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  • Dividing head problem...

    Hey guys...I'm bagged...been working on moving my Ohio mill into my too small machine room. Getting it set up for when my helper comes back so she can start learning how to cut gears.
    Had to tear the table off and move a million things about 4 times each ...moving engine hoist around and thru etc etc etc . I ended up with the mill sitting right beside the monster old dividing head I got with my VN. It's a Cincy head if i recall.
    Anyway I got monkeying around with it...it's a pretty cool old head.
    I need to cut a 10.82" gear with 204 teeth(6tpi).
    so..I've decided to do it with this old head.
    However..I'm lost with the calculations.
    I can follow the formulas easy enough for small gears but this big tooth count has my tired noodle all buggered up.
    The dividing head is a 40 to 1. The only plate on it has from 24 to 43 holes.
    How in the heck do I figure the right row on the plates...and how many hole spaces etc?
    I need one of them fancy Decimal to fraction calculators. I found an excellent program for that...I don't have the right calculator. What am I missing?
    I can figure out 33 or 28 or whatever...small gears...no problem...not this high tooth count..
    Thanks!
    Russ
    I have tools I don't even know I own...

  • #2
    Originally posted by torker
    Hey guys...I'm bagged...been working on moving my Ohio mill into my too small machine room. Getting it set up for when my helper comes back so she can start learning how to cut gears.
    Had to tear the table off and move a million things about 4 times each ...moving engine hoist around and thru etc etc etc . I ended up with the mill sitting right beside the monster old dividing head I got with my VN. It's a Cincy head if i recall.
    Anyway I got monkeying around with it...it's a pretty cool old head.
    I need to cut a 10.82" gear with 204 teeth(6tpi).
    so..I've decided to do it with this old head.
    However..I'm lost with the calculations.
    I can follow the formulas easy enough for small gears but this big tooth count has my tired noodle all buggered up.
    The dividing head is a 40 to 1. The only plate on it has from 24 to 43 holes.
    How in the heck do I figure the right row on the plates...and how many hole spaces etc?
    I need one of them fancy Decimal to fraction calculators. I found an excellent program for that...I don't have the right calculator. What am I missing?
    I can figure out 33 or 28 or whatever...small gears...no problem...not this high tooth count..
    Thanks!
    Russ
    Russ, I'm no help on the deviding head math.What helper You got coming back? The Girl, or Her Son or Your drill press slave-er Wife?

    Steve

    Comment


    • #3
      Yup...we're trying to find a place back in the shop for the gurl. She needs a second, part time deal...problem is...she's not interested in the things she used to do before she came to work here.
      She's hooked on chips!
      This whole thing is (hoping) going to be a kick in the arse for me...to get some cnc equipment in the shop finally.
      Nothing in stone yet...we both have a lot to learn..
      Russ
      I have tools I don't even know I own...

      Comment


      • #4
        Hi Russ,

        I figure you need a 51 division plate for plain indexing. With such a plate you would generate a tooth every 10 divisions (40/204 = 10/51). Thus you would generate 5.1 teeth per crank rotation, x 40 cranks =204 teeth.

        Time to make a plate?? Or can you do differential dividing with your head?

        Hope this helps.

        Comment


        • #5
          204 spaces on a Cincy head, you need a 51 hole plate, 10 holes per space. Cincinnati plates had a different set of holes than B&S, there wasn't a 51 hole circle on any of the B&S plates.

          Joe

          Comment


          • #6
            Can't seem to get edit to work, Pherdie's quicker than me.

            Joe

            Comment


            • #7
              I hope it works out for both of You. Russ I hope You know....that Monarch is not C N C .
              Good luck and all the best to both of you.

              Steve

              Comment


              • #8
                Now you have to make a plate with a 51 hole circle. Easy enough done a la Gingery and if you are careful quite accurate. If you have room between one of the circles or on the outside, half your work is done. Get a strip of paper, (not too thin), the width of the thickness of the plate and make it long enough to more than reach the circumference of the plate. Now wrap it around the plate, get it tight and use a razor knife and cut through where they overlap. Tape it to a sheet of drawing paper.mark a line along the middle of the strip. sharp pencil needed for this and subsiqent lines. Make a strip about 2" longer and mark a line along the middle of this one. Make a vertical line from the right end of the first strip. Use deviders and mark off 51 spaces along the second strip, experiment until you use up most or all of the length. Now mark off 51 spaces along the second strip ACCURATELY. Put a pin in the "0" of the long strip and the "0" of the main strip and swing the long strip up until it lines up with your vertical line. Drop verticals from each point to the circumference strip. When the strip is taped to your plate the cut line will be "0" and 51. Now you have to devise a method to line up each line with a pointer and drill your 51 circle. I do it in my lathe with a dremel in the toolpost and a pointer mounted on the headstock. Be sure the pointer is exactly on each line as you drill. I use a 1/8" center drill for this op and drill to the pin size after. I have made four plates this for my dividing head and you can't hear any variation when the gear is running at high speed. Long winded I know but it works if youre stuck, Good luck, Peter
                The difficult done right away. the impossible takes a little time.

                Comment


                • #9
                  ....or have a good buddy pop out a CAD generated 51 hole pattern for your size plate, e-mail you the pattern, print, paste the pattern on the plate and drill.

                  Comment


                  • #10
                    Take a piece of Aluminum Foil over to a Shop with a 51 Plate.

                    Set it on Plate and Rub just the 51 Circle... Or all of the Circles and Plates......

                    Get busy with a Centerpunch and Drill

                    Give Us the OD and ID of your existing Plate.

                    Make up a Couple Blank Plates...

                    My 2 Sets of Plates are ~ 5 1/8 OD and 4 7/8 OD Probably small for your Head tho...

                    Sorry for Wasted Frame size.I poked around and was able to enlarge it on Photobucket. Looks like this Image if blown up, is good enough...

                    53 51 49 47 46 hole Plate



                    You can go direct to Photobucket page to get in Full Res...
                    Last edited by Bguns; 01-16-2009, 03:53 AM.

                    Comment


                    • #11
                      The good buddy must know what diameter is available on Russ's plate.
                      The difficult done right away. the impossible takes a little time.

                      Comment


                      • #12
                        Look at the back side of the plate. A lot of Cincinatti dividing heads had double sided plates with different hole counts on each side.
                        Jim H.

                        Comment


                        • #13
                          I'll make you a plate Russ. What are the specs? Yeah, I know, 51 holes.
                          Free software for calculating bolt circles and similar: Click Here

                          Comment


                          • #14
                            Holy Smoke! Thanks guys!
                            Maybe I should tell you what I'm up to first...you may see a hole in my game.
                            I'm making a hillbilly worm gear to rotate my welding positioner.
                            I have an acme worm...it's 6tpi. About a 10 " gear will give me really good mechanical advantage. 6tpi yeilds the size of gear given previously.
                            I'm going to make this out of 1/2" plate...it won't be a full circle. I only need a bit more than 1/4 of the gear to get the head from verticle to horizontal.
                            This doesn't have to be perfect either...henceforth and dewwith..I've decided to set the helix angle for the worm with the dividing head set on the table at an angle (3*).
                            Then...LOL..after the gear was machined...I was going to grind an aproximation of the arc into the middle of the gear so it would more closely match the diameter of the worm. I know, I know...it may not work...but I will learn from my mistake...
                            So...it doesn't HAVE to be 204 teeth...
                            Russ
                            I have tools I don't even know I own...

                            Comment


                            • #15
                              Here is a pattern taken from the image above.

                              Free software for calculating bolt circles and similar: Click Here

                              Comment

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