Clock Parts & Repair Blog

I have a howard miller grandfather clock it keeps great time however when turn on the striker and turn on the striker for the chimes it continues to chime and will not stop chiming and the wieght naturallly goes down fast any suggestions.
Response from norkro.com
There are a series of levers, cams and gears that must be in sync in order for the chime or strike to start and stop. First you must understand the function of these so that you can troubleshoot your problem. Different movements use different methods for stopping the chime but I will try to give you enough information here for you to solve your problem.
The chime and the strike are two different functions and they are totally seperate of each other. Each has its own gear train and levers. The chime runs every 15 minutes and plays the music. The strike counts the hours and should start after the chime plays the longest part of its song. I keep these two seperate.
Chime: The chime gear train is located on the right side as you face the front of the movement. It almost always uses the heaviest weight. Placing the wrong weight here may cause it to not run fast enough or not at all. There is a star gear at the base of the handshaft with 4 points on it (representing the 1/4 hour). One point is usually higher than the other 3. This is the hour chime and causes the chime to sync to the top of the hour.
As the minute hand reaches one of the quarter hours it starts to lift the chime lever. As this happens it realeases a pin on one of the gears near the top of its own gear train. This gear spins about 1/2 turn before the gear train is stopped by this or another lever. This is called the warning and is a set up to the 1/4 hour chime. When the minute hand reaches the 1/4 hour the lever drops off of the star gear and the chimes play music. The chimes should play their appropriate song section and then stop. While this song is playing a cam holds up the chime levers keeping them from catching the stop pin on the gear mentioned earlier. This cam has 4 sections on it. Each section represents one quarter of an hour. The first one is the smallest for playing the shortest song at 15 minutes after the hour. Each 1/4 hour has a longer song leading up to the hour. When this cam rotates through the longest section (playing the hour chime) it has a raised tip. This raised area lifts the strike lever causing the strike to pass through its own warning and then starts the strike when it drops down.
Here is the trick to stopping the chime music: Two thing must happen at the same time. When the lever drops between the sections of the chime cam the chime should stop. You need to look at the movement and figure out what stops your chime. It will either be a pin on one of the gears near the top of the chime train or it may be another cam. Most likely your movement uses a small cam on the front of the movement to sop the chime. this cam will be about 3/8? in diameter and have one slice out of it similar to a piece of pizza being cut out. A hook lever would drop into it and catch the flat side stopping the chime gear train. This cam could be a round disc with a pin on the back side. Often the pin breaks off (espically on movements made by Hermle). We can sell you a new cam if this is the case. If nothing is broken the lever may be sluggish (not dropping fast enough to stop the gear train befor it starts lifting again) or it could by out of sync (gears not in position to be stopped while the levers are in the shallows of the chime cam).
If it is a pin on a gear the pin may be broken off or the gear train might be out of sync. Look at the chime levers to see if they have a tab that goes into a hole in the plate to catch a pin. Look at the two top gears on the chime side and see if there is a small pin broken off of one of them.
Strike train:
The strike train is simplier than the chime in that it plays a single tone and only runs on the hour. As stated above it performs a warning to set up the strike. The strike uses a rack to count the hours. This rack drops further for the higher hours. At one o?clock it should drop into the first section allowing only one strike then its lever will drop off the edge of the rack and stop the strike. As the hours progress the rack drops lower adding one more strike each hour. At 12 o?clock the rack drops far enough for the hour to strike 12 times. A rotating cam with a small pin lifts the rack one tooth each time the clock strikes. Eventually the rack is lifted high enough for the lever to drop down by the side of the rack. When the strike lever is down off of the rack the strike should not be running. This lever may catch an edge of a cam or a pin on a gear to stop the gears from turning. If this pin is broken off the rack will not be lifted and it will not stop striking. You can lift the rack with your finger and see if the strike stops when the lever is down off of the rack.

Is there an drawing of what to oil on a grandmother clock?

Do I remove the hands and face to do this?

Response from Norkro.com

I don’t have any drawings but I can tell you the important oiling spots:

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Nearly all mechanical clocks use the escape wheel/verge setup to operate. This setup serves two functions: It allows only one gear tooth to pass at a time giving us the ability to regulate the speed of the clock through pendulum lengh, a hairspring, or in the case of an anniversary clock it is the distance of the pendulum balls from the center of the pendulum. The other function is to keep the clock running. The escape wheel tooth pushes the verge. This impulse pushes the pendulum or whatever device the clock has to control the timekeeping to keep it running. Take note that this impulse can be very small. It only needs to push enough power to replace whatever is lost due to gravity or friction. Below is a breakdown of a 400 day clock escapement:

There is a fork attached to the suspension spring near the top.

This fork moves left and right ans the pendulum rotates.

The fork guides a pin sticking directly from the top of the verge.

The verge rocks back and forth letting one tooth of the escape wheel pass each time the pendulum rotates one direction.

The escape wheel pushes the verge (this is called an impulse) transferring power to the fork which twists the suspension spring in the direction that the pendulum is rotating.

This action keeps the pendulum rotating.

 Original message

I just picked up an old clock at an antique shop that we just love.  Unfortunately it doesn’t work.  I opened it up and it has a Lashire Type SS-2 electric movement inside. I oiled it and was able to get the clock to run by plugging it in and giving the gear a spin with my hand.  But…if it is unplugged, it will not start again unless I spin the gear.

I see that you sell Lanshire movements, but we really don’t want to spend another $30 plus dollars to get a new electric motor (since the gears still work)…so my next option looks like a new battery operated movement.

The current movement has three mounting screws that hold the Lanshire movement into the clock.  Do you have a battery operated movement that I might be able to place into this clock and maybe even use the same hands? (assuming I can figure out how to completely disassemble the clock to that I can remove the movement that is in there

Response 

I have done this replacement before and can tell you what is involved.

Pull the hands off of the clock

You will take the three nuts off of the motor mount posts and remove the motor.

When you remove the motor all of the gears will fall out, this will leave a space large enough for the mini quartz movement to fit in.

I use our #100010 mini quartz movement because it has the shortest shaft.

You may need to make the hole in the clock face larger to accept the threaded portion of the movement

The movement comes with a flat washer that goes over the handshaft on the front so it’s ok if you are not perfect in opening the hole. the washer will cover up about 1/8″ all the way around the hole.

You can put the movement through the hole, put on the flat washer and mounting nut.

Your original hands will not fit on the movement unless you make the holes in them larger. You can do this with a needle file. The hour hand hole has to be just the right size so go slowly. It is a press-on hand. If the hole is too large the hand will be loose. You can’t use your original second hand unless you purchase a second hand from us and remove the mounting tube from it and gluse it to your original. It is easier to just use on of our second hands. In fact the easiest way to do this is by replacing all three hands with new ones. If your clock is about 4″ across I use our 1-7/8″ black sword hands and a 1-7/16″ second hand.

Important note: If your clock has glass on the front you will need to get to the setter on the back of the movement to set the time. Many Lanshire movements have a solid backplate. If you use this backplate to hole the movement in the case you will need to remove the screws or nuts to get inside whenever you change the battery or the time.

You can see the movement at:

http://www.norkro.com/index_files/page0014.htm

The hands are at:

http://www.norkro.com/index_files/page0021.htm

Sometimes a clock repair person will need to put a hole in a suspension spring. Universal suspension springs come with a dimple in them but still might fall through the post of an American style movement. In this case we punch a small hole and put a piece of brass wire through the hole with a twist at the top. Many of the originals came this way from the factory.

You will break the spring if you try to drill it. I use a punch. I have a block with various sizes of holes in it (This is called a staking block). I use steel pivot wire just slightly smaller than the hole I choose.  I use a nail shaped punch to put a dimple in the spring (unless there is already a dimple there) where I want the hole. Then line up the dimple with the hole and tap the wire through it. This makes a clean hole and rarely cracks the spring.

The weights are probably about 2-3/4 to 3-1/4  pounds each. They are generally about 4″ long and 1-5/8″ diameter. They consist of brass tubes with lead filler. The caps are usually simple flat discs. More expensive regulators have weight shells that are embossed. The real desireable onese will be etched by hand. If you are real lucky the design on the weight shells will match the center of the dial.

For many years it has been my desire to publish a question and answer forum where customers can find information about clock parts and repair. Earlier this month I launched my blog in so that anyone can join in. I postesd some recent correspondence I have had with some customers. I did not include any names or email addresses, just the questions and answers. I also added some commonly requested infromation.
This blog will continue to be a work in progress and hopefully it will grow to include just about anything you need to know about clock parts and repair. I invite anyone interested in clocks to post questions, answers and to comment on any posting that is up there. There is a simple sign in process that enables you to add your comments or post a question. We will not publish, sell, trade or use your personal information in any way.
Please bookmark my new blog, have a look at it and be a contributor by posting a question or comment.
Thanks, Michael
owner: norkro.com

————– Original message ————–

 Is it possible to grind down a 3-3/4″ convex glass to 3-11/16″ without damaging it? Please advise.

I have ground glass down many times. I have used a disc sander and a diamond disc attached to a lathe. Either method will work. They do fracture the glass around the edges as the glass is removed. It is not a real clean way of doing it but if the glass is mounted behind a bezel it works fine.

It is very easy to damage the glass. If you don’t keep turning the glass as you are grinding it will get too hot and break. Also, it is easy to slip and scratch the glass with the disc.

the only way to do a real clean job is with a water fed grinding wheel. I don’t suppose either of us has that option.

I have visited the Waterford Glass factory in Ireland. They use large water fed grinding wheels to create the beautiful cuts in the crystal.  

Barometers and some clocks (Golden Hour Clocks are very common) have a hole drilled in the center of the glass. Many times it is possible to drill a hole without breaking the glass. Here is the information I have picked up from experienced clock people and reading some articles on the subject:   

There are special drill bits for glass. It has a flat, barrel shaped, tip and is diamond incrusted. Some bits, especially larger ones, are hollow and only cut a ring rather than grinding out the entire hole. These are called core bits. Glass bits actually fracure tiny glass particles as it grinds its way through the glass. There are two key points to follow: 1. Don’t put too much pressure on the glass. Use your best judgement and don’t be in too much of a hurry. 2. Keep the glass cool. Put the glass inside a container of water. (note: I have heard that mineral spirits are a good option but I have not tried it) The object is to pull the heat away from the point you are working on and keep the glass temperature even across the glass.

Summary:

 Diamond hole saws.

Here are two sites I found that sells the drill bits and has excellent instructions:

http://www.drillglass.com

http://www.diamond-drill-bit-and-tool.com/Diamond-Drill/Default.htm?main_rt.htm