Introduction: Wooden Gear Banjo Clock
This is a 1923 Claraphone banjo that i bought on ebay.There wasnt a whole lot there,just the neck and drum, plus a few of the metal bits and pieces, and only three of the tuners with a finish that only 90 years could apply. The total length is about 21 inches and the drum is about 6 inches in diameter. I made the clock out of scraps of black walnut veneer and super glue, lots of super glue. It has an hour hand, a minute hand and a seconds hand, it shows am/pm and days of the week. The clock is powered with a battery feeding an electromagnet that is turned on and off by a sliding brass switch. Instead of a regular pendulum, it has a pendulum wheel that has a permanent magnet mounted to it that reacts with the electromagnet making the pendulum wheel rotate back and forth, thus driving the clock. You can build a wooden gear clock any way you want, it helps to think outside the box, or in this case inside a 6 inch wooden cylinder.The gear train is pretty much standard, there are a few changes that i will explain later. If you want to know more about the math of a wooden gear clock this site http://garysclocks.sawdustcorner.com will explain things in detail, you will find a wealth of information. If you want to build your own clock this site http://lisaboyer.com is one of several sites that has plans along with other stuff. This is how I built this one.
Step 1: Tools and Materials
Tools: scrollsaw, drillpress, hand drill, 1/16 through 1/2 inch drillbits, forsner drill bits, small srewdrivers, flat and phillips, dustmask, voltmeter, sharp knife, dremel tool, soldering iron, pliers, wire cutters, allen wrenches, 120 grit to 600 grit sand paper, wax paper, two ceramic tiles about 8 inches square and a twenty pound weight ,small paint brushes, box fan.
Materials: black walnut veneer, super glue, 1/16 to 1/4 brass tubing, 1/4 x 1/32 thick brass flat bar, small brass and stainless screws, 3/16 stainless steel tubing, about 1/8 stainless steel welding rod, stainless steel mig wire, 3/16 mild steel round bar,1/4 spring steel flat rod, I used some broken band saw blade with the teeth ground off, solder, and wire, magnet wire, some very small sealed bearings, 1/8 and 3/16 inside diameter, I found these on ebay under micro bearings, very small rare earth magnets, also got these from ebay but radio shack has some too, white and maze colored paint, 1/4 dowel pegs, lead fishing wieghts.
Step 2: Planning
A lot of wooden gear clocks have a 30 tooth escape wheel with an 8 tooth pinion, that is regulated with a pendulum about 39 centimeters long, then a 60 tooth second wheel with an 8 tooth pinion and a 64 tooth center wheel, which is called the drive train, and is usually driven by a coilspring or falling wieghts somewhere close to the center wheel. Instead of a 30 tooth escape wheel, I have a 60 tooth ratchet wheel that is driven by a pendulum wheel. Then we have a 10 tooth pinion, with a 32 tooth wheel on top of it, and a 30 tooth wheel with an 8 tooth pinion attached to the top of it, this is called the dial train, and most of the time the gears are fairly large, I am working in an area of only 6 inches, I want the center wheel in the center with a shaft going from front to back, that means that any of the wheels can be no larger than 3 inches in diameter. I got my gear drawings from a site called, http://emachineshop.com,they have an area where their program will draw you a gear, you choose how many teeth, the pitch diameter and the center hole diameter, the program draws the gear, you send it to your printer, then glue the paper to a piece of wood and cut it out on the scroll saw .
Step 3: Gear Construction
A lot of poeple who make wooden gear clocks use baltic birch plywood, I made all of my plywood because I just happened to have all this scrap black walnut veneer lying around, and used super glue for pretty much everything. I tried to alternate the grain when gluing the layers together and when making gears I use a whole piece and at least 4 layers for each gear. I would glue one layer at a time, clamping it between some pieces of wax paper and two pieces of ceramic tile with a 20 pound weight on top of it . Once I have all the layers glued together, I apply the pattern using super glue for this also.
I used super glue for a few reasons, super glue dries fairly quickly, it soaks into the wood somewhat and stabalizes it so it doesnt splinter as much, you can use it along with some sawdust to fill in a hole, or fix a broken gear tooth very quickly, and you can use it as a final coating, after a couple of coats it becomes very hard and can be sanded and polished to a high shine, its like coating the wood in glass.
