the cutter and go to town.





            Andy

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            • #7
              http://www.youtube.com/watch?v=vVUK-...3&feature=plcp
              Mike

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              • #8
                Confusing to follow when the axis names (XYZ) are mixed and not as they should be. Otherwise very informative and nice
                Amount of experience is in direct proportion to the value of broken equipment.

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                • #9
                  sorry about that i am talking about an inside keyway as in a pulley and such i always seem to be slightly angled as to the center because i am not dead center with the cutter hope that makes sense . thanks

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                  • #10
                    Originally posted by vpt
                    What I do to center the shaft and with the lathe turning I bring the shaft up to the cutter just so it barely rubs the shaft and makes a mark. That mark is the high point of the shaft and should be centered. Then move the shaft so the mark is perfectly centered under the cutter and go to town.





                    thanks for the tip that will help me for sure jack

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                    • #11
                      Originally posted by Toolguy
                      What does your setup look like?
                      i put the pulley in the chuck and the cutter on a boring bar , then i gradually make the cut using the carriage feed . in a few thou increments , works ok except for the alignment . as i said jack

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                      • #12
                        Noob answer so it may not be the best or even work at all.

                        If the tool bit has a "square" edge and the very first cut is not on center, will not one edge/corner of the tool cut and the other will not...I am explaining this poorly but the bore is round and if the cutting edge does not make even contact on the interior at the "apex" (misnomer as there is no real "apex") only one corner of the bit will actually be cutting (you would have to barely make contact...)...adjust up or down as needed to center

                        the only other way I can think of is to have a center on center in a tool post holder and "scratch" the mid-line of the pulley or gear and then center the tool bit on that mark

                        indicate edges of bore and center accordingly?

                        Edit: depending on how accurately you can measure, and its similar to the first method I posted, you could use the shank end of a drill bit somewhat smaller than the bore, put it in a tool holder and advance the cross feed...at some point the edge of that shank will contact the edge of the bore, you then note the relative point of the cross feed dial (or reading on DRO), if you think it is not centered, raise or lower the tool holder and contact the edge again, make note of the dial or DRO reading and compare the two numbers, you will now know if you moved further up or down from the center...the true center will be the maximum reading you can get (for a given bore) [not sure if my thinking is correct but all you are doing is finding an internal center so any centering method should work]
                        Last edited by RussZHC; 01-01-2012, 09:40 AM.

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                        • #13
                          Ahh, internal keyways. I still use a hacksaw or sawzal for those. lol

                          I would love to get a broach for doing them!

                          Jack I would suggest a broach unless you really want to use the lathe for this.

                          Andy

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                          • #14
                            Originally posted by Jaakko Fagerlund
                            Confusing to follow when the axis names (XYZ) are mixed and not as they should be. Otherwise very informative and nice
                            (XYZ) is correct for a mill. X left-right, Y front-back, Z up-down.

                            For a lathe (XZ). X feed of tool into and away from the centerline of the lathe. Z is feed parallel to the centerline of the lathe.

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                            • #15
                              Originally posted by jack3140
                              sorry about that i am talking about an inside keyway as in a pulley and such i always seem to be slightly angled as to the center because i am not dead center with the cutter hope that makes sense . thanks

                              I don't know if it will help, but I posted this a while back.

                              http://bbs.homeshopmachinist.net/sho...nternal+keyway

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