Pendulum repair

tracerjack

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This little pendulum (1 1/4 diameter) has had the tip broken off so that the bob can’t be lowered enough to regulate the clock. Of course it has some odd thread size, but since I have to make a new insert, I can adapt the thread size for the hook and rating nut by threading it to something standard. My question is if anyone knows how the threads on these flat pieces were/are cut?
FA8D0156-B07C-436C-A335-5B425B8AF92B.jpeg B7B4B34D-7A26-4808-A272-08E1F63A890C.jpeg
 
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Ralph

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Using a steel nut, if you taper the tip of the part to thread, so you can start the nut, you might be able to form the threads.

Ralph
 

Willie X

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I would use the original piece. Cut it off about 1/8" above the bottom of the bob.
Then split a length of threaded brass rod for about 3/8", file for a snug fit and solder it over the original piece.

Alternately, for a smaller diameter rating rod, you could do the same cut off but notch the original piece (about 3/8") for a snug fit of a thinner brass threaded rod. You can file flats on the sides of the new rating rod for better contact and a stronger solder joint.

Willie X
 
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bruce linde

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what about lathing a brass rod into the right diameter, threading it, milling (or grinding, for guys like me who don't have milling machines), and then splicing it into the original piece by filing a notch to fit and then silver soldering?

ertwert.jpg
 

tracerjack

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These are all good suggestions for fixing the one I have, but I failed to mention the openings in the bob won’t take a rod. It’s a snug fit for a flat strap. Since the threads in the original are quite shallow, using a steel nut as a die just might work. If not, I’ll drill out the lead to take a rod.
 
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shutterbug

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You can get thread checking tools inexpensively. I'd match the thread and use a regular die for the threads.
 

Ralph

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A regular die can’t work. It’s dependent on a cylindrical body, or enough body to bridge the gaps in the die.

To the original question, I would suspect they were formed (deformed).

Ralph
 

Dick C

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A regular die can’t work. It’s dependent on a cylindrical body, or enough body to bridge the gaps in the die.

To the original question, I would suspect they were formed (deformed).

Ralph
How about adding enough flat brass of different sizes to the tips of the new flat brass piece using super glue. Then cutting the threads
and removing the glue/brass. Would this work?
 

Ralph

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I was thinking along those lines, maybe even solder some material to the flats and after threading , remove added pieces and clean up. There are a number of suitable ways to fix or make a new pendulum rod, but that wasn’t his question. ?.?

Ralph
 

Willie X

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A flat rating rod is to be avoided when possible. It's only plus was cost cutting.
Willie X
 

tracerjack

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I did check the original threads. Measured 2.7 mm. The pitch was .45 if I remember correctly or something near that. I already shaped a new flat, so I’m going to mess around with it and see what happens. I’m still curious how cutting a flat is done. Possibly they had dies without cutouts that would thread a flat. Willie X’s post that flats were a cost cutting measure and inferior to rod has me convinced to play around with the flat, but in the end upgrade this little pendulum to rod.
 

tracerjack

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Can the leader be lengthened a bit? It might be an easier fix.
I did check on that, but the suspension spring and leader are a unit. Mine was already longer than any offered by Timesavers. I’m confident I can fix the pendulum, it’s just a matter of deciding which method to use.
 

dickstorer

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Bruce, you said "grinding for guys like me, etc." Please do not grind brass, use a belt sander instead. Never grind any thing that does not make sparks. You actually risk serious injury when the grinding wheel fills up with brass or any thing else that does not make sparks. If the grinding wheel gets to hot from not being able to breathe
 

shutterbug

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I think you will be able to thread it with a die, but you'll need to control the parts. A lathe would hold everything nice and straight, and you could figure out a way to turn it without using the motor.
 

tracerjack

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With only access to hand tools, I was finally able to fix this tiny pendulum. The steel nut as a die didn't work on the flat replacement strip I'd made, although that could have been more from my lacking skill. I didn't have a file fine enough for hand filing threads, although I tried anyway. With that out, I then had to abandon using rod for the finished size, because my first attempt at drilling out the bob immediately caused the lead type backing to start crumbling. And the lead back was thin, so I could easily envision it breaking out completely. HAC bobs for their Delft clocks have a distinctive groove on the front and finding a HAC replacement would be difficult. I've only seen one come up, and I was way outbid. So, with caution in mind, I moved on to a third attempt. I threaded a 3/32 brass rod to the proper length on each end, preened the center portion to the needed 1/8 inch and then filed the whole length to the proper thickness. With close inspection, the center portion isn't pretty, but "Whose lookin'?" I'm just happy I can now properly rate the clock.
IMG_0234.JPEG
 
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shutterbug

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An interesting and practical solution to the problem. It makes me wonder if a rod could be split down the center, clamped on each side of the original part and threaded that way? I'll have to give it a try if I'm ever faced with that issue.
 

Wayne A

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Looks good to me and its swinging. Given the small size was thinking you didnt have much choice but the start round and file flat.
 

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