3/16 Square Motor Couplers

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  • mm123521
    Senior Member
    • Sep 2010
    • 150

    #1

    3/16 Square Motor Couplers

    Check out the square motor couplers I built.
    They are 5MM straight X .187" square.

    I built 4 square brooches to cut the square hole. Each one fits in the hole produced by the last one.
    They were ground out of high speed steel on a surface grinder then sharpened with a diamond file.

    These fit my Castle 1520 and 1518 motors. I have a pair of each for my Sprint Cat 40 build.

    Could'nt find anyone that sold these, so I made my own.
    I can build 5MM, 6MM, and 8MM versions of these if anyone needs one.

    Mark
    Attached Files
    Avatar is the dangerous end of a Gatling Gun!
  • LiPo Power
    DJI Drone Advanced Pilot
    • May 2009
    • 3186

    #2
    This is cool!!! How much?
    DJI Drone Advanced Pilot
    Canada

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    • mm123521
      Senior Member
      • Sep 2010
      • 150

      #3
      If you got a use for one , I'll make you a good deal.

      Mark
      Avatar is the dangerous end of a Gatling Gun!

      Comment

      • LiPo Power
        DJI Drone Advanced Pilot
        • May 2009
        • 3186

        #4
        Ok, how much would you charge for 8mm motor to 3/16 flex (with the hex key for screws, round ends, regular ends)?
        Thanks
        Robert
        DJI Drone Advanced Pilot
        Canada

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        • mm123521
          Senior Member
          • Sep 2010
          • 150

          #5
          Robert:

          You want 8MM X 3/16 round, with Setscrews to hold the 3/16 cable?

          Or

          8MM X 3/16 square ?

          PM me

          Mark
          Avatar is the dangerous end of a Gatling Gun!

          Comment

          • RaceMechaniX
            Fast Electric Addict!
            • Sep 2007
            • 2821

            #6
            Very nice work Mark,

            If you ever make 1/4" square drives for 8mm shafts, let me know.

            Tyler
            Tyler Garrard
            NAMBA 639/IMPBA 20525
            T-Hydro @ 142.94mph former WR

            Comment

            • mm123521
              Senior Member
              • Sep 2010
              • 150

              #7
              Tyler,

              I studied the dimensions and feasibility of cutting a 1/4 square without cutting into the 8MM end, it looks like it will work. It does not work for anything under 8MM.

              I worked out a 5 pass broach setup on paper, just need to build the broaches.

              What motor does this fit?
              How long is the motor shaft?
              Do you already have the motor?

              If you need one and can't purchase one (its always better to purchase than to custom build), then I can build it for you.

              Mark
              Last edited by mm123521; 12-29-2010, 05:57 PM.
              Avatar is the dangerous end of a Gatling Gun!

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              • RaceMechaniX
                Fast Electric Addict!
                • Sep 2007
                • 2821

                #8
                Hello Mark,

                Thanks for the offer, I looked at machining one myself as I have the 1/4" square broach, but for a single pass broach it does intersect the 8mm bore.

                I was thinking of using these on Neu 8mm motors and Lehner 8mm motors to get rid of the thrust on the motors. I do have both motors and all shaft dimensions.

                If you were interested in making these and selling them in quanities, I would be interested in buying several, but no point in just making a couple for me at this point.

                Here is a screen shot of the interference. It's an 8mm bore shown.

                Tyler
                Attached Files
                Tyler Garrard
                NAMBA 639/IMPBA 20525
                T-Hydro @ 142.94mph former WR

                Comment

                • mm123521
                  Senior Member
                  • Sep 2010
                  • 150

                  #9
                  Tyler:

                  What dimensions are you using for your model?

                  I measured a bunch of 1/4 drive flex shafts: .200 across the flats.
                  .200 across the flats times cosine of 45 degrees = .282 corrner to corrner.

                  I dont have the CAD at home, so I'am just using old fashioned trig.
                  I may be wrong on my math, but it looks like .282 goes right through the .315, 8MM hole. Thats a .033 clearance.

                  Are you using .250 across the flats? That would give you a .038 interference into the 8MM hole.

                  Mark
                  Avatar is the dangerous end of a Gatling Gun!

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                  • RaceMechaniX
                    Fast Electric Addict!
                    • Sep 2007
                    • 2821

                    #10
                    Mark,

                    I am using a true 0.250" across the flats in the CAD model. I will measure some of my flex shafts this afternoon to verify the actual sqaure dimension. I'll post my findings later on today.

                    Tyler
                    Tyler Garrard
                    NAMBA 639/IMPBA 20525
                    T-Hydro @ 142.94mph former WR

                    Comment

                    • mm123521
                      Senior Member
                      • Sep 2010
                      • 150

                      #11
                      Tyler
                      OK, that would help.
                      All of my 1/4 inch cables are X weed wacker drive cables.
                      Some are just a little under .200 across the flats and some are just a little over .200. It would be good to measure a bunch of cables to get an idea of what the tolerances are.
                      I have roughed out the first 3 of 5 broaches. I am going ahead with building the broaches, just in case someone needs one and I love making stuff, especially unusual tools.

                      Will you get me accurate dimensions on shaft length and diameter for the motors you mentioned?, if its not too much trouble, Please.

                      Mark
                      Avatar is the dangerous end of a Gatling Gun!

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                      • RaceMechaniX
                        Fast Electric Addict!
                        • Sep 2007
                        • 2821

                        #12
                        Mark,

                        I checked about 8 shafts and they are within .195" to .200". For both Lehners are Neu's the shaft measure 7.98mm to 7.99mm with a length of 22.15mm long from bearing to end.

                        If you need any more dims, just let me know.

                        Tyler
                        Tyler Garrard
                        NAMBA 639/IMPBA 20525
                        T-Hydro @ 142.94mph former WR

                        Comment

                        • mm123521
                          Senior Member
                          • Sep 2010
                          • 150

                          #13
                          Tyler:

                          Thanks for the help!

                          Mark
                          Avatar is the dangerous end of a Gatling Gun!

                          Comment

                          • RaceMechaniX
                            Fast Electric Addict!
                            • Sep 2007
                            • 2821

                            #14
                            Mark,

                            I could use two or three when ready. No rush though.

                            Tyler
                            Tyler Garrard
                            NAMBA 639/IMPBA 20525
                            T-Hydro @ 142.94mph former WR

                            Comment

                            • mm123521
                              Senior Member
                              • Sep 2010
                              • 150

                              #15
                              Tyler:

                              OK, I got the 1/4 flex cable broaches finished.
                              I built the finish cut broach a little tight -- .198 across the flats.
                              They require a touch with a needle file if you have a "fat" cable.
                              If thats OK, I can fix you up.

                              Concentricity looks good.
                              I have a reamer for .3155, so the 8MM end will be .0005 oversize.

                              Mark
                              Attached Files
                              Avatar is the dangerous end of a Gatling Gun!

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