Using a dividing head to make gears

Discussion in 'MACHINE ACCESSORIES' started by Nels, Apr 5, 2011.

  1. Nels

    Nels Founder Staff Member Administrator

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    Dividing Heads pretty much all work the same. If the main gear is 40:1 as most are. The Ellis & L&W manuals are available in our downloads area at http://hobby-machinist.com/index.php?action=downloads;cat=36. The plates often fit just one brand machine, But are easy to make or search ebay, the dimensions to fit are the bolt pattern, center hole diameter, pin hole dia.

    Plates are numbered 1,2,3 called low number plates will do most any common dividing, the 4,5,6 plate high number plates are for the higher dividing. There are still high prime numbers that need a different machine to accomplish.

    For example you need to make a 250 division dial, to do that you need a 25 hole plate, you don't have one, but you have a 15 hole plate, with a 15 plate you make the 25 plate, then use it to make a 250 division dial.


    Heres the plate hole counts for a 40:1 head.

    #
    1) 15, 16, 17, 18, 19, 20

    2) 21, 23, 27, 29, 31, 33

    3) 37, 39, 41, 43, 47, 49
    ***************

    The B&S one, which has somewhat smaller plates
    (largest number of holes is on the outside row):

    Plate #1 #2 #4
    Row == == ==
    Outer 20 33 49
    19 31 47
    18 29 43
    17 27 41
    16 23 39
    Inner 15 21 37

    The first plate is 20, 19, 18, 17, 16, 15.
    The second plate is 29, 28, 26, 21, 20, 16.
    The third plate is 61, 59, 49, 44, 39, 33.

     

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    Last edited by a moderator: Nov 30, 2011
  2. Conrad Hoffman

    Conrad Hoffman Iron

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    There are lots of spreadsheets and such out there for dividing heads- mine is in my threads and changegears spreadsheet located here.
     
  3. pjf134

    pjf134 Active User Active Member

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    Back in the 60's while I was taking a machine course at night I used a automatic gear maker. It had a lot of holes, like a QCGB has, you would put a blank in the holder and set the machine to the right pegs then turn on and walk away, then come back to a finished gear. Has anyone seen one of these? I can't remember too much about it being so long ago. I have never seen another one like it since. I do remember that you had to pick the right blank, O.D., I.D. maybe. I would like to see one like it, if they still make them. I guess a gear manufacture would have something like it.
    Paul
     
  4. BRIAN

    BRIAN Global Moderator Staff Member Supporter Active Member

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    David Thanks thats another thing on the wish list Number 964 I think.
    Until then I will have to keep twidleing the thing.

    Walter has a ace program for dividing in in his metal shop calc download.

    Regards Brian
     
  5. boodogboo

    boodogboo Active User Active Member

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    Thanks for all the info, I do have a good question, I have a PTO shaft that fits an old Gravely I need to make another one and I have never made one before, the shaft has 15 splines, dia. .985 o.d. aprox. and 6 1/2" long would a spin indexer do this job? and how do I find out what cutter to get?
     
  6. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    Spin indexers are not all that heavy duty, and lack a positive indexing means that you could use to establish the exact spline spacing, but there are ways to get around that. As far as a cutter goes, probably simplest to do this job with a 90° fly cutter and hand ground tool that matches the original profile. Use thread wires to measure the old one and the same wires to make the new one.
     
  7. boodogboo

    boodogboo Active User Active Member

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    That's kinda what I was thinking Tony, those things don't look all that great, so I should get a 4" rotary table divider combo with a 3 jaw chuck. Fly cutters work good for cutting splines? what kinda cutting tool should I use? any particular name brand? Thanks! Vernon
     
  8. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    Well Vernon, tell us a little about what kind of machinery you have to work with, first off. Second, and certainly no insult intended, how experienced are you? I ask that simply so we don't detail out too much information that you already know and makes you feel insulted. If you are a real beginner, on the other hand, we can give you every step as needed. Along the way, just ask for clarification if you feel that you need it.
     
  9. boodogboo

    boodogboo Active User Active Member

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    3yrs in high school 30 yrs ago and a little simple stuff along the way cutting keys, bushings that sort of stuff.

    - - - Updated - - -

    Oh I have a smithy 1324 max combo
     

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