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Close Slot in Pendulum Leader for Crutch Pin?

DannyBoy2k

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On my parents' grandfather clock, which is circa 1900 and well used, the slot in the pendulum leader has widened to the point that the slot is no longer a close fit to the crutch pin and an audible rattle can be heard going from tick to tock.

Click for larger
IMG_0307.JPG

Is there a standard procedure/best way to close this slot thereby increasing efficiency and getting rid of the rattle? Ideas I've contemplated:
  • Cutting a slot in some sheet brass and somehow gluing/soldering it in place to the leader.
  • Growing the diameter of the crutch pin with some slick tape, perhaps teflon plumbing tape.
  • Somehow working on the original piece with a punch or the like to close the slot.

The clock runs fine as is, but it would be nice to correct this part if the repair isn't too difficult.

Thanks!

~Dan
 

harold bain

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Dan, your suspension spring is too long, allowing the leader to sit too low which puts the pin too high. A slightly smaller suspension spring will fix it.
But you will then need to regulate the movement for timekeeping.
 

R. Croswell

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Applying some grease to the pin will often quiet the noise. Other than that, I would consider replacing the pin or sleeving it. Tape would not be a proper lasting repair, but it's your clock and may work for awhile is what I think.


Harold may be right, the pin is rather high up in the slot. Even if the pin is in the slot, changing the suspension spring could position the pin in an unworn area. It should still be lubricated.
 
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DannyBoy2k

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Thank you for the quick responses! My current suspension spring has a pin-to-hole distance of 19 mm and a thickness of 0.07 mm. Timesavers only has suspension springs longer than that (20.0 mm and up) with 0.07 mm thicknesses. If I reduce the thickness to 0.06 mm, they have several more options including one at 16 mm.

Do you believe a reduction from 0.07 mm to 0.06 mm in thickness would be an issue?

Thanks!

~Dan
 

Willie X

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Feb 9, 2008
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Anything over .005" should be fine.
A little slap/knock is fine also. It's really not a big issue on a robust movement like this.
Willie X
 

harold bain

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No, such a small change in thickness won't be a problem. Part # 24690 should shorten the suspension enough to work. You likely will have to hook the leader onto the suspension before putting it in place as it might be difficult to raise the leader high enough to hook it on.
 

Randy Beckett

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If you have enough adjustment room on the pendulum bob rate adjuster, you might also be able to use a suspension spring that is longer, allowing the beat adjuster to be turned 180 degrees, so that the pin is down, instead of up. This would put the pin in the lower portion of the groove, rather than the upper.

That is the way mine works, turn the pin up to insert through the hole at the top of the slot, then turn the adjuster to the bottom for normal use and adjustment.
 
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DannyBoy2k

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Thanks again for all the replies. Willie X made a comment that gave me pause.

Anything over .005" should be fine.
The current suspension spring at .07 mm is only 0.0028 inches thick. Is this suspension spring undersized? What is typical, if there is such a thing, for a grandfather clock movement? The thickest I see at timesavers is 0.08 mm. Willie X, did you perhaps mean .05 mm, not .005 inches?

Randy, I like your idea too, but I'm already towards the top range of the pendulum bob adjustment and don't think I have enough adjustability if the pendulum is lowered enough to allow the beat adjuster to rotate to the bottom.

As long as the thickness isn't an issue, I'm going to pull the trigger on Harold's suggestion.

Thanks,
Dan
 

DannyBoy2k

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As I want to return this clock before Christmas, I went ahead and ordered the part Harold suggested as well as a Hermle suspension spring that is even slightly shorter at 14.5 mm pin-to-hole. I tested the crutch pin in the slot and it's much better lower down and doesn't bind even all the way at the bottom. Seeing as how the 0.0025" Hermle suspension is designed for their triple chime grandfather movement, 0.06 mm (0.0023") thickness seems fine.

So, while I'm waiting for that to arrive... assuming the crutch pin had been in the correct position and I had this issue, what would be the best way to correct a sloppy fit? R. Croswell had mentioned replacing or sleeving the crutch pin. Are there any operations that can be done on the slot, or does that pretty much involve fabricating the whole pendulum leader?

Thanks.
Dan
 

harold bain

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Dan, these parts don't normally wear to the point of needing such attention. I suspect at some time your suspension spring was replaced with whatever was handy for the repairman. It worked well enough. Make sure your replacement isn't too long, as that pin shouldn't bottom out in the slot.
 

DannyBoy2k

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Harold, roger that. You said "too long", but I'm assuming you meant too short as the shorter the spring, the closer the pin will be to the bottom of the slot. Many thanks for the help, especially for researching that part for me.

~Dan
 

harold bain

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Harold, roger that. You said "too long", but I'm assuming you meant too short as the shorter the spring, the closer the pin will be to the bottom of the slot. Many thanks for the help, especially for researching that part for me.

~Dan
Right, Dan. Getting too close to bedtime, I guess:whistle:
 

Willie X

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Dan,
Yes, "anything over .005" was not a good statement. The correct thickness for the spring you need would be around .0025" to .003". Only the older ribbon style springs, for big clocks with heavy pendulums, will fall into the .005 to .007" category.
 

DannyBoy2k

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Just to close out this thread, the part 24690 from Timesavers did the trick for me. I did have to put a .001" brass shim one one side to keep it from wobbling in the slot it is mounted in. I'm assuming/hoping that's not an atypical thing to have to do. A little grease (B52) on the crutch pin also helped quiet down the rattling sound. All I'm hearing now is the pleasant tick/tock of a properly running movement.

Thanks!

~Dan
 

Kent Dold

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Jan 7, 2021
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Glad you got it figured out. I have had success just slipping some felt around the crutch. Make sure your pin is square in the slot. A slight offset can cause the pendulum to slightly wobble causing the rattle sound.
 

bruce linde

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i would not use felt, as it will compress over time... and probably isn't thin enough for more precise tweaking.

i don't remember from where, but i purchased a set of assorted brass shim stock. the thinnest one is like brass paper and can be torn by hand. i will sometimes wrap a bit of that around a banjo or tall case clock crutch fork, or a regulator crutch pin, to take up just a bit of excess slop and leave the desired just enough amount.
 

Kent Dold

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Jan 7, 2021
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i would not use felt, as it will compress over time... and probably isn't thin enough for more precise tweaking.

i don't remember from where, but i purchased a set of assorted brass shim stock. the thinnest one is like brass paper and can be torn by hand. i will sometimes wrap a bit of that around a banjo or tall case clock crutch fork, or a regulator crutch pin, to take up just a bit of excess slop and leave the desired just enough amount.
The felt material was meant as a temporary solution. I should have been more specific. Inlay and reslotting the wood or making a brass layover is best.
 
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