Loading ...
Sorry, an error occurred while loading the content.

Re: Cutting Tricky Gears

Expand Messages
  • ralph_pattersonus
    Yes, you have it correct. Good fishing...
    Message 1 of 11 , Aug 27, 2012
    • 0 Attachment
      Yes, you have it correct. Good fishing...


      --- In 7x10minilathe@yahoogroups.com, "Martin Thompson" <martin@...> wrote:
      >
      > Ralph,
      >
      > I very much appreciate your input... and the link to your library of useful mods.
      >
      > Is the "Spindle Indexer" in your library the spreadhseet that you mean when you write "Headstock Indexer" below? Sorry to be dumb!
      >
      > Martin
      >
      > --- In 7x10minilathe@yahoogroups.com, "ralph_pattersonus" <rpatter1@> wrote:
      > >
      > > Martin;
      > > when attempting to first cut gears for my Minilathe, I was too impatient to work out indexing wheels etc. I gave a try at indexing with a rotary table (vertical) clamped to the table of the Mill-Drill. To advance the RT between gear tooth spaces, I made an Excel spreadsheet to calculate stops for each cut. The spreadsheet has a cell to insert the drive ratio of the RT (72 in my case, in the attached reference 45 on the Headstock Indexer).
      > > http://www.toolsandmods.com/library/ralph-patterson
      > > (look half-way down on the right column of choices)
      > >
      > > This setup has worked so well that I never went on to use indexing plates as is normal with most shops. The formulas in the spreadsheet are based on making Mod-1 gears, where the pitch diameter of the gear is numerically equal to the tooth count. To make gears of Mod .5 it will be necessary to change the calculation box to divide by 2.
      > > To cut Aluminum gears it works well to grind a tool for use in a flycutter holder on the mill. Some experimentation is required to refine the cutter shape and symmetry.
      > >
      > > Good luck, and have fun at your project.
      > >
      > >
      > > --- In 7x10minilathe@yahoogroups.com, "Martin Thompson" <martin@> wrote:
      > > >
      > > >
      > > > Context:
      > > >
      > > > I am working on a project to build a spur gear device with 30+ gears,
      > > > driven directly by hand (via a crown wheel). The device only drives a
      > > > series of pointers, so there is no transfer of "power" through
      > > > the drive chain. Although it may look very much like a clock without a
      > > > spring or escapement, the gears will only get use when the device is
      > > > picked up and the handle is turned; wildest maximum use maybe around 30
      > > > minutes of rotation per year.
      > > >
      > > > I intend prototyping it in aluminium, before moving to 2mm brass for the
      > > > final device, cutting teeth with Module 0.5, 20 degree cutters. I have
      > > > been reading about the use of a dividing head for gear cutting.
      > > >
      > > > My Questions:
      > > >
      > > > * DIVIDING WHEELS: a few of the gears are LARGE; I need to cut 2
      > > > gears with 223 teeth (O.D. 112.5mm), plus 1 with 188 teeth and one with
      > > > 127. But will it be possible to find dividing wheels that will allow for
      > > > such a big prime numbers (223 & 127)? * CUTTERS: I am not concerned
      > > > at all about either backlash or gear wear for this application but only
      > > > with the regularity of division. This leads me to wonder if I could get
      > > > away with using a single Module 0.5 gear cutter to cut pinions from 15
      > > > teeth to spurs of 223 teeth, rather than purchase a full set of 8
      > > > cutters. Yes, I know that the teeth will not mesh properly, but it would
      > > > cost me £21 instead of £168. If so, which number cutter could I
      > > > get away with as a compromise?
      > > >
      > > > Many Thanks,
      > > >
      > > > Martin
      > > >
      > >
      >
    Your message has been successfully submitted and would be delivered to recipients shortly.