Step 4: Gear Truing
One of the most important and difficult steps in making a clock, is drilling the hole in the center of the gear and drilling it straight. I have not been able to do it yet, so I cheat. I drill the hole first and as Im cutting the teeth, I leave a little bit of wood on the tips, then I set up a pivot block for the gear to spin on, then I sand off the extra wood, by spinning the gear against a small drum sander on the drill press. Im sure there are better ways but thats what Ive done so far.
Getting the hole straight starts with fine tuning the table of the drillpress and holding a piece of wood flat as I can on the table, then I drill a hole the same size as the axle, I do every thing I can to get this hole straight, then I push the axle in the hole, put the gear on the axle with the low side of the gear barely touching the wood, spin the gear with the axle remaining still to make sure Ive found the low side and mark it, I redrill the hole slightly rocking the drill bit towards the low side mark, once i feel like the gear is 90 degrees of the axle i glue it.
Step 5: Gear Setup
The front and back plates as well as the face plate, were made with small random shaped scraps glued together in kind of a choatic brick pattern. I tried to have the grain facing in all diffrent directions and used at least 3 layers for these. I decided that all the other gears would circle around the center wheel. Using a protractor I started by drawing a couple of circles on a piece of paper, the inside circle would be a little larger than the center wheel, the outside circle would be about an inch larger than the inside circle, then I glued the pieces of of veneer together, basicly covering the circles, I dont glue all this to the paper, becacse I like to see both sides as Im making these pieces, the circles are drawn just as a rough guide. To get the gears spaced right: all of the gear axles are 1/8 hollow brass tubes, and a 3/32 drillbit fits inside of the tube, so I would place the gears on one plate as close to each other as I thought they needed to be, then slip the drill bit in the tube and drill a slight hole in the plate, then remove everything and drill the final hole. Once I have all the holes in one plate, I use it as a pattern for the other plate. Using the 3/32 holes as a guild, I then drill out the holes with a 1/4 forsner bit, just deep enough for the micro bearings to set into.
Step 6: Making the Clock Run
As most clocks are driven somewhere around the center wheel and regulated with a pendulum rod through the escape wheel, my clock is driven and regulated using a pendulum wheel, its the machanical connection between the electromagnet and the drive train. Its about 5 1/2 inches in diameter, and made with 6 layers of veneer. It has permanant magnets mounted to it that are repeled by an electromagnet. I used pieces of stainless steel mig wire to operate a sliding brass switch and turn the 60 tooth ratchet wheel. I drilled 1/4 holes around the wheel to make it lighter and to balance it by using lead fishing wieghts.The permanant magnet and switch limit rods are mounted on pieces of 1/4 dowel which can be moved around to different holes as needed.
Step 7: Powering Your Clock
This clock is powered by a simple electromagnet, its made with the veneer, a piece of 3/16 steel rod and magnet wire ,it is turned on and off by a sliding brass switch, thats made from a piece of 3/16 brass tube and 1/4 x1/32 brass flat bar. One wire from the electromagnet is connected to one side of the switch, the other wire goes to the negative of the battery, and the other side of the switch has a wire that goes to the positive side of the battery. I didnt really count the turns of wire, I just kept winding until it was about as big as the end caps.
Step 8: Options
After i made all the gears that it needs to be a clock, I noticed there was a lot of empty space still left inside the drum of the banjo, I wanted some kind of symetry to the gear train, so I made a set of gears that show am/pm and days of the week, also I thought it would be cool to have a wooden gear clock with these two extra options. And its all powered by the dial train.
Step 9: What Not to Do
Dont breath the fumes or dust when cutting or sanding a piece of wood with super glue on it, the fumes are fairly acidic and will burn your eyes and irratate your sinuses, Im sure its just not good for you, try to work in a well ventalated place. I wear a dust mask and set up a box fan on medium, blowing the dust away from me.
Water based glue:
Dont use a water based glue to attach the patterns to a piece of wood, the water in the glue will distort the paper and you will end up with a gear shaped like an egg. Also try not to use a photocopied gear either,sometimes the picture gets distorted in the process.
Days of the week:
If you happen to build a clock inside a little bitty fairly old banjo and you go through the trouble of adding a wheel in it that tells the days of the week, and you take a soldering iron and burn in the letters on that wheel that represents those days and then fill those burned lines up with paint and cover it with super glue try to remember what direction that wheel turns before you do that.
Really big magnetic reed switch:
If you build a clock that uses a really big magnetic reed switch and its the only one you got , try not to break it.