Sunday, November 16, 2014

Flying pendulum escapement

I came across the flying pendulum escapement, which is mesmerizing.  So I started with a simple wooden frame cut from scrap wood.
The main arbor is made from a brass rod, and is supported on two brass thrust bearings.  I cut these from 1/4" brass rod on the lathe.  I first beveled the end with a wide drill bit, and then center drilled to a depth of 1/8" with a 5/64" bit.

I pushed these into slightly undersized holes in the frame, so that they are flush with the surface.
Once these were installed, I cut a pivot into one end of the arbor.  The end of the pivot is 1/8" long and 1/16" diameter -- giving a little clearance in the bearing.  I did most of the work using the slide rest, and then finished it using a hand graver.  I checked the polish under 2.5x magnification to make sure it was reasonably smooth and the end rounded.

Once this was made, I cut to rod to length, and cut a matching pivot on the other side.  This fits into the frame and allows the arbor to turn freely.
Again using the lathe, I cut a take-up spool for the cord and center drilled it to fit the arbor.  A 1/4" drill bit seemed to work, giving a snug fit to the arbor.
The escapement has a rotating arm.  I cut this from 1/4" brass rod, and drilled two 1/8" holes at right angles to the axis.  I then turned the arbor to a diameter of 1/8" for an inch or so to receive the arm.  This wasn't a tight fit, so I soldered it in place.

After this was completed, I added the rods to catch the pendulum as it passes.  I didn't really have any systematic way to do this, and it ended up looking OK.
However, it didn't work well.  For one, it seems to work best when driven by a very light weight -- about 0.5 oz.  Additionally, the spool seemed too big.  I also moved the rods around, so that it looked a little different.
Even still, it's extremely temperamental and difficult to get to run smoothly...  But here's the best run.


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