Cogworks Wooden Works Clock Movement
Our wooden works clock movement is styled after Jesse Emory's 30 hour movement. Emory's design had a clear record of good timekeeping and reliable performance. Many of the six Emory movements we looked at still worked and looked in excellent condition. They out performed many brass clocks before maintenance intervals.The 30 hour movement was called a pull up movement, because instead of winding with a key one opened the case door and pulled down on a cord pull, this in turn raised the time or strike weight.
When designing our wooden works clock movement, we made some improvements to that of Jesse Emory's. We thought that some people may need a little help to wind the clock so we incorporated a gadget that authentically replicates this hand motion. This gadget simply sits in the bottom of the case and attaches to the manual pull downs. It does not interfere with the operation of the movement. However, if one wants to hand wind the clock, one can disconnect the winder cords from the manual pull downs. The clock is rewound after the strike of 12, at midnight, everyday. Because of Emory's unique design of gravity clicks, the rewinding process is hardly audible but does make a visual treat if looking through the bonnet glass windows. The winder uses alkaline cells which will last from 5-7 years before needing replacement.
Features of the movement are detailed below:
The wooden gears in a Jesse Emory clock are significantly better than most wooden works clocks gears of the period. Emory's style of making gears was unique for the period. Some trademarks of his wooden gearing are defined below:
- Most gears are wide from 1/2" to 3/4"
- All gears are made from hard maple.
- Most gears are undercut and scribed both sides.
- The teeth have rounded ends which lowers friction and increases strength therefore adding to their beauty.
- All the gears are "raked' and of true historical wooden works form. No modern out of place tooth profiles.
- All metalwork is finely crafted and polished.
- The finish is super smooth.
The Center Wheel
One of the main gears in a Cogworks wooden works clock is the "center wheel". The gear is made in a very similar style to that of Jesse Emory and meets all the above trademarks of Emory's work. However, we did take the liberty of making improvements as outlined below:
- Only quarter sawn hard maple is used - halves dimensional changes with humidity. No plywood or glued up hardwood ply is used.
- All maple is stabilized at 42% & 70degF relative humidity, at least 4 weeks, prior to machining, this improves dimensional reliability and allows us to check the dimensions of all parts consistently.
- Only the best stainless steel hardened ground and polished pivots are used. All metal used is stainless steel.
- On all Cogworks wooden works pinion shafts an inner shaft made from brass is used, the end of the brass shaft can be seen on center wheel above. Maple is then turned and bored and is then placed over the brass to make the assembly indistinguishable from the all wood original. This allows precision location of all pivots and prevents bowing of the pinion shaft over many decades. It was noticed that a number of Emory's pinion shafts were bowed giving some potential reliability and wear issues over time. This unique Cogworks feature is extremely time consuming especially when it is replicated ten times for all pinion shafts in the movement. All of these shafts are made on our Hardinge HLV-H tool room lathe, one of the best and most accurate lathes around. This extra work is added insurance in order to keep the movement "honest" and true. New England homes, without air conditioning, can be subjected to relative humidity swings of approximately 10% in winter to 95% in summer. When subjected to this humidity cycle the movement is constantly in a state of dimension transformation. Many design features, in the Cogworks movement, allow these dimension changes to go on without creating any problems or stress within parts.
- The pinion shaft ends are polished brass which gives an extremely low coefficient of friction when rubbing against Lignum Vitae. This improves the running and reliability of the clock. Wood against wood has a higher coefficient of friction absorbing more power and wearing quicker.
All these improvements are carried forward to all gearing in our wooden works clocks providing a new benchmark in wooden works clock performance and reliability.
Time Side Gear Train
The time side gear train components in the movement are shown. The front plate and strike side components are removed for clarity. Key points on the high quality construction are discussed below:
- The lower wheel, called the great wheel, has Emory's unique gravity click system for smooth silent rewinding of the movement.
- The next wheel up the chain is the center wheel
- The next wheel up the chain is the third wheel.
- The next wheel up the chain is the fourth wheel.
- The brass escape wheel can also be seen. The recoil anchor shown is from brass with "glass" hard steel inserts soldered in place for long life. The inserts are then highly polished.
- The clock plates are made from quarter sawn maple. The movement has six posts to secure the 3" gap between the plates, 2 more posts than most wooden works movements. The posts are nicely shaped with 3 scribe marks in the center.
- The lignum vitae bushings can also be seen, for lubrication free operation of the movement. Lignum vitae, the heaviest wood in the world, has special lubrication properties that man has not yet managed to synthetically recreate. These bearings, first used by John Harrison, will keep this clock running lubrication free for 300+ years !!!
- Note the brass bearing surface on the end of each wooden arbor, much lower friction than wood on wood.
Tapered Hard Maple Pegs
Tapered hard maple pegs, brass and steel taper pins, all hold the movement together.
The wooden works clockmaker did not need any tools to strip his movement down to investigate a problem.
Long maple pegs work wonderfully to hold the clock plates and dial secure.
Emory Movement Notes of Interest
The Bells !! The Bells !
The Liverpool, England Connection
Jesse Emory originally procured bells from George Ainsworth in Warrington, England. Ainsworth was a brass founder and pinion maker. (c1795-1815). His products included small bells, large bells, pinions and whole 8 day brass movements. Through a middleman Ainsworth's fine products made it over to Boston for purchase by American craftsmen. It is very interesting that all known Emory clocks used this bell.
St. George's Church in Everton, a district of Liverpool, England, was built in 1814 and was the first church building in the world to be constructed substantially from cast iron. Its architect was Thomas Rickman and the cast iron came from the foundry of John Cragg. The church became known as "The Iron Church" and sits on the top of Everton Hill (the site of the original Everton Fire Beacon, built about 1220). It is clearly visible from miles around and provides excellent views over the North End of Liverpool and out beyond the River Mersey to the Wirral and North Wales.The church is 119ft. long and 47ft.wide.The tower is 96ft.high. Its original "chair frame" bell, byAinsworth of Warrington, was restored in 1937. The bell maker used by Emory has great pedigree!
The bell used in the Cogworks tall clock is unfortunately not made by Ainsworth of Warrington. The English bellmaker connection is historically important so we chose the Whitechapel bell foundry of London for our bell. Whitechapel is the oldest manufacturing bell company in England, having been established in 1570. The Whitechapel bells are excellent quality and have a fantastic sound. The bell is brightly polished and we can rotary engrave the bell for that special clock.
Whitechapel's famous bells include the original Liberty Bell (1752), the Great Bell of Montreal, and probably best known of all, Big Ben at the Palace of Westminster, London, England. Cast in 1858, this is the largest bell ever cast at Whitechapel, weighing 13½ tons. To this day, a cross-section of the bell surrounds the entrance door to the Foundry.
The Makers mark
In Emory's works often you will see timing marks to ease assembly. It is interesting that with a few hours training, anybody can strip the Cogworks movement down to all it's component parts.