3: Drawing the Graham Pallets
Over the escape
wheel, draw two radius lines at 90º to one another. Draw two more lines at 90º to the
radius lines and place them at the edge of the circle. The point where these new lines
intersect is the center of the pallet circle, the radius of which should measure three
inches. Draw the pallet circle about this point. You now have four radius lines. Draw two
more radius lines next to each one, positioned at 3º on either side of each. I chose to
extend all the radius lines.
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Since the escape
wheel rotates clockwise, the entry pallet is on the left side of this drawing. Draw a
horizontal line between the three lines.
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The exit pallet is on the right side: draw a vertical line between the three lines there.
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It is
important to draw the locking faces, which will consist of curves drawn over circles,
such as to preserve the dead-beat nature of the design. Draw two more pallet circles with
diameters of 5.69 and 6.31 inches. Once these lines have been completed, the rest of the
pallet could be drawn any way you wish. I drew the this one by drawing a horizontal line
across the pallet circle, then rotating it by 24º, duplicating it and placing one line 0.25
inches above the center line and the other 0.25 below. I grouped these two lines, duplicated them, flipped them horizontally, and placed one pair on the other side.
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Remove the excess lines to get the result. This is the ideal Graham design as its angles maximize the power transferred from the escape wheel to the
pallets.
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