Reinserting gong coil to block

Discussion in 'Clock Repair' started by SuffolkM, Oct 17, 2020.

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  1. SuffolkM

    SuffolkM Registered User
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    Jun 15, 2020
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    Hi folks,

    Photos attached.

    This is one of a pair of coils from a W&H ting-tang which I recently acquired and have restored. This one is a ting-thud. The coil itself is fine, but with just the force of my hand I found I could remove it from the block, hence the lack of proper transfer of the vibrations and the severe damping of the note, I think.

    As I understand it, soldering is not the answer. It seems so nicely finished, I can't really tell what the original construction technique might have been. I have been considering grinding the tapered end to a similar, but larger shape just a few mil into the rod to take up the play, but I can't think of a good way to insert it with the required force afterwards.

    I'd appreciate some suggestions on what to do!

    Best wishes
    Michael

    IMG_7060.jpeg IMG_7059.jpeg IMG_7058.jpeg IMG_7057.jpeg IMG_7055.jpeg
     
  2. chimeclockfan

    chimeclockfan Registered User
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    Dec 21, 2006
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    The coil gongs were normally brazed into their fitting blocks so it's unusual to see the coil come out like this.
     
  3. bruce linde

    bruce linde Technical Admin
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    Nov 13, 2011
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    i would be concerned about the high temperatures involved in brazing (> 450 degrees) and think that soldering would be fine.

    if you press the gong into the slot by hand... is there a point where it feels like it starts to get snug(ger)? i wonder if you could peen the hole slightly to make it a snugger fit, tap it into place, and then lock it down with a touch of solder? (why do you say 'soldering is not the answer'?)
     
  4. wow

    wow Registered User
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    Jun 24, 2008
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    Bruce, I have found that solder does not work in gongs or rods because the solder is softer than the steel and causes resonance loss. You end up with a thud sound. If brazing is not possible, driving or pressing it in should work. I would mount the gong very tightly in a vice and drive the block on with a brass hammer. No matter what method you use, you will need to tune the gongs if you want the minor third interval normally found in bim bam clocks. The broken gong will be a higher pitch than it was originally.
     
  5. bangster

    bangster Moderator
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    I was going to say: clamp a vise grip onto the tang of the coil, then use a hammer on the vise grip to drive the tang into the block. But wow's suggestion may be easier.
     
  6. bruce linde

    bruce linde Technical Admin
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    agree... i was thinking 99% would be the press fit, and just a bit of solder to help make sure it didn't slip. i like the vise idea....
     
  7. shutterbug

    shutterbug Moderator
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    It doesn't really look broken to me. If there's a piece stuck in the slot though, you'll need to correct that or make a new slot. It's also possible to use a round hole, but then you'd be cutting more off the coil and messing up the tuning of it. You could also try cutting a round hole a little smaller than the width of the tang, and then when you drive it into the hole it will cut it's own slots on the sides of the brass fitting and be quite tight.
     
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  8. SuffolkM

    SuffolkM Registered User
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    Jun 15, 2020
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    Thanks for the help. I'll let you know how it goes! I figure maybe sharpening the point might help when driving it into the slot. I figure I don't get many goes at this before it's properly loose. Wish me luck...

    Michael
     
  9. SuffolkM

    SuffolkM Registered User
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    No luck on this I'm afraid. I tried to drive the gong into the block in various ways, but could not get it to take. I then tried sharpening the end to a blade, but although it fitted more tightly, it was still a dull sound. After this I tried heating the block and after tinning the (now sharp) end of the gong I silver soldered it in, which gave a very strong and sturdy fit. The tone was improved, now sounding more like a 'dong' with limited resonance, but still not a real 'tang'. I think I have reached the end of the road with this one, which is a pity. It does go to show how critical these fittings are.
     
  10. wow

    wow Registered User
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    If you will post a photo of the whole thing as well as the good one (With measurements), I will be glad to look through my bone pile. I have a couple of large boxes of old gongs and blocks.
    Will
     
  11. JimmyOz

    JimmyOz Registered User

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    I had this happen a few years ago, also tried to silver solder it, it was not great. I then had a think and to get the coil to sound better I cut a small steel wedge with not a lot of angle, filed one of the flats of the going coil again with not a lot of angle. With the solder still in the housing I heated it and at the melting point drove the wedge in, just be careful it does not splash back as you drive the wedge in. It sounded a lot better as I think the wedge gave it tension, cut the end of the wedge off and you can't ever see it. Worth a try?
     
  12. SuffolkM

    SuffolkM Registered User
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    Hello all,

    A big thank you for all the help, and particularly to Will (Wow) for the extremely kind gesture of offering a spare part from the bone pile. That is really very good of you, thanks!

    I have resolved this with a replacement gong I had to hand, which had a block that was almost right for the hole spacing (easy to retap) and a pitch lower than the one I needed but the right diameter (lucky). I used a Dremel circular cutting disk to reduce the length of the gong, taking ever-smaller cuts until I achieved a perfect interval between the two notes. The total removed was less than you might expect, less than 20mm, and now the gongs have a perfect note with a lovely, full and harmonious pairing again. This clock sounds fantastic once again.

    I am quite relieved. Getting the original gong to resonate was far more challenging than I expected.

    Best wishes
    Michael
     
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  13. wow

    wow Registered User
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    Michael, so good to heat you got it. Quite a relief when all is resolved.
     

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