Removing Cannon Pinions Hints
This page does not relate to French clocks and others that have the hand friction dictated by a removable cannon pinion.
Very occasionally you need to remove the friction fit cannon pinion from the centre arbor to rebush or remove a barrel This does not happen often because there is not a lot of force on this end of the centre arbor.
When you need to remove the cannon pinion, you will find it is usually very tight! The following methods have been suggested by other clockmakers as to how they remove the cannon pinion.
The following suggestions were from Jeff Major, Mark D. Meadows, Dick Muller, Bernie Weishapl
There are two methods that seem to have universal use.
Using a drill press
Construct a support block for the front plate by either:-
- Using a short piece or two of pipe (6" or so long) which the large gear inside the plates just fits into
- Make a wooden block that has a slot wide enough for the shaft for the first 1/2 " or so and drilled out for the wheel this puts support very close to the hole in the front plate and it eliminates any springing of the metal which just makes it harder to press off.
Stand the support on the drill press table with the movement plate on top of it, the big gear inside the pipe (if you have not been able to remove it).
Clamp the drill press chuck tightly onto the clock's centre shaft about halfway down, and use the handles to press downward slowly. It works like a charm. Sometimes you have to take a second grip higher up to complete the removal.
Using a modified C Clamp
Using a deep throated C-clamp, the bottom solid jaw has a slot cut in it to make sure the brass collet on a Hermle can pass through. The top part that screws down I took a drill bit and coned it out. I then put the slotted piece inside the plate and on the top I put a old hand nut on the cannon pinion with the top part of the C clamp on it. If you screw slowly and carefully it will push it right on out. Have never bent one yet.
Reassembly
You can either,
- Gently drive the pinion back on with a hollow punch after the clock is assembled, with the movement resting on a hardwood block to support the rear end of the shaft.
- Press it back on with the drill press as well. Chuck a hollow punch in the chuck and simply press it on. (Back it up properly of course) You have great control and can press it on as far as you want to with out marring up anything.
