Designing Wood Gear Clocks:
One thing that I have gotten into is designing clocks. These are not the usual clock that takes the battery movement. These are clocks that have all the gears cut from Baltic birch plywood and are powered by a weight on a cord. Now when I say that I design them I do mean from the beginning. All the parts are drawn with Corel Draw 9 on the computer. It is a fairly difficult task in some ways but once you figure out the mechanical part it gets easier.
The gear ratio is the main working of the clock. But there are formulas that will figure that out or magazine articles that give you some of the more common ones. I chose to start with one of the more common one of 60,64,8,10,30,32 tooth gears. Once the ratios are established the going is easy. Just make a frame to hold them and mount the gears into it. Well it sounded easy anyway!
Making the gears work was the first step. I acquired all kinds of textbooks, engineer manuals and such to figure that out. I don't really understand the formulas for the pitch angle and all of that yet. But I did conclude that if one gear had 60 teeth and the other had 8 teeth , they had to maintain the same ratio when the shafts turned. So from there I started drawing teeth for the gears. They were fun to draw and I couldn't wait to cut them out and try them. That started into the real mess. The first gear was the easy one, and looked nice. Put when it came to making the one that engaged with it and rotate without jamming , that became a problem. Through trial and error and studying the books they finally worked. After doing my second design of clock I still make gears that don't work the first time. So you just throw them into a box and do another one till it does come out right. More of a trial and error method. But when I get the final one made it works the way it was suppose to in the first place.
After the gears were cut out they needed to be spaced to work properly. I worked on a few different ways to figure that one out too. But I finally designed a jig that allows you to test run the gears till they run smooth. It's just a matter of putting those measurements into the frame after that. You need to design the style of frame you like for the clock too. And make sure that everything fits into it right. I have make a few frames that just don't work right either. Seems like my box of non-working parts keeps getting fuller. Then the clock face has so many possibilities for a design that you could never make enough clocks in a lifetime to do all of them.
It may be a lot of trial and error to design them this way but when they are finished they work. After writing the pattern out I build another one from the pattern. If the pattern doesn't tell you to do it, then you shouldn't have to. So by the time the pattern is written and changed to add all the steps or details forgotten in the first place, it takes awhile to do. I write it over and over again until I am satisfied that it is right. The first one I ended up rewriting or adding to nine times. When it is finally ready for sale you can be assured that it has been tested. But if someone tells me about an error or asks a question I sure add that too.
In all the designing and pattern making is fun to me. But probably not for everyone. First of all you need a good working knowledge of a computer graphic program like Corel Draw. Some mechanical aptitude is real helpful when looking at things and trying to figure out why it doesn't work like you think it should. Then you need to be ready to cut a lot of scrap that doesn't work. And finally be able to write it out so that someone else can follow your directions.
I now have six clocks designed , but I haven't run out of ideas yet. Now I just need to think about starting the next one.
I designed these clocks I used Corel Draw. I did not understand the formulas for
gear design or tooth shapes. So I just drew what looked like a nice gear design
to me. Then drew and tested pinion gears until I found one that worked nice. I
would make one and try it, looking close at it to decide how to reshape the
teeth so it would work better. It took many tries to get some of them done, but
I can say that nobody will be able to put these clocks to a cad program and use
any formulas or functions to duplicate them. They are one time designs that
match up with no other gear. Then some told me they would cut them on a mill
with a gear cutting bit. I knew that met cutting from the side across the gear,
so the front and back had to be the same like you normally see gears. As you can
see I made sure these clock gears will not be cut on a normal gear cutting
machine across the teeth.