Regulating

Now that I've been running the clock for some time, it looks like it was running consistently fast.  Disassembling the clock and examining, I found that

• The pendulum rod weighed 200g
• The pendulum rod (from arbor center to end) was 43"
• The pendulum bob weighed 100g

Putting this together, the farthest the center of mass could be from the arbor is about 29".  That's far shorter than the nearly 39" it should be.   Tweaking these values a bit, it looked like I needed to reduce the weight of the rod to around 50g and increase the bob weight to over 300g in order to be able to make a band of adjustments around the correct length.

Given that direction, I used a router to grind down the pendulum rod to quite bit thinner.  This took off about 100g, but also made somewhat of a mess.  Fortunately, I could make this the back so it's not so obvious.  I then tapered the rest of the rod using a plane.  In the end, the pendulum rod weighed 60g and is quite delicate.

I also cut two more circles of plywood to add additional weight to the back of the pendulum bob -- now it is 325g.

Given those two changes, I found that the clock had difficulty running.  Earlier calculations suggested that this would happen, because more lifting force needs to be applied at the anchor.  Therefore, I very carefully filed back the anchor teeth on the escapement to reduce the lift.  I may have overdone the exit tooth, but after applying more Slip-It to the gear teeth and pivots, the clock runs. 

After these changes, with the pendulum bob roughly in the middle of its range, the clock actually runs slow by about a minute every hour.  That's a success: I can now adjust both faster and slower as needed.  So now it remains to slowly bring it into regulation over the next few days.

Pins and slip-it

Now that the clock "runs," I've been tuning it so that it runs well.  The largest apparent problem was that that the anchor slipped on its arbor.  This meant that sometimes the clock would run with an even beat, and then lose this...  So to fix the problem, I made a small pin, like the one shown below:

In the end, the pin shown here didn't grip well, so I turned a second one that was tapered.  Then, with the anchor in place, I drilled through the anchor into its arbor and gently hammered the pin in place.

This helped with keeping the beat even, but the clock still was stopping abruptly.  After talking with my father, we settled on lubricating the teeth.  Nearly all wooden clock enthusiasts argue strongly against such a move, most wood lubricants or finishes turn hopelessly gummy and become hard to remove.  However, one caught our attention: slipit.  They sell two kinds, a wood-working kind (without silicone) and a "mechanics" kind (with silicone).  The reviews indicate that the kind without silicone doesn't work well, but the kind WITH silicone seems to work better.

So we settled on the stuff with silicone, and I applied it to all gear teeth with a small paintbrush.  After putting on a frightfully large weight (9 lb 8 oz), the clock has worked absolutely smoothly since!  Amazing!

Now, I did notice something odd.  Although the minute hand seems to run at about half speed, the hour hand runs at the right speed.  Weird.  I guess I made TWO gear ratio calculation errors...