It’s not my intention to repeat info about gears that you can find in textbooks, The Machinery’s Handbook or from searches on the web. In most other gear trains, pinions (the small gears) turn wheels (the large gears) in order to convert the fast, lowpower revolutions of a motor shaft to an output shaft that turns slower but has more torque. An interrupt is triggered every 0.1 seconds and adjusts an internal clock as needed. For those interested, I’ve included a mathematical discussion of gear ratios and pendulum lengths (at right).
I recently went to a woodworking trade show and asked 3 wood finishing suppliers about this, and I was appalled that they didn’t know whether their own products were dyes or stains. Only a few spots on the clock required lubrication, which consisted of drawing on the wood parts with a lead pencil. I have looked at the different books on wooden clock making, but haven’t decided to give it a try yet.
I then have a small vertical belt sander which I use to get the final accuracy on the gears. I’ve decided to take on the wooden clock in this Instructable, and hopefully share what I have learned to help others with similar interests. The quarter section gears used in the Inspiration clock were mass produced products and required equipment and skill to manufacture.
Not to mention the sale tables at these meetings can be a source for reasonably priced used tools. Be sure to also check out the second video, especially around 1:50 when I show what happens when an escapement gear goes much faster than a normal clock. I just looked at a web site that had wooden clock pictures and they were all the same wood. You can buy wooden clocks from kits, but I wanted mine to be completely handcrafted, with all parts hand cut.” Using computer design software and an engineering design application, he came up with a concept, but it took six months to get the bugs out.
But for a quick reference, here are the Gears and their teeth: Each line represents an axle Pinion 1 – 12 teeth Wheel 1 – 36 teeth , Pinion 2 – 10 teeth Wheel 2 – 40 teeth, Pinion 3 – 8 teeth Wheel 3 – 40 teeth, Pinion 4 – 12 teeth Wheel 4 – 40 teeth, Pinion 5 10 teeth Wheel 5 – 36 teeth. It will run as is with the dowels but once you add a gear train to it the dowels will cause too much friction. There is so much info on the web about building wooden clocks, one just need look.
This changes the speed by which the driving gear moves the next and is determined by the size and teeth number of the pinion. Since you are already familiar with Gary Gresham’s work, look at his links re: Brian Law’s clock plans, he uses MDF for gears. Clocks and parts THIS old have 0% or nearly 0. I work with wood on a daily basis. Following your clock plan’s instructions, assemble the wheels, pinions, and spacers using the arbors.
To turn the hour hand, we need a train of gears called the dial train, shown on p. 33. This is simply a four-gear 12-to-l reduction system that takes its power from the center arbor and causes the hour hand to rotate once for each 12 rotations of the minute hand. A gear profile optimized for wooden clocks will go a long way towards reducing friction and building a truly satisfying project.
I liked the idea of a free standing frame so much, that I went ahead and designed my own frame that could be aesthetically pleasing and complement the clock gears without competing with them. In clock building your starting point is your pendulum length, it will dictate your BPH which will determine to a degree what tooth counts you can/will use. The clock is geared so that the center arbor turns once per hour; carrying the minute hand. It is worth noting that the original laser cut design actually sealed the cut faces whilst cutting.
The Sextus kit which I have just acquired is the first time I have been faced with the challenge of transforming the appearance of the plywood frame and pendula into what is conventionally accepted as show” wood. All non moving/contacting parts (frame, hands, dial etc.) you can treat as you wish, on plywood I use an acrylic coloured varnish and on solid wood tung oil.
Because of the precision required in cutting and sanding the teeth of the gears, escapement wheel, and other parts, making even a simple wooden clock demands access to power tools and a woodshop. If you have a wide kerf on your laser you may need to make the pallets a couple thousandths larger and make the gear 4 or 5 thousandths larger. Gear: Clock gears are actually made of four parts: the wheel, the arbor, the pinion, and the pivot. The reason I used it was that I was looking for a free, easy to use program, that had certain functions that made designing the gears easy.
Carefully sand the outer parts of the pallet where they meet the escape wheel and lube: I found this makes the clock run smoother. What I had in mind was a clock with a symmetrical dial and a day of the month dial. The clock instructions suggested sanding the mechanical parts with progressively finer grits of sandpaper: from 150, to 220, to 400, and finally 600. Makes our family appreciate a mantel clock built by an ancestor by hand, lovely chimes and workmanship. Using a spray adhesive, carefully glue your plans to the wood, taking care there are no air bubbles. If the clock is running fast, slide the bob down the pendulum, and up if it’s running slow.