I've made a jeweled bearing for the lower pivot of the escape wheel arbor. The bearing is similar to the balance arbor bearings, except it has a pivot bearing which supports the lower pivot of the escape wheel arbor. It's made from a 2-56 stainless steel socket-head set srew.

The bearing's jewel bore is made off-center, and the bearing is made to rotate a little. This permits adjustment of the clearance between the escape wheel and the roller table on the balance arbor when the clock is being set up to run. Since the jewel bearing will be rotated, it has no mounting holes -- it will be held by a set screw seated in the balance plate.

The bearing is made from 5/16" hexagonal brass rod. The hex shape permits adjusting the bearing with a little 5/16" box-end wrench at set-up time.

The steps for making it are similar to those for making the balance bearings: First, a spigot is turned on the hex rod which will fit in a hole on the horizontal balance plate. Then the bearing is parted from the hex rod, and inserted into a 4-jaw chuck, which clamps the bearing by the spigot.

The four-jaw chuck has jaws which adjust independently. This permits off-setting the bearing, so that the bore for the jewel can be made off-center -- the offset is about 1/16". First a hole is drilled for threads for a 2-56 screw, then the hole is tapped in the lathe.

Then I cut the jewel bore with the miniature boring tool, as described previously. The jewel is held in its setting by watchmakers shellac. The jewel is the same as those used for the balance bearings.

The stainless steel screw will support the bottom pivot of the escape wheel arbor. The end of the set screw is hollow-pointed, which will make a good bearing. Since it's threaded, it can also be adjusted up or down, and it can also be removed to clean the bearing. It is held in place by a locknut.

There is already a hole in the upper balance plate for the eccentric bearing. I just had to size the hole to fit the spigot on the eccentric bearing, and make a hole in the edge of the plate for the 0-80 set screw which holds it in place.

Todays' links:

Drilling eccentric
Tapping eccentric
Minibore
Boring eccentric
Eccentric 1
Eccentric 2
Eccentric 3
Upper plate 1
Upper plate 2
Eccentric drawing, GIF