Grandfather Clock Moon Dial Ordering
Read this section before ordering a new moon dial for the grandfather clock. There are specific things to know so as not to purchase the wrong dial for your clock. Not all moon dials fit all clocks. In essence, each one is made for a specific clock movement. The reason being most moon dials have four feet, or posts, that stick out of the back of the dial. These feet have to lock into the movement. If the feet are in a different location, it will not lock into the movement. These grandfather clock moon dials are for post WW2 clocks only.
How to get the right moon dial
First, locate the movement number to get the correct moon dial. Without the movement number, finding a compatible dial will be impossible. So this is an important first step. The movement number can be found on the back plate of the movement itself. It will not be on any of the paperwork that came with the clock, or on the wood case. Movement numbers can only be found on the clockworks itself. Often customers will email pictures of stickers that are on the back of the clock. However this is not where the movement number will be. So please save yourself some time and make sure to get the numbers that are on the back plate of the brass movement. Match up the movement numbers to the ones in the list on the moon dial description.
What has to match
- The posts on the back of the dial need to lock into the movement. A long hand shaft on the movement will require longer posts. In other words, the posts on the back of the dial make it so the hand shaft will stick out far enough to put the clock hands on.
- If the movement is cable driven, the holes to wind the clock need to be in the right spot. This is important for when it comes time to wind the clock with the key or crank. When the alignment is correct, it will go onto the winding arbor of the movement. If the alignment is not correct, then winding will be difficult or even impossible.
- Some clocks have a second hand bit which also needs to have a perfect alignment. This goes onto the small post coming off of the escape wheel. Simply push on the second hand to install it.
On a chain driven unit, it is possible to get any moon dial and remove the feet off the clock dial. The dial would then have to attach to the wood case. Since a chain driven movement has no winding arbors, there are no holes to match up. There is also rarely a second hand bit. So any dial can be used with no winding holes and attach it to the wood case. However, one thing to mention is that the moon phase will most likely no longer spin.
Removing Mechanical Clock Hands
German Post WW2 wall, mantle and floor models
Removing mechanical clock hands for post WW2, mantle and floor clocks is quite simple. Turn the hand nut to the left while holding the minute hand with fingers.
Use some small needle nose pliers to loosen the nut first. Once the nut is loose, turn it with fingers until it comes off.
Then the minute hand will be able to wiggle straight off its square arbor and off of the clock. The hour hand is a friction fit, so just twist the hour hand back and forth and pull toward you until it comes off. If having a second hand bit, that is only a friction also, so just grab it with fingernails, twist pull off.
American Antique time and strike
These type of movements come in two styles. If there is a minute hand nut, the first style is the same as above.
Be very careful not to lose this hand nut. They are very hard to find and replace. The second style of mechanical clock hands will have a pin holding the minute hand on instead of a nut.
Save the washer and the tapered pin for ease of reinstalling the hands. If these items happen to get lost, Clockworks offers washers and taper pins for purchase, as well as replacement mechanical clock hands.
Grandfather Clock Moon Dial Installation
A Grandfather clock moon-dial installation explanation is in this section. Thus, this is written for a new movement installation in mind. However can use it for any post WW2 German mechanical unit with issues in relation to the front of the movement.
The moon gear
Install the moon gear onto the new movement prior to the clock moon-dial installation. It mounts with a set screw and sits on the same tube as the hour hand. Install this onto the new unit. Of course it has to be the same as it was on the old movement. Ideally, with the same approximate distance on the hand shaft. In essence, this will allow it to run the gears behind the clock moon-dial and therefore run the phase of the moon.
The selector switch
A selector switch is a steel arm that is about 1 to 2 inches in length with a set screw. In short, the purpose of the switch is to select the song or silence the clock. Install the selector switch on the arm which is on the right side of the movement. In other words, slide the switch over the larger arm and secure it with the set screw. It only has to be able to come through the slot at the 3 o'clock position for the user to move it up or down on the clock moon-dial.
Before install, check this
These modern clock movements from Germany use a rack and snail count system for the strike. Be sure the rack tail for the strike is on top of the snail instead of stuck behind it. See pictures that illustrate the correct and incorrect positions. Simply lift the rack back up into position with fingers. If this is not done the clock may not run, chime, or strike. It is important to get this done before completing the grandfather clock moon-dial installation.
Grandfather clock moon dial installation
The clock moon-dial has four posts on the back that lock into the front plate of the movement. Line up the clock hand shaft to the hole in the center of the dial. Then line up the posts with the holes in the movement. There are two ways to secure the four dial posts to the clock movement. One way has locking arms on the back of the front plate of the movement that slide over the end of the dial post to lock it tight. This is if both the clock moon-dial and the movement are made this way. The other way this is done is if there are holes in the ends of the dial post feet. These use a pin to secure it to the movement. A tapered pin will go through the hole in the post after it's on the front plate of the movement.
Moon Gear Mesh
Rack is Correct
Clock Moon Dial History
The phase of the moon is still popular on modern mechanical clock movements. It is interesting to know the clock moon dial history as