missing English striking rack tail

[Willie X]

Does anyone have a formula, or a simple rule of thumb, on how long to make the tail piece for a typical English tall clock. I took in a clock today, the strike rack looks good but the tail piece is completely missing.

They aren't that hard to make but I have never had to make up one without the old broken one to go by.

Thanks to all, Willie X

 

[Mike Phelan]

Two approaches, Willie:
The distance from the pin on the rack tail to the rack pivot should be the same as the distance from the centre arbor pivot to the rack pivot.

That will work 99% of the time.

If you want to be really precise, you could measure the distance from steps 1-12 on the snail - let's call it "S", and the distance of 12 teeth on the rack, "T", and the distance from the teeth to the the rack pivot, "R".

Then, the length of the rack tail is R / (T / S).

Make sure the pin on the rack pin slopes towards the chamfered big step on the snail, and it's springy enough - a bit of old mainspring should be OK or thin hammered brass, depending on what was used originally.

HTH

 

[Willie X]

Mike,

Thank you very much. I will campare the results from both methods and give it a shot.

Willie X