Workshop Hints
Brocot Escapement
The British Horological Institute has provided a digest based on e-mails sent to the Clock/Clockers mailing lists on the Internet. The information here does not necessarily indicate a method approved by the BHI, we are only publishing this digest so that others can decide for themselves whether the methods listed below will suit them.
Note: click on any image to see larger view
Based on E-mails from: Zelke Miers, Robert Psurny Jr., Rob Beaver.
Fitting New pallet stones
The following is one method of replacing broken or missing pallet pins in a Brocot style visible pallet movement. It should be noted that if it is possible, the position of the flats on the old pallets should be marked on the pallet arms before you remove the old pallets. This will save a lot of time later when repositioning the new pallet(s).
- To stop the pallet stones falling through the pallet arms during installation, put a small blob of shellac at the back of the hole in the pallet arm.
- Slot in the pallet stones into the arm and visually line the flats up, either with the marks you made earlier or in a position similar to the diagram above.
- Gent
ly hold the arm and melt the shellac so that it runs around the pallet stones from the back. You may need to add some more shellac at this point. - Now comes the trial and error bit, fit the pallets to the clock, manually actuate the escapement and not any errors in the pallet stone's positions. Remove the pallets and adjust the stones by gently heating the shellac until it's semi-fluid. Note: correctly set pallet stones will not give any recoil to the escapement. If there is recoil the pallets are set wrong.
The pallets should be set in such a way that the tips of the wheel teeth fall at or above, but never below the centres of the curved surfaces
Troubleshooting Hints
Possible problems with this escapement are:-
- Loose pallets. This can happen if the shellac is not quite right. This will show up as the clock going off beat.
- Incorrect alignment of the pallets. This will cause loss of power. The most obvious way that this will show itself is that the pallet arm will have some recoil on either the entry or exit pallet. Remember this escapement is a deadbeat escapement show it should have no recoil.
