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My Numechron Digital Clock design was inspired by the Pennwood Model 1364 digital clock. Clocks of this type originated in the 1930s, and were built for many years by the Pennwood and Lawson companies in many different wood, metal, and plastic case styles.
I really liked the Art Deco style of the Model 1364 case and chose to emulate it, although my clock is considerably larger than the prototype. While mimicking the original style, I employed considerable open space in the case design so that the clock’s internals would be visible.
A Pennwood employee, F. Greenwalt, patented the mechanism for this type of clock in 1935. He developed an ingenious set of wheels, cams, and levers to flip the numerals and operate the clock. I consulted the original patent to design the mechanism for my clock.
All of the wooden parts were designed using Carvewright Designer software and machined with the Carvewright machine.
The hours and minutes numerals are made of 1/4” poplar sourced from Home Depot. The numeral segments were a two-sided carve, the mitered top and bottom edges of the numeral rectangles carved to the proper angles on the back side. (These could have been cut with my table saw, but the Carvewright makes an easier job of machining these relatively small parts that would be a challenge to hold safely while sawing.) Centerline text was used on the front. The seconds wheel segments were made of 1/2” poplar, also sourced from Home Depot. Again, the mitered edges were carved from the back. The Designer 3D tools were very useful to create the miters and the curved face of the seconds segments. Centerline Text and Conforming Vectors were used for the seconds numerals.
Red oak was used for the supports, motor mount, and other parts. Red oak was also used for the bottom of the case. Select pine was used for the clock’s base, and the ribs that make up the case sides and top. The front was made of 1/4” Baltic birch plywood. While it could have been cut in one piece, Model 1364 had an interesting arrangement of veneer, so I made the front of multiple pieces to emulate the original. The pieces were laid out in Designer and cut by the Carvewright with rabbets to make nice lap joints for easy and solid assembly.
In addition to the wooden parts, some brass tubing, springs, and a few ball bearings were used for the mechanism. A 1 RPM synchronous motor powers the clock and keeps accurate time. Motors of this type are used in time card machines and may be readily sourced as replacement parts for about $30.
I have seen photos of many different wood clocks, but I think it is safe to say that Numechron is unique.
Here are links to a couple of short videos:
Video - Numechron
Video - Designing and Making Numechron
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Originally Posted by Cody Pierce
