Reply To: Cylinder Escapement

[Bob Tascione]

Hi Chris,
I probably should have gone into a bit more detail about how the pinion is attached to the escape wheel but had to run somewhere for a few minutes when I last posted. It actually should be lightly riveted to the wheel. The escape wheel is hardened so I find that just tapping the pinion arbor out causes the rivet to fold upward leaving it intact to be used again. These generally come out (at least for me) much easier than a balance staff without the rivet doing any damage to the hole. If the rivet breaks off or is removed then a light undercut can be made to the pinion shoulder for re-riveting. This is one reason that the hub height of the wheel will usually need to be reduced. Grinding can be done without having to temper the hub but if the hole needs to be reamed out to fit the arbor shoulder then you’ll need to temper the hole and shoulder anyway. You can then turn down the hub if needed. I do the tempering process with flame and a needle which is inserted into the hole. The needle is then heated until the hub and a tiny bit of the surrounding area just turns a dark blue color and is then withdrawn from the heat. It’s very important that the tempering doesn’t pass through the arms to the rim and into impulse faces. The hole can then be reamed to size. I use a staking set and punches to replace the arbor.
If you have a depthing tool then this might give you a better perspective for checking to see if the wheel is suitable for the cylinder you’ll be using. I would think though that all real testing such as passage/fouling, drops, inside and outside shakes etc. would need to be checked while in the movement.

Hope this helps Chris,
Bob