Drilling and sanding

The next logical step in the clock is to drill holes for all the arbors and the like.  For large-ish wheels, they can be comfortably held in the lathe chuck, like so.

For the pinions, I was concerned both with getting a hole that was truly axial and with not damaging the pinion leaves.  I remembered (somewhere) reading about cutting a recess in a wax chuck to receive the outer diameter of a wheel.  Once cut, the wheel would be set into this recess and the center could be drilled correctly with certainty.  This seemed like a good idea, so I chucked a piece of scrap pine in the lathe chuck and bored a recess to receive each pinion.  I made sure that the recess wasn't too deep, so that I would be able to grip the pinion with my fingers to remove it.  I cut aggressively with the boring tool first, and then when I got close, cut in 0.0025" increments until a snug fit.  Here is one pinion fit into the recess.

Here is another view as drilling is in progress.  I gave myself practice striking centers with the graver, which was much more efficient than using a center drill.

I used three drills, starting from 1/16" to 1/8" to ensure that I didn't have much tearout from any pinion or wheel.

The resulting pinion holes were indeed dead on center.  Since the arbors are 1/8" exactly, I broached the holes slightly larger to give a smooth, low-friction fit.

Emboldened by my success, I used a wobble stick and lathe faceplate to drill the precise holes on the escapement detent and hour rack.  This turned out to be less harrowing than drilling by hand, and ensured that no parts got damaged!

After this, I sanded off the paper, using grits up to 320 and removed the dust with a rag dampened with mineral spirits.  I think I really only needed to go to 220, though.

Trying all the parts on the depthing tool indicated that the gears run very smoothly.  All the time I spent sanding paid off!  But the hour rack had a design flaw.  The teeth of the ratchet pinion (right) foul on the rack teeth (left).

So to fix this, I cut and sanded the hour rack teeth to allow the pinion to run smoothly, which wasn't too hard.