Fabrication of grasshopper escapement
assemblies - January 2009
Photos show the beginnings of the grasshopper support rings. These rings
will attached the individual grasshopper pallets to the balances. They are adjustable to
about 30 degrees to enable changing the angle and depthing of the escapement though a
small worm acting upon a toothed sector on the ring. When the assembly was attached to the
end of the balance it looked too thick, third photo, and efforts were made to thin the
design.
The final results are below. Notice also the worm was tapered to give it a
slimmer look too.
Now begins the grasshopper composer springs. These will each contain a
jeweled antifriction wheel. This design is experimental and will manipulate the
grasshopper pallets against the force of gravity. In conventional designs gravity is used
as an assist. It is uncertain at this time whether this design will work, but it is a
beautiful complication so it will be tried. The first photo shows the slotting of a tiny
cheese head screw while the other two show the milling of the springs.
The last photo shows an EDM machine that will be used in the making of the
antifriction wheels. Nearly all of the wheels on this movement are cut by hand on a
jeweler's saw, but these are very small, and there will be a set of four identical so that
this method of manufacture was chosen.
The completed wheel as it emerges from the EDM machine. Next a matchstick
shown for size comparison and finally a shot showing the insertion of the wheel arbor.
Here we see the size comparison of the composer antifriction wheel as
compared to one of the main wheels in the movement. Next the two composer springs are
positioned and then a view of one of the composer springs' jeweled chaton pivots.
The first photo shows the beginnings of the grasshopper pivot cages. Next
two show the insertion of the lower and then upper pallet jewels. These are specially
shaped according to a design by the leading British expert on grasshopper escapements, Mr.
Peter Hastings. This jewel shape as well as the rest of the grasshopper pallet design will
prevent a common flaw in the grasshopper design. Conventional grasshopper escapements are
susceptible to tripping and in a worst case, an escapement runaway. All of the jewels
which are not of the round pivot type are custom cut and polished in house, (see video).
We now see the beginnings of the actual pallets.
The final shape of the upper pallets are shown as well as close up of the
jeweled pivots.
Below is a close up of the upper pallet jewels. Notice the graceful way
the neck of the pallet joins the area where the jewels are held along with the decorative
curl. Most fabricators would have made this part in a two dimensional fashion, skipping
the extra work involved in making this exceptional detail. This extra effort is present
throughout the design and manufacture of this clock. Next we see the two pallets
attached to their respective composer springs. Last photo shows the jeweled flats upon
which the antifriction wheels ride. All sliding and other surfaces similar to this are
jeweled.
The completed right hand escapement assembly and it's insertion on the
movement.
