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cincinatti gear holder attachment; how does it work

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  • cincinatti gear holder attachment; how does it work

    What exactly is it used for?:


  • #2
    A complete description is in the Cincinnati Operators Book on page 29

    http://neme-s.org/Shaper%20Books/shaper_book_page.htm

    Errol Groff
    Errol Groff

    New England Model Engineering Society
    http://neme-s.org/

    YouTube channel: http://www.youtube.com/user/GroffErrol?feature=mhee

    Comment


    • #3
      I wasn't too happy with the appearance of the Operators Instruction Book and I recently found a nicer copy of that book so I will be re-scanning it. In the meantime I did the pages related to the Gear Cutter Grinding Atachment which is what you asked about.

      The attachment is NOT for grinding gears It is for grinding the GEAR CUTTERS.

      http://neme-s.org/Shaper%20Books/Cin...ool%20Grinder/

      You want the file titled: Gear Cutter Grinding

      Errol Groff
      Errol Groff

      New England Model Engineering Society
      http://neme-s.org/

      YouTube channel: http://www.youtube.com/user/GroffErrol?feature=mhee

      Comment


      • #4
        A toothy grin (or grimace)?

        Errol.

        That was a great link.

        http://neme-s.org/Shaper%20Books/Cin...ool%20Grinder/

        It is the only time I've see mention from a credible source that gear cutters can be ground with other that a radial face with no back or side rake.

        I've been going to mention it several times but given how definite some people were (are?) about it, I just gave it away.

        When cutting gears in other that brass or cast iron - which are pretty soft and which "like" zero rakes, I always had to use cutters that had either or both back and side rakes as it made for cleaner cuts with a lot less "hammering" - for much the same reasons as apply to "staggered" side and face cutters and tee-slot cutters etc.

        5>10 degrees of back rake won't alter the tooth form all that much and won't matter most times.

        We usually ground the back rake (0>5>10 degrees) as normal and then tilted either the job or the wheel and hand-formed it until it blended smoothly at the cutting edges.

        It worked very well on horizontal mills that were well-suppurated by the bearing brackets but it worked even better on the vertical mills (which are a cantilever) to reduce the "hammering" and spring.

        I did like the advice to grind the reference faces on the back of a new cutter as the front face cannot (should not?) be used as a reference as the last tooth has a problem.

        We had to made indexers like this on from one of my T&G grinders:






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        • #5
          Tiffie -

          I assume that you are talking about form relieved gear cutters (Brown and Sharpe) type not hobs?

          Did you make the rake modifications on bought in cutter or were these cutters that you made yourself from scratch? In the latter case, you could compensate for the form modification made by the rake change, but the sums would get tricky.

          I'm a bit surprised that a 10 degree rake on a bought in cutter would produce an acceptable gear form, but I can see why you might want to do this. I think a bit of CAD investigation might be useful to see the result.
          Bill

          Comment


          • #6
            The re-scanned version of the Operators Instruction Book for the No 1 Tool and Cutter Grinder is uploaded.

            The new file (of the same information) is 13 meg versus the previous version which was 122 meg.

            http://neme-s.org/Shaper%20Books/Cin...ool%20Grinder/

            Excellent information on the grinding of tools and cutters!

            Thanks Oldtiffie for the kind words. You posted some great photos!

            Errol Groff
            Errol Groff

            New England Model Engineering Society
            http://neme-s.org/

            YouTube channel: http://www.youtube.com/user/GroffErrol?feature=mhee

            Comment


            • #7
              No probs

              Originally posted by willmac
              Tiffie -

              I assume that you are talking about form relieved gear cutters (Brown and Sharpe) type not hobs?

              Did you make the rake modifications on bought in cutter or were these cutters that you made yourself from scratch? In the latter case, you could compensate for the form modification made by the rake change, but the sums would get tricky.

              I'm a bit surprised that a 10 degree rake on a bought in cutter would produce an acceptable gear form, but I can see why you might want to do this. I think a bit of CAD investigation might be useful to see the result.
              Bill.

              10 degrees is at the extreme end of the range - at 5 degrees, the difference is negligible and can be "adjusted for" by setting mating gears at the correct centre distance and checking for "run", "feel" and back-lash/clearance.

              If needs be use these as "roughing/gashing" cutters and finish off with a cutter with 0>5 degree top rake and 5 degree alternating side rake.

              We had a profiling/copying (hydraulic) lathe which could work in 1 direction ("in/out") and 2 directions ("in/out" plus "left/right"). On jobs like making cutters it had a stylus/follower/tracer that followed a rotating cam which rotated at the number of teeth X the job/blank speed - ie one cycle per tooth. Left/right followed a pattern mounted on the back of the lathe. It was a predecessor of a CNC lathe.

              Most of our better gears were made either on a horizontal mill and a hobbing cutter or on a gear shaper/hobber/generator.

              I don't get too fussed about gears generally in making them as its surprising how "forgiving" they are under load in service.

              Many who get so concerned about gear accuracy either don't care or don't look at the change gears, quick-change gear-boxes or under lathe aprons etc. - which just churn around year after year and not a problem.

              If I have a good gear to be made I send it out to a specialist with the machines and metrology required. But most times shop-made or store-bought gears do well enough.

              Comment


              • #8
                Tool heads

                Originally posted by Errol Groff
                The re-scanned version of the Operators Instruction Book for the No 1 Tool and Cutter Grinder is uploaded.

                The new file (of the same information) is 13 meg versus the previous version which was 122 meg.

                http://neme-s.org/Shaper%20Books/Cin...ool%20Grinder/

                Excellent information on the grinding of tools and cutters!

                Thanks Oldtiffie for the kind words. You posted some great photos!

                Errol Groff
                Many thanks Errol - glad to help.

                That adaptor can have 5C and ER-32 collets fitted as well which makes it very versatile. It can operate with a "free" spindle so as to act as a pretty good quill for grinding side and face cutters as well as end mill spiral edges. For "straight" teeth the finger/stylus can be on either the table or the saddle but on spiral teeth it is on the saddle and the quill rotated as the table is moved left-right - just as the Cincinnati T&C grinders used to do.

                The "tool-post" is ideal for grinding any angle on any cutter for lathe or a shaper, but I rarely use it as I always grind "off-hand" on the "grey" (so called) "emery" wheel on my pedestal grinder.

                Here is mine - again:


                and another from my other T&C grinder that is simpler to make and just as good in most cases:


                There are plenty of these about in the USA from what I'd heard ans seen here - cheap - and it will do most of the work too:


                and here is one that McGyver made - which will work just as well - I was amazed at just how well he did - and for the "smart-ar$es", he did clean up the welds, used some good filler and painted it and it looked very well - a credit to him:

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