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Cutting hypoid gears

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  • Cutting hypoid gears

    Has anyone ever had any experience cutting hypoid gears in the home shop? I have an article in my old Live Steam magazines by Kozo Hiroaka on how to cut skew bevel gears. The reason I ask is because I saw a short video on Youtube that showed a fellow cutting what I assume was a hypoid gear with some type of compounding attachment for a lathe.
    I am planning the next stage in my 302 engine, T-5 transmission project by making a scale 9 inch Ford differential.
    Thanks,
    gbritnell


  • #2
    There have been some videos of 'home' setups which the contributor claimed were for cutting hypoid gears. I have not yet seen one that would produce a correct hypoid or even a reasonable approximation. The contributors did not understand what the generating process for a hypoid actually looks like. This is an example. https://www.youtube.com/watch?v=8aUQM-VtElo
    I don't recall one using a lathe attachment and I can't find it on Youtube, so maybe that setup does work, but I am doubtful.

    I think that doing this properly will be a very big challenge indeed, but if anyone can do it it will be you! I would start by seeing if you could make something that mimics the way a Gleason hypoid cutter works. It might be possible to simplify this enough to make it feasible, but I haven't thought this through at all. I suspect that there would be as much work involved in that as your original engine project, but if successful you would have established a method that others would certainly want to follow. I for one hope that you have a go at this and will be watching progress with a lot of interest.
    Bill

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    • #3
      My first real job after Engineering school was production foreman in the hypoid gear department at GM Cadillac Motor Car in Detroit. If you have ever seen the compound action of a Gleason Hypoid generator as it rolls both the gear blank and cutter you pretty much would give up on trying recreate that action on your own. To the best of my knowledge ,The Gleason Works in Rochester NY remains the only source for these machines in the world. I think that the gear being cut in u-tube video is a spirial bevel gear.
      Joe B

      PS, beautiful work on the engine and transmission !!

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      • #4
        I think there are other makers of hypoid gear cutters these days, but the Gleason process is certainly going to be the most accessible in the US at least. My experience was something like JoeCB's, but Chrysler rather than GM. I had a look for a Gleason machine making a crown wheel. This one is short, but it does give you an impression of the generating action:
        https://www.youtube.com/watch?v=8wpZJ75g3Wo This is going to be really tough to replicate, but I wouldn't give up on this project for several reasons:

        1: I think that a less general machine than the Gleason could be made in small scale. There are a number of different settings and capabilities that you wouldn't need if you aimed at producing just one size of gear.

        2: The Gleason machines that I am familiar with were totally mechanical and complex. I think you could eliminate a lot of that complexity with direct drives and some electronics to synchronise rotations.

        3: You are presumably looking at a producing a hypoid gear set that works in the sense that it transmits rotation. Noise, life, efficiency etc are not a concern. This means that you can get away with a result that would be totally unacceptable in automotive production, where they would be expected to be near silent about as efficient as theoretically possible and have a lifetime under the worst possible conditions that should exceed the rest of the vehicle. That means you could take some liberties.

        Having said all that it is still a massive undertaking - just making a cutter (on the left in the video) that would work would be truly amazing.
        Bill

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        • #5
          Thanks, now my head hurts when I looked at those Gleasons making hypoid gears and just trying to picture it in my mind...
          Amount of experience is in direct proportion to the value of broken equipment.

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          • #6
            Just off the top of my head.... Possibly having the gear blank mounted on an indexer, attached to a pair of ROTABS, one on top of the other, would generate a hypoid gear pattern. Adding CNC controls would prevent a nervous breakdown or going crazy on the part of the operator.
            I've seen a similar setup to cut turbine blades.
            No good deed goes unpunished.

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            • #7
              Instead of making one, how about repurposing the spiral bevel gearset from an angle grinder? they are about 3.5:1

              allan

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              • #8
                Probably because with a hypoid gear set the axis of the pinion does not intersect the axis of the gear. Whereas it does with a spiral bevel gear set. Presumably the prototype that is being modelled requires that specific feature.
                Location- Rugby, Warwickshire. UK

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                • #9
                  Spiral bevels would be a bit easier. The problem is that for a proper old fashioned back axle you need hypoid gears. The difference between the two would be obvious at a glance from the appearance of the back axle casing. Now if you were making a front wheel drive transmission it would be a different matter, but the gearbox already built is obviously intended for a conventional rear wheel drive back axle, and given that it is a traditional American power train that would almost certainly be a live axle.
                  Bill

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                  • #10
                    Is there any where that the gear train calculations can be found as that looks very useful , I often have to buy (big$) little gears for pump or tacho drives , making your own would be cheaper and often quicker.
                    Michael

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                    • #11
                      Originally posted by mike4 View Post
                      Is there any where that the gear train calculations can be found as that looks very useful , I often have to buy (big$) little gears for pump or tacho drives , making your own would be cheaper and often quicker.
                      Michael
                      Yes, Gleason has lots of documentation and work sheets and software that you use to design a hypoid gear set and set up the machines. Having said that, you probably would not make any progress with them unless you were a real gear guru and in addition had some specific training. Even then, you would probably need support from Gleason or Klingelnberg or whoever's systems you were using. Then you would need the cutters for your gear; I'm not sure how you would even start on that. This is not a trivial exercise and nothing like setting up to cut an ordinary spur gear.
                      Bill

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                      • #12
                        The gear train in the video where the guy was cutting gears similar to pinions was what I was asking about , difficult maybe impossible not.
                        People managed to cut reasonable gears on manual machines before CNC and specially designed tools , so what if it takes a bit of time to set up , may be quicker than three months from an overseas manufacturer who asks over $400 for a 30mm dia gear with a slight taper .

                        The more that someone treats another as an untrained hobbyist the more determined I become.
                        Michael

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                        • #13
                          Originally posted by willmac View Post
                          ... you probably would not make any progress with them unless you were a real gear guru and in addition had some specific training. Even then, you would probably need support from Gleason or Klingelnberg or whoever's systems you were using. Then you would need the cutters for your gear; I'm not sure how you would even start on that. This is not a trivial exercise and nothing like setting up to cut an ordinary spur gear.
                          "Piffle !!!
                          Gimme a screwdriver and a hacksaw 'n get ready fer some learnin'."
                          -Granpa

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                          • #14
                            The first video was the method that I was interested in (https://www.youtube.com/watch?v=8aUQM-VtElo ) that showed the type of set that I am very interested in , Manual and done in a normal shop.
                            The only difference would be my finished products would be hollow.
                            Michael

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                            • #15
                              If power transmission and silent operation at high speeds are not requirements, perhaps a method could be worked out where each tooth space were cut with just two, three, or four different settings instead of the precise, continuous generation action of the Gleason machines. This would be somewhat similar to generating a bevel gear, which has a constantly changing cross section, with a single pitch cutter by using it at two different angles. The bevel gears produced this way are not ideal, but they could work and the model would be animated. Likewise, a less than perfect "hypoid" may be possible.

                              Since this would utilize several static setups to produce each tooth instead of the continuous generating action of the Gleason, the cutter could be made with a single insert instead of many. This would simplify the design of that cutter. Of course, the cutting process would take quite a lot of time with multiple passes for each tooth.

                              Just a thought.

                              Another thought: Perhaps it may be possible to make multiple generations of each gear in the set. Start with the smaller (pinion?) and generate it as best as possible using the above method. Then convert that gear into a cutter (by gashing and relieving it) to cut the larger ring gear by driving them at the final speed ratio (like a hobbing setup) and bringing them slowly together. The figure of the large gear would be better than that of the small cutter due to averaging effects. Then reverse the procedure and convert the large one to a cutter and generate a second generation small gear. Continue for several generations until no further improvement is achieved. Use the last two tools generated in this manner to cut your actual, final gears.

                              Again, just a thought. I have no evidence that the figure of each generation would actually be better than the previous. But it seems to me that it would. Yes, I know this would be a very laborious process but so would any other that you may attempt.
                              Paul A.
                              SE Texas

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

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