Moon drive gear for Hermle movement

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  • #49253
    cazclocker
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    Can anyone tell me how to find a moon drive gear for a UW#32342 Hermle movement? I’m replacing the old Urgos movement in my dad’s mid-late-’60’s to early-’70’s grandfather clock. My mom & dad didn’t know they should be servicing it every few years, so it never got serviced for 35 years! I replaced the Urgos 32/3 with a Hermle UW#32342 and it keeps great time, but I just realized it didn’t ship with the little gear on the hourpipe that drives the 3-wheel moon drive train. I tried pulling the moon drive wheel off the old Urgos but it won’t fit on the Hermle hourpipe! I mic’d both hourpipes, and the Hermle hourpipe is .007″ bigger than the Urgos one. Not much, but enough to stop the wheel from mounting. I am somewhat certain that I could probably bore the existing mounting hole in the old drive gear by just a few thousandths on my lathe, but I wonder if I would be better off if I could find a new one.

    What would you guys do?
    …Doug

    #59702
    bernie weishapl
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    Doug the UW series is Urgos. Hermle bought them out but they are still Urgos movements. The one thing I can say is the new Urgos movements use hermle hands. You might check with Mark Butterworth at Butterworth clocks or Black Forest Imports for your gear. If you have the old gear you might bore it out and see if it will work. I probably would do that myself and if it didn’t work buy one. Black Forest Imports has them for the UW 32/66 and Urgos 03.

    http://www.blackforestimports.com/advancedwebpage.aspx?cg=570&cd=5&SBCatPage=&TiledLayout=True

    #59703
    cazclocker
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    Thanks Bernie, I appreciate the input. I bought the new movement from Butterworth Clocks, great guy. I contacted Mark and he says he doesn’t have the moon drive gears. Thanks for pointing me to Black Forest Imports, though. This morning I’m going to try boring out the old gear. If that doesn’t work, it looks like Black Forest Imports is my next step.
    PS…I’ll report the results.
    …Doug

    #59704
    cazclocker
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    Hi, I ended up enlarging the center bore in the old moon drive wheel on my lathe. What really drove me nuts was that I knew I had a home made boring bar that I made a long time ago, but when I went to use it I couldn’t find it! So I had to make a whole new one on the spot. It was pretty crude, but it worked reasonably well. Anyway, I bored out a thousandth or so, removed it from my wheel chuck to see if it would fit yet – back and forth about 4 times until it finally fit well. Glad to report it works well, I have it adjusted so the moon dial advances at within 5 minutes or so of midnight. Woo-hoo!
    Note to self – I need more practice hanging the pendulum from the front door with the back screwed shut – can’t see what I’m doing, so I have to “go by feel”. It’s not easy! Maybe with more practice…
    …Doug
    PS…..Hey Bernie, thank you for telling me the Hermle UW series are still Urgos movements. I had no idea that Hermle bought Urgos out. When did that happen?

    #59705
    bernie weishapl
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    Doug it happened a few years ago when Urgos went bankrupt. Glad to see it worked for you. As for doing pendulums in the dark. Get used to it because it happens all the time.

    #59706
    tukat44
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    • Topics Started: 8
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    Have been looking at clocks and watches for some time now and I might have tried to use a cutting broach to enlarge the hole on that moon gear- is the lathe the best way (I have zero experience)?

    #59707
    bernie weishapl
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    If you had a broach that big yes you could use it and sneak up on the proper sized hole.

    #59708
    cazclocker
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    @Bernie Weishapl wrote:

    If you had a broach that big yes you could use it and sneak up on the proper sized hole.

    In retrospect, I suppose I could have used a cutting broach. None of mine could have done the job, all mine are too small for the center bore for the gear bore I was trying to enlarge so I would have had to order a larger broach and wait for it to get here. One reason I thought that using my lathe would be better than broaching is that the hour pipe is straight, and with a boring tool in my cross slide I can also bore the inside diameter of the moon drive gear straight – so the surface profiles will always match as long as I have my cross slide set at 90 degrees. If I had used a broach, the inside diameter of the gear would have become somewhat tapered because the broach is tapered. But I guess a partial answer would have been to broach the gear from one side just a little bit, and then broach from the other side, similar to how we do clock plates. But that would have left both ends of the gear’s bore wide while the center was narrow – it’s still not straight! So overall, I still consider the lathe to be the superior method because it yields the most desirable result even though it’s more trouble.
    That being said, I think I’m going to order some larger cutting broaches just to have them on hand for things like this!
    …Doug

    #59709
    bernie weishapl
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    • Topics Started: 58
    • Total Posts: 1218

    I agree Doug that a broach would make it easy to do fine adjustments but the lathe IMHO would be much more accurate.

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cazclockerMoon drive gear for Hermle movement