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If a clock has a heart this is where it lies. The escapement is the source of that soothing (or annoying) tic-tock. The interaction of the escape wheel and verge giving life to the clock by pushing the pendulum and keeping the clock running.
New verges come from the factory unadjusted and can be a bit rough. Sometimes you can put them on the movement and they work fine. Quite often they need to be grinded or bent or both. This is a skill that many clock repair-persons don’t learn until they have been repairing for a couple of years. I had a phone conversation with a fellow who was in the clock business for many years. He proudly told me that he know how to grind a verge. This led me to believe two things: It was something he did not know how to do for some time and it was something many clock repair people do not know how to do at all. I think the cause of this is not because it is a difficult process but all of the information I have seen is very technical. The diagrams deal with how many degrees the tooth and the pallet are related with. Lots of lines and angles are involved with the relationships. I learned this skill from a very experienced clock repair-person who knows nothing about the science of the escapement but everything about how the verge works. It was a secret he held closely and I was fortunate enough to have him teach it to me. He knew it was valuable information and I paid him for it.
I will not be able to translate all of the information to you in words but I might be able to give you the background you need to learn the process.
This type escapement is known as “recoil (see the left photo at the bottom of this page). It is named recoil because the escape wheel will be pushed slightly backwards (recoil) as the pendulum swings past the center line and up. This is obviously not the most efficient system as power is lost as the pendulum swings against the power of the escape wheel. Therefore these clocks were overpowered with a very strong mainspring (.018” thick in most cases). They are inefficient in other ways such as large gears and pivots. This does not in any way make them less desirable. In fact these movements can run long after dirt and wear take their toll.
The verge has two functions: 1) To allow the escape wheel teeth to pass at controlled intervals. 2) To give the pendulum a small push (impulse) each time it swings (both directions). This is the power to keep the pendulum swinging. Remember you only need to replace the power that is lost by the upswing of the pendulum against gravity after it passes the center point. The trick, if there is one, is to achieve both of these at the same time because adjusting for one will affect the other.
I start with the angle then work on the spacing of the pallets. The escape wheel tooth should hit the verge at a 45 degree angle. Place the verge next to the escape wheel and see if the teeth will push the pallets in a way that will transfer power to the pendulum.
Before bending a pallet it needs to be softened. Use a simple butane torch (less than $10.00 at a hardware store) to heat up the area to be bent, red hot, then let it cool slowly. When you have finished all of your adjustments heat the entire verge red-hot and quickly quench it in oil. This will harden the surfaces and slow down the wear from running the clock.
Leave the 90 degree angle where it is and bend (if bending is necessary) the smaller angle to that the escape wheel teeth will push against it. Each tooth needs to ride on the surface long enough to give a good impulse.
Recoil escapements should be set up so that the escape wheel tooth catches a distance ˝ a tooth length from the pallet tip. After the recoil, the pendulum reverses direction and swings down toward the center-line. This is the part of the motion that the escape wheel puts power into the pendulum. Think of it this way: When you push a person on a swing you push them as they are going down. Clock works are the same. It is much harder to push the pendulum as it is going up. After the pendulum passes the center point the escape wheel drops a tooth, recoil occurs in the up swing after the pendulum has gained enough momentum to carry out the motion.
Adjusting the pallet
Should I bend the pallet?
This is done to get the correct angle for the tooth to push the pendulum. Imagine the escape wheel turning and how the power will push the pallet as it slides toward the tip. The angle should be so that the tooth easily slides across and off. Not pushing directly down on the pallet. Do not bend the right angle side of the pallet, only the side with a smaller angle.
How long should a pallet be?
We don’t really know the answer to this when we are fitting a new verge to a clock. Grinding the tip of a pallet is done to open up the distance between the pallets and fit the correct number of teeth between them. As you grind the pallet be sure to keep the angle of the cut as it was originally. If you change the angle you may cause problems. If the angle is too narrow the teeth may not fit between the pallets as the pendulum swings. If it is too narrow the pallet may wear out prematurely. Also keep the edge square. The verge is on a loose fit and it can move slightly in and out. If the face of the pallet is not square the adjustments will change as the verge moves on its pivot.
Grinding the pallet will allow the teeth to leave the surface earlier, this affects the other side. The next tooth to come in contact with the other pallet will get there sooner. You may not have the ˝ tooth depth we want. The verge can be moved in toward the escape wheel if necessary to correct this.
1. Soften the verge by heating to red hot and letting it air cool slowly.
2. Work on the angle by bending the side with the small angle, not the right angle side.
3. Do your grinding, if necessary.
4. Harden the verge by heating it red hot and quenching it in oil.
As I said, this is not and easy, cut and dry process but perhaps I have helped remove some of the mystery.
Recoil escapement Click here to go to our verges page Dead beat escapement