replacing damaged ratchet wheel teeth on a longcase clock great wheel

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MtKuile
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replacing damaged ratchet wheel teeth on a longcase clock great wheel

Post by MtKuile » Tue Feb 02, 2016 9:05 pm

I am working on a longcase clock from 1770 and noticed that two teeth on the ratchet wheel of the going train's great wheel were badly damaged. I decided to replace these damaged teeth, because the risk that one of these teeth would break under the force of the going train's weight worried me. If that were to happen a cascade of broken ratchet wheel teeth might ensue with the weight crashing to the floor.

On closer scrutiny it appeared that these two damaged teeth sat in a strip of eight consecutive teeth that were a replacement already and were neatly soldered in as a strip of eight teeth into the ratchet wheel. Almost invisibly so. This strip was not only soldered in place but also secured with two pins that went through the strip of eight teeth vertically into the barrel of the great wheel. When I tried to heat up the strip of eight teeth to take them out of the ratchet wheel I noticed that the solder did not want to melt if I used my micro gas torch. The solder only wanted to melt if I used my main blow torch. This made me wonder if the solder that had been used to fix the strip of eight teeth was perhaps hard solder?

So I asked my tutor at West Dean College whether I should use hard or soft solder once I would solder a new strip of eight teeth into place? His answer was: definitely use soft solder. If you use hard solder which needs a much hotter gas flame you risk ruining the barrel of the great wheel. I have now put the strip of eight teeth back into place using soft solder and put two pins through the strip as well to secure them into the barrel. I trust this work.

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