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Cut my first gear today!

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  • Cut my first gear today!

    I cut my first spur gear today. A 32 DP 45 tooth .375 inch face spur gear. I would like to thank Marv Klotz for his utilities, Brian Rupnow for his help, and the rest of the forum for their gear/hob/cutter posts, all of which proved helpful. Images below (otherwise it didn't happen).

    My setup:


    Closeup:


    Final Result:


    - Tom

  • #2
    Congratulations! Someday I'm going to try that too.

    Comment


    • #3
      Yes, congrats from here also, looks great!! Thanks for the good pics.

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      • #4
        Very nice!
        Andy

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        • #5
          Nice - and congratulation to you. But here is some good advise for future production.
          It looks to me like you pushed a gear blank onto a tapered mandrel. If so, you are lucky the blank did not turn on you. That happens when the cutter pushes just a little bit one way or the other. Could be the sharpening or even run-out.
          Next time make a mandrel with a shoulder and a threaded part in front. Than tighten the blank on the mandrel using a nut. This will make sure there is no movement.
          Many times you don't even know the gear has moved. You can not see the difference on the tooth. But you will hear it once you assemble and run it. Happy gear cutting!

          Comment


          • #6
            Nice I too am going to try that someday. Where did you get the cutter. Was the cutter pushing the blank toward the big end?

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            • #7
              Good on you!!! Congratualtions,----Brian
              Brian Rupnow

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              • #8
                Tom, way to go, looks good

                Originally posted by Juergenwt View Post
                It looks to me like you pushed a gear blank onto a tapered mandrel. If so, you are lucky the blank did not turn on you. That happens when the cutter pushes just a little bit one way or the other. Could be the sharpening or even run-out.
                Next time make a mandrel with a shoulder and a threaded part in front. Than tighten the blank on the mandrel using a nut. This will make sure there is no movement.
                Many times you don't even know the gear has moved. You can not see the difference on the tooth. But you will hear it once you assemble and run it. Happy gear cutting!
                I hadn't heard this before, although use with a AL gear would give some pause is the soft material might deform. AFAIK, pressing a mandrel into a gear blank is fairly textbook as is working between centres, isn't it?
                .

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                • #9
                  Looks good to me too. I would also be concerned with possible movement on the mandrel. I agree with Juergen's suggestion.
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                  • #10
                    Very nice, you should be proud!
                    "Let me recommend the best medicine in the
                    world: a long journey, at a mild season, through a pleasant
                    country, in easy stages."
                    ~ James Madison

                    Comment


                    • #11
                      Cutting gears is enjoyable, cutting one that is the correct size is even more fun. The gear in the photo looks great. As to the means to hold them while cutting, the tapered arbor is worrisome as the smallest rotary movement and the gear is junk.

                      My personal preference is a stub arbor with either a screw or nut applying the clamping pressure. If possible I use a woodruff key to prevent rotary motion between the blank and the arbor. If the gear blank has a setscrew use that as well.

                      Sometimes a belt and suspenders are a good combination and if that isn't enough there is duct tape and super glue.

                      Comment


                      • #12
                        Shiny! I like it. Thanks for posting.

                        Comment


                        • #13
                          Cutting a gear by pressing the blank onto a mandrel is NOT the preferred method. However it will work fine if you are very careful and have a sharp cutter. The problem gets bigger if you have a larger dia. blank with a small dia. hole. That is why you have to make sure your blank can not move while being cut. Best of course is a blank with a hole having a key slot and a mandrel having a key. Set screw if you have a blank with a shoulder. The mandrel with a key requires a little more work. So the easiest thing to do is making a mandrel with a shoulder (the larger -the better) and a partially threaded front so you can tighten the blank against the shoulder using a nut. Centers on both sides are best but one could get away with using a chuck or a collet on the dividing head side. Use an indicator to make sure your mandrel is running true. Why take a chance and end up with a half of a tooth at the end. Bummer! Also make sure that you take out any play when advancing your dividing head spindle.
                          Another tip: If your mandrel is to long or to thin like is the case with MinnesotaHSM set up, and you are cutting a steel blank - the mandrel will be flexing on every turn your cutter makes - guarantied! Milling machine arbors do not run true and your cutter will be pushing down with every turn. At the end of the cut, when the cutter starts coming out of the blank, the cut will get slightly deeper. You will see it on your blank. That is why some people prefer to have enough material at the end of the cut so the cutter will always cut the full depth. You can turn it to size later. Next: always stop your cutter after finishing your cut before you crank back the table. Otherwise you end up with cutter marks on your blank.
                          Cutting gears can be fun and also a challenge. Lot of info in your MHB. You learn something new every time you make a gear. Happy cutting MinnesotaHSM. Juergen
                          Ps.: If you use a set screw be sure to check the blank for run-out after you tighten the set screw. They have a way of sometimes moving the blank or the mandrel.

                          Comment


                          • #14
                            Nice job.

                            Very nerve-wracking when you get to the second-to-last tooth and the space you have left looks all wrong, but then you get the last one cut and it's a perfect fit
                            Peter - novice home machinist, modern motorcycle enthusiast.

                            Denford Viceroy 280 Synchro (11 x 24)
                            Herbert 0V adapted to R8 by 'Sir John'.
                            Monarch 10EE 1942

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                            • #15
                              Tom,

                              Looks like a nice job. I also was in the process of setting up for gear cutting when other events in my life occurred. I can't wait to get back to that project.

                              Everybody,

                              I noticed the discussion on shifting of the gear during cutting and I can see those concerns. I was in the process of making a screw/nut style arbor as I think it is the best for this. But, the discussion does raise concerns about other details. First, I would think that it would be absolutely necessary to lock the dividing head or RT for each tooth. I do this with any kind of indexing work. I have been considering a hobing setup and wonder what, if any, precautions can be taken to prevent unwanted movement of the gear with such a setup. If you use a dividing head or RT, there will be some backlash and it seems that it would be possible for some random, reverse movement to occur.
                              Paul A.

                              Make it fit.
                              You can't win and there is a penalty for trying!

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