New Haven 12 Day Mantel Clock

[PR21]

I purchased this New Haven 12 Day Mantel Clock as a Parts/Repair item to learn with.
I have not found many pictures or details on this movement, so I hope to add what I can.
Upon removing the movement from the case, it was evident that there was excess oil and grime on the movement.
The movement beats for a few seconds when coaxed and stops.

 

[PR21]

Taking the movement apart for inspection and cleaning was complicated by a bent Hand Adjust knob and shaft.
The Hand Adjust mechanism has a gear on the front face that is staked onto a shaft which passes through the movement to the rear Hand Adjusting Knob.
It is necessary to remove the rear knob so that the rear plate can be removed.
There is a spring on the shaft that is locked in place with a cotter pin like wire that must be removed to allow for the middle plate to be removed.

 

[PR21]

I drilled and slit a 3/4 inch dowel to fit over the winding key to serve as a main spring let down device.
Inspection revealed galling damage to the First Wheel Shaft which I imagine was caused by someone gripping the First Wheel Shaft with pliers as a means of releasing the main spring. I don't know of any other cause for the damage to the First Wheel shaft.
The dowel works great as long as the movement is secured in suitable clamp.

 

[Kevin W.]

There are better clocks to learn clock repairing on. I would avoid any with a balance wheel to learn on.Just saying as i dont know your level of repair knowledge and experience.

 

[PR21]

Yes, I agree that balance wheels are not an ideal starting place.
The balance spring is a source of this clock's problems.
The balance spring was found to be distorted but still functioning slightly.
In addition, the balance end shake was high in my estimation - the balance was barely retained by the cone bearings.
I did not get a great picture of the distortion, but a top view of the movement shows it slightly. The spring coil was dipping to either side of the rotation plain.
I found that the balance spring was bent as if the balance wheel had been pulled or fell away from its position with the spring still attached to the stud and regulator.
The spring, removed from stud and regulator, was not flat. The bend in the spring was causing coil distortion when mounted in the stud.
Another issue was the regulator arm being bent away from the rotation plain, as if the regulator had been bent to follow the distorted spring.
I reshaped the spring and straightened the regulator. The attached pictures of the repaired spring were taken prior to mounting on the balance staff.
Now the clock is running and I am working on the accuracy.

 

[PR21]

The main spring arrangement is new to me.
The rear plate is captured between the winding ratchet wheel and the barrel.
The barrel cover plate with gear is staked onto the main spring arbor.
I mildly attempted to disengage the main spring arbor from the main spring without success.
I cleaned this assembly as is and lubricated the spring by lifting the barrel cover plate a little.
I get the impression that servicing this movement was not a high priority in the design.

 

[PR21]

The Wheel Train and Pallet.
There are seven pivots in the front plate.
There are six pivots in the middle plate.
The First Wheel pivots in the rear plate and front plate.
The Second or Center Wheel is captured on the front plate.

 

[PR21]

The Center Wheel is attached to the shaft with something like a compression collet.
The Cannon Pinion looks to be pressed on to the shaft.
I am not familiar with this arrangement, so I am leaving the center wheel assembly as is.
The intermediate wheel shaft is staked on to the front plate - I am not disassembling this either.

 

[PR21]

Timing this movement is on going. Since the balance spring and regulator was misshapen, getting it back in shape requires many disassembly and reassembly of the movement to test. The mechanism is simple and robust, making it an appropriate learning opportunity for me.