Refined Plans for the Escape Wheel
Cutting a proper escape wheel is a very difficult aspect of this escapement kit. It almost has to
be perfect in order to work. Some error in the cutting of this can be compensated for by
adjusting the threaded screws in the escapment-pallet holder, but not all. You'll just have
to watch your completed escapement and see how it behaves, and what is causing
it to skip teeth, or jam up altogether. Many times, you'll have to simply
toss your escape wheel and cut another one.
Here we present an alternate set of plans for making an escape wheel that seems to produce
better results. The idea of these "better plans" is to design and cut a wheel that is just
a bit too large, then to carefully sand it down to the proper size. Sanding appears to be
a better route to obtaining an exact form, than cutting (everyone probably knows this already--we didn't).
We also use a geometric construction to draw out the teeth positions, instead of a protractor.
I. Draw out tooth positions
First, get a compass and set it to 1 14/16" like this
then trace out a circle of this radius
Next, draw a diameter of the circle (a straight line through the center),
and set the compass to the diameter of the circle (point to point where you diameter
line touches the circle).
Next set the center of the compass at each diameter/circle intersection point,and sweep
out two arcs below the circle (one with the center at each intersection point).
Draw a long line that goes through both the center of the circle and the intersection
point of the two arcs. This should be another diameter of the circle that is perpendicular
to the other diameter line.
Next, set the center of the compass as shown, and set the span of the compass to the radius of the circle
(that is, set the point on a diameter/circle intersection point, and the drawing end on the center).
Sweep out a long arc like this
Move the compass point to all diameter/circle intersection points and sweep all four arcs, until you have
a "clover" pattern like this
Draw long lines through the center of the circle and intersection points
of the "clover leaves" and the circle like this:
Now set the compass to 1 1/4",
and draw an inner circle like this
Outline the escape wheel teeth by connecting alternate points that intersect the inner and outer circles,
Keep drawing until your design looks like this
Pretty cool with all of the lines, no?
Cut off excess wood
II. Cut out the teeth
Now, starting cutting out the teeth. But here's the emphasis here: Do not cut ON your lines. Cut OUTSIDE OF
In other words, cut in such a way that your escape wheel and teeth will be too big.
Here we've cut our first 6 teeth. Notice how the pencil lines are still visible.
Finish cutting all teeth in this "outside of the lines" manner.
III. Work to make the escape wheel dimensions more exact
A. Mark out exact teeth diameter
Now, set the compass span to 1 3/4".
Trace a circle all the way around the teeth. Since your escape wheel is "too big," you should be
able to sketch out parts of a circle on the tips of all teeth like this
this. Notice the small arcs near the ends of the teeth.
B. Start sanding
Now, go to the sander, and carefully sand down all teeth until the pencil lines just disappear. Start
on a straight side of a given tooth that is along the diameter of the wheel. Here is a tooth
as we go to the sander
and after we're done sanding.
Next sand down the sloped side of the tooth. As you sand, you should see the tooth size slowly approach and
appear to "eat up" the small circular arc on the tip of the tooth. Stop sanding just as the circular arc
Here's another "BEFORE"
When done, all tip to tip distances of opposite teeth should measure 3.5".
IV. Final look
And here's your finished escape wheel:
The "sanding to the lines" technique seems to produce a much more symmetrical escape wheel, with teeth
that are all the same size.
We've had much better luck getting it to "tick and tock" in the escapement.