Monday, November 14, 2016

This is a gonna be a tough one.

The broken gathering pallet shaft.
I knew it going in because I've had them before,  Only 3 in over 25 years, but they were all brutal.  I'm sure other clocksmiths have their own "worst" jobs ever, but these are definitely one of mine.  If this wasn't a regular longtime customer, that has never complained about costs, I would have passed on this job in a heartbeat.
And just to put a little icing on this crap cake, the end of the shaft and the gathering pallet were missing completely.  We'll get into the gathering pallet later.
Somewhat of a rare clock movement, with a lot of quality in it, purchased at auction.  Looked like a simple clean and oil, couple of bushings, and out the door it goes. Then you pull the dial and see the gathering pallet.  Well actually you don't see it cause it's not there, but you see the problem.  It's also obvious that someone had tried a really desperate repair that turned out horribly, doing a lot more damage along the way.  Whoever put this into the auction knew it, but this isn't something you will say upfront, because then nobody would opt to buy it.

I don't even know the odds of it, but at the time the bad one came in, I just happened to have a identical twin, but the same maker, on my test stand. The repair was doable without it but at least I could see the shape and size of the original gathering pallet. Even more than that though was it made explaining to the client the severity of the problem with only a couple pics.

Missing shaft and pallet
This is what should be there
 The gathering pallet is probably the one part of any old clock that needs to be made by hand.  This is the piece that makes the clock count the number of times it strikes, and then it's the brake that stops everything.  They are cut and filed out of a solid block of steel, and are the oddest shape that one could even imagine. There are curves, flat spots circles and a square going thru the center to fit the pallet shaft. the tolerances and clearances also need to be very close.

Donor steel and finished pawl
The existing arbor now needed to be extended which is tough.  I elected to use a drill for the shaft because the size quality and hardness of the steel.  A butt joint would not have the necessary strength so I turned the end of the drill down and backdrilled the existing shaft for a press fit.  The joint was then brazed because solder would not be strong enough and then the excess braze turned down in the lathe to end up with a smoothe shaft.
Pieces before joining
Below is a pic of the repaired shaft set up in the jewelers lathe with a filing attachment so that the end can be filed to a perfect square. Prior to this step, and the backdrilling of the shaft, I needed to make a brass adaptor to hold the gear.  Since there was no option but to hold it by the pinion (small gear on end), these teeth needed to be protected.  Here is a pic of the piece.
Brass collet in steel collet

Setup for filing
 These 2 pics are the completed shaft and also the completed shaft in the clock.

Here is a short video clip of the finished part and how it functions.

video

I was happy to see this job completed and out of here.