This page gives some hints about Big Ben and Baby Ben alarm clock repair. For the names of some excellent clock repair books, see the recommended reading page.
Don't use ammonia based cleaner on hairsprings. Use waterless non-ammoniated watch cleaning solution, or use alcohol. Ammoniated cleaners tend to eat away the hairspring material, changing the rate.
I number wheels starting at the main wheel. F and B refer to front or back, and T and A refer to time train and alarm train. For example, T2F refers to the front pivot of the second wheel in the time train (which is the center wheel in a Big Ben or Baby Ben).
After disassembly and cleaning the movement, use a narrow strip of crocus cloth to clean each of the wire pivots (fold the strip around the pivot and rotate the pivot by hand). This will remove oxidation.
The center wheel pivots usually need to be put in a lathe and smoothed with a pivot file, then polished or burnished.
These are my preferred lubricants. There has been controversy about using synthetic motor oil for clocks. My experience, and that of others has show that synthetic motor oil works extremely well for clocks. (References Stephen Nelson and Ken Reindel).
Synthetic motor oil types I use:
Oiling Locations for Big Ben Style 1, 1a, 2 and Loud Alarm Movement:
Use KWM sized bushings, DON'T use Bergeon bushings! Bergeon bushings require a large hole to be reamed, and it looks bad.
I recommend "American System" bushings in KWM sizes (available from the major clock parts suppliers), for the larger bushings such as #13, #21 and #26. I use KWM brand bushings for the small sizes such as #59, #5 and #6.
Many pivot holes in Big and Baby Bens have a curved recess inside the front plate. Especially on a Baby Ben, you will need to recess the inside of the bushings similarly to the original recess, or the endshake may be too little when the movement is cased. I put each bushing in the lathe, and, turning the lathe by hand, first start the recess with a chamfering tool, then finish it with an oil sink cutter. Then I install the bushing in the plate.Big Ben Loud Alarm:
Use "Rubin-Brite" metal polish. Produces best polish on nickel that I've seen.
Take the movement out of the case before using metal polish. Thoroughly wash off all metal polish when done.
Coat old luminous hour and minute hands (style 6 and earlier) with a thin layer of Elmer's glue to help prevent the paint from flaking off during removal and installation. (Old luminous paint gets dried and cracked, and can easily fall off when the hand is disturbed. The thin layer of glue will stabilize the paint.)
Remove movement from case. Bend a brass strip in half and put it over the center arbor between the knob and the back plate. Firmly grasp the center arbor (on top of the brass strip) with Vice-grip pliers. Lever the knob off using 7" diagonal cutters, using the vice grips at the fulcrum.
The regular way of prying off the knob will compress the tension spring, as there is no shoulder on the center arbor. Also, if the movement has an aluminum back plate, it may bend.
The later alarm trip assemblies - the one in which the cam on the trip staff is a steel disc with a cutout, and the trip wheel is steel with a stamped out projection - can be troublesome. I had so much trouble with these parts on a 1970 Big Ben leg model reproduction that I replaced them with the old style trip assembly having the brass finger on the trip staff and a brass trip wheel. This solved the problem of the trip staff being carried around with the trip wheel.
I'm still trying to find a way to make the trip wheel move up and down easier on these steel trip assemblies - please tell me if you have any hints! I've tried polishing the lifting surfaces, and chamfering and smoothing the hole on the trip wheel. You can hold these parts in your hand and tell that the old style works much better than the new style.
The red cement may be dissolved with lacquer thinner to remove the hairspring from the stud. A convenient way to refasten the hairspring to the stud when reassembling the clock is to use orange shellac (in liquid form from a can). This can be removed with denatured alcohol the next time the clock is taken apart.
Jim Galazka has suggested using fingernail polish to glue the hairspring, which is an excellent idea. It is easily available, can be removed easily, and you could probably match the original red color if desired!
Use a pair of Wiha 26810 5.7-Inch Precision Chip Lifters (or similar devices) for the small alarm hand on style 3 through 6 Bens. First, put a dial protector (a business card with a v-slot in it) beneath the hand. Set the clock face up in a stand to hold it securely. With one lifter on each side of the hand engaging with the hand (with the curved part of the lifters resting on the dial protector) press the handles of the lifters inward (to be sure they stay engaged with the hub) and down, and the hand will pop off. (Note: this method works with Bens style 3 through 6 because their alarm hands have a hub which extends to the edge of the hand. Styles 1 and 2 have a small hub, and this method will cause the hand to come off the hub.) Note: this won't work on a style 3 Baby Ben, as the hand has a narrow hub. If the hand pops off the hub. it can be pressed back on.
While the clock is still in the case, remove the winding keys and the bell back. Use a side cutting pliers (about 7 inches long) as a puller. Put a couple strips of wood (to bring the jaws of the cutters just above the knurled part of the knob) as a fulcrum on top of the inner back about 3/4 inch away from the knob, set the side cutters with the jaws below the knurled part of the knob, and press the handles down to make the jaws pull the knob upward. It may take a few tries to get the positioning just right.
Baby Ben trip staff: 2-56. (2-48 up to ca. December 1912).
Baby Ben Style 3 and 4 top case clamp screw: size 3-40; overall length 7/32 inch (5.5 mm), body (threaded part) length 3/16 inch. Head diameter 4.13 mm.
Baby Ben Style 4 bottom case clamp screw: size 3-40; overall length 13/32 inch (10.3 mm), body is 11/32 inches long with 7/32 inches threaded (and some have the entire body length threaded). Head diameter 4.55 mm.
Big Ben Style 1 Case Front Screw: Originals are 1-56 thread, 1-64 will work as a replacement. Round head (except that early examples have square sided flat heads) about 3.55 to 3.59 mm diameter.
Baby Ben Style 1 and 2 Case Front Screw: 1-56 thread, 2.5 to 2.7 mm round head, body length 4 mm (5/32").
Big Ben Style 2 Base Screw: 6-40 thread, 5.5 mm round head (7/32"), body length 5.84 MM (7/32").