Building Parslow's Skeleton Clock by C. Raynerd

Discussion in 'Clock Construction' started by Raynerd, Feb 12, 2013.

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  1. Raynerd

    Raynerd Registered User

    Apr 11, 2004
    Teacher of Chemistry
    Manchester - UK
    Country Flag:
    Good evening.
    Just a brief update on my latest project after finishing Dr Woodward gearless clock last year (build log posted somewhere on these forums)

    This is Parslows skeleton clock. My aim, as with the gearless clock, is to build it all from bar stock. I've never cut a pinion and so much effort has gone into preparing for this. I also wish to cut my own cutters and so some work has gone into this in building the eureka tool to give my cutter back relief. A description is on my website:

    ok, so far, cutting a wheel to ensure the 0.6 mod cutter profile is good.




    The last picture is misleading as with the burs removed the wheel, in my opinion, looks good.


    Then a test to cut my first ever pinion. Even without it being supported by a tail stock, I'm pleased with the results.



    more to come!!

  2. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
    Cape Town, South Africa
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    Chris the relief on that cutter is excellent - after you re-made the tool. You have used a rounded gullet on the teeth. It looks (and is) great for the pinion. For wheels your clock will look strange if the wheels don't have square gullets. The cutter in your blog is a bit out of focus but it appears it would cut a square gullet. Where the wheels just quick tests to check all is well?
  3. Raynerd

    Raynerd Registered User

    Apr 11, 2004
    Teacher of Chemistry
    Manchester - UK
    Country Flag:
    Hi Tok, sad you feel like that but nope, the wheels will still have rounded bottoms. It is due to the way the cutters are formed. I'm sure to you true clock guys they may look odd, but they look nice to me!

    A little bit more done. For each clock I need 3x 96 tooth 0.6mod wheels and actually a 4th 96 tooth wheel with slightly smaller OD. I`m not clear on how the smaller OD works, I see why it is done but module is related to OD so I don`t understand how you can just go and change it because you need to! Anyway, that is what the plans call for and plenty of people have built this clock so it must work OK.

    Anyway, 6x 96tooth wheels:


    Praying that my dividing head was turning correctly and they would meet OK!

    A little polishing to do but here they are straight off the arbour.

    Then after a light polish. No point fully polishing until they have been crossed out
    jhe.1973 likes this.
  4. David S

    David S Registered User
    NAWCC Member

    Dec 18, 2011
    Professional Engineer - Retired
    Brockville, On Canada
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    Hi all, I have always wondered why the square gullet. From a strength perspective I would have thought that rounded would be prefered from an engineering point of view....not necessarily appearance. It would eliminate a stress riser at the root. Anyone know why they are rounded?
  5. Allan Wolff

    Allan Wolff Moderator
    NAWCC Member

    Mar 17, 2005
    Tulsa, OK
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    If you make a smaller wheel using the same module cutter, the teeth will be thinner. I suppose that would be OK as long as the teeth are not so thin that they become too weak to carry the load applied. Are they teeth on the smaller wheel cut to the same depth as the larger wheels?
  6. jhe.1973

    jhe.1973 Registered User
    NAWCC Business

    Feb 12, 2011
    Arizona, USA
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    Hello David,

    I had the same thoughts as you and as I looked into it further I found "Gears for Small Mechanisms" by W.O. Davis, M.B. E. which is a pretty exhaustive study of gearing.

    This book has tables for Swiss standards for designing teeth with round bottoms for the very reasons as you suspect.

    Personally, flat bottom teeth look to me to be a failure waiting to happen, so even in repairs, I will at least put a radius in the corners at the root.

    Hello Chris,

    Thanks so much for sharing your fine craftsmanship. Your work is very inspiring! Please keep it coming. :thumb:

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