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Thread: One step closer...

  1. #1
    Craftsman
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    One step closer...

    One day I intend to make a watch.
    Iím still a long way off, but tonight I made a good step in the right direction :)

    A large part of a timepiece is of course the wheels and pinions. Iíve been contemplating how to cut them without bankrupting myself buying the cutters.

    The Sunderland gear planer uses a fairly simple cutter for racks, and generates the curves of the spur gears by coordinating the cutting and a rotation, so the gear blank rolls against the rack as though it already had th teeth.

    I have several old engineering texts with some of the relevant details in:



    Of course I donít have a gear planer, and generally they are for much larger gears, but I can use the technique with a little bit of lateral thinking.

    First make a rack form cutter, simple lathe work.



    Then wack it into an indexer on the mill



    And create some flutes for the cutting edges.



    Then handily I have recently bought a kiln (for enamel) which I can use to Heat treat. So much easier than a blowtorch.



    I decided to keep the tooth count smallish for my first gear - 30 teeth /12degrees each. That also means I can use the simple divider. To assist my little brain I wrote down all the teeth angles so I could tick them off as I go.



    Then itís a question of put on the right cut and index /cut / repeat...



    Once the first pass is done I rotated the indexer by 6 degrees, moved the cutter by an equivalent linear amount and cut it again. This generates the tooth curves.

    The end result is gear shaped:



    And meshes with another 48dp gear nicely.



    I got a beautiful pattern when parting the gear blank off the stub it was machined as part of.



    There is more work to do, but I think the method will work without too much effort.

    Dave

  2. #2
    Grand Master magirus's Avatar
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    Great work Dave! Look forward to future progress. Meanwhile, that Porsche . . . ;-)

  3. #3
    Journeyman
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    Great work. Thanks for sharing....and keep us posted on the rest of your "journey".

    Sent from my G8441 using TZ-UK mobile app

  4. #4
    Craftsman
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    Had to make another cutter as the first one is too short to make a 144 tooth gear.
    I printed out the 144 tooth gear to compare the lengths and clearance with:



    Then I milled some flutes and a bit more clearance on the shank.



    Bit of a heat treat and I knocked some steel into the shape of a pinion.



    Then I whacked the bar into the Lathe and proceeded to put a hole in the middle and part off a few pinions for closer examination.



    They need a good debur (I need to sort a better parting tool I think) but the tooth form is quite reasonable.


    Dave

  5. #5
    Grand Master magirus's Avatar
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    Good to see some some progress Dave, keep at it!

  6. #6
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    Dave - can't believe there havent been more comments on this... epic work! I'd love to see a few videos of the milling and lathe processes. If you ever get a chance to record them and upload them to YouTube it would be great! Looking forward to future updates!

  7. #7
    Craftsman
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    Ive made some wheels.
    First trepan out some blanks, which avoids making loads of swarf just to get a roughly right sized blank.



    2 cut out without a hitch Happy face :)



    Because they are only roughly the right diameter I made a stack of Gage Blocks to allow me to size them to within a very small tolerance




    Turn to correct outer diameter in the lathe, whilst on the arbour they will get gear cut on.



    Cut some teeth


    And repeat x144. Took less time than you might think



    Now the blanks have teeth its time to give them some spokes.
    so I marked out 3 spokes:


    cutting a long thin slot is fraught, and usually ends up with a broken tiny endmill, so I went the easy route and chain drilled out the scrap.





    Then some filing to clean up the drill half holes



    And a pair of wheels is done enough to make the next bit.


    Ill do 'proper' finishing when the rest of the movement is more complete.

    I'm learning quite a lot about things that will help when I get to watch sizes, although I'm still not doing any work on the Porsche...

    Dave

  8. #8
    Master Webwatchmaker's Avatar
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    Well I think you're bonkers Dave S !
    In an eccentric way of course.
    I think you have to be to make a watch by hand.
    I think of people like George Daniels, Kari Voutileinen, the late Derek Pratt and of course AL Breguet. I know how much work making even one part can be and wish you all success.

    Sent from my SM-G900F using Tapatalk

  9. #9
    Grand Master magirus's Avatar
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    Great stuff Dave! Now, about that Porsche . . . ;-)

  10. #10
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    Brendan, Iíll take that as a complement :)
    I have to make a couple of timepieces - one for each child...
    New book on gears on order - these are involute tooth form rather than the traditional cycloid form, but I havenít yet found a complete set of writings which have convinced the engineer in me that involute really is a no no.

    Dave

  11. #11
    Master Webwatchmaker's Avatar
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    Quote Originally Posted by Dave S View Post
    Brendan, Iíll take that as a complement :)
    I have to make a couple of timepieces - one for each child...
    New book on gears on order - these are involute tooth form rather than the traditional cycloid form, but I havenít yet found a complete set of writings which have convinced the engineer in me that involute really is a no no.

    Dave
    Of course it's a compliment !
    Such skill and patience is required.
    It's a while since I made a wheel !
    From what I remember the involute gear form is used by most heavy industries, gearboxes etc, and will work well in both directions but sometimes require lubrication.
    With cyclical gears there is less friction but depth is more critical and devices turn best in only one direction due to tooth contact interfaces.
    *You've got to make three ! I want one too.

    Sent from my SM-G900F using Tapatalk

  12. #12
    Great story with some lovely machining

    Well done that man

  13. #13
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    Bit more progress, so a quick update.
    I hacked out a couple of more wheel blanks, this time for 96 and 90 tooth wheels.



    Then bunged them in in the mill and cut some teeth in the same manner as for the 144 tooth wheels, of course cut one at a time, as they have different tooth counts...





    Now I have 4 wheels, the smaller 2 of which need crossing out for spokes:



    The layout for the hands will be in a classic Regulator style - Large central minutes, with smaller hours and seconds, similar to this picture stolen form the internet:



    So the wheels end up laid out something like this:



    The hours are on the lower large 144 wheel, the minutes on the middle wheel, and the seconds end up on the escape wheel shaft.

    The steel for the pinions and shafts has appeared, so I'll be cutting them shortly, along with escape wheel and then plates.

    I've also got some reading material, about 1/2 way through it so far. Lots of maths and formulas, so needs to be read with attention.



    Dave

  14. #14
    Grand Master magirus's Avatar
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    Love the technical jargon Dave, "hacked" and "bunged"! Good to see more progress.

  15. #15
    Soon you will be able to build one of these??


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