[graupman]

I am new to making clocks - my most recent project is to design and build a clock primarily of wood, but with some key brass parts and steel bearings.

Since I have no experience in this area I am hoping for some guidance - I have attached a drawing of my escapement design, and I am hoping to get some comments on it. Will it work? What are some potential problems? Have I made any obvious beginner mistakes?

Any suggestions would be appreciated!

[David Walter]

You haven't marked the direction of rotation on the drawing, it looks like it may be anti-clockwise. If that is so I also don't see how it can have no recoil.
You don't mention or indicate the drop of the pin to the escape wheel but you should know all drop is a loss creating a loud "tick' which many like but is undesirable as is a large swing of the pendulum.

Clocks have been made with the pallets directly built into the pendulums but there is always the risk damage should the clock receive a knock.

[graupman]

You are correct - the rotation is anti-clockwise. This could be my misunderstanding of terms... I was under the impression that recoil was a slight backward motion of the escape wheel during each cycle. This is what I had intended by that term. The wheel will be stationary whenever the pendulum is past approximately 1.0 degree in either direction, and will move anti-clockwise from -1.0 to 1.0 degrees. Am I understanding this term correctly?

Over the course of one swing, the escape wheel will move 12 degrees. 2.5 degrees of that 12 will be "drop" to allow for the pin to clear the next tooth. I read that this was a waste of energy, but did not affect the accuracy of the clock. Is this correct? If that's the case I am willing to accept the loss, but if accuracy is affected I might have to rethink this a bit...

I am also somewhat less concerned about damage if it does occur on rare occasions. I am assuming that since the parts will be made from soft woods they will wear relatively quickly. Since they parts will be laser cut it will be easy to produce several identical escape wheels and gears that can be replaced as needed.

Thank you for the advice! I am really enjoying this process.

[David Walter]

Yes, I think you have understood recoil correctly, but to be clear recoil takes place after after the drop and when the wheel is locked.
As you have it drawn and with anti-clockwise rotation of the escape wheel you will have recoil after the locking, unless the locking takes place towards the center of the wheel and past the knuckle of the tooth even then I am not sure. This, if it works will need the large angle of swing to operate. The next problem is with a small pin and so much drop there is little impulse available to keep it running.
The main fault with too much drop is that the drop is at the expense of impulse which effects the performance of the escapement

[rayfrank]

This one is the nice concept about the escapement design and the pendulum for the watch.I like here the theory used here to understand the concept is very nice and easily understand.I am also like to say that the graph and the figure is used here to understand the pendulum concept is nice to know about this thing.

[graupman]

The loss of impulse brings up another question that I have been wrestling with - how to predict how much power the clock will require to operate.

I have constructed a pendulum with a simple non-aerodynamic weight and fixed a slider and brass rod at the point where the escape wheel would be (to mimic losses from the brass pin rolling along the escape wheel). With this setup I counted 135 cycles before the pendulum swing lost 36% (1/e) of its energy (percentage calculated by height of the bob, not angle of swing). Assuming exponential decay that is a loss of 0.75% per cycle and a Q-factor of 850.

With my current setup the clock will have enough power to drive a 3 lb pendulum assuming 10% loss per shaft and gear pair and a 30% loss of energy where the brass pin rolls along the escape wheel. I am assuming the potential energy lost by the pendulum equals the work added per cycle by the escape wheel.

Is this the right way to go about it or are my assumptions flawed?

Also, I have attached a more detailed drawing of the escape wheel tooth to better illustrate the motion of the pendulum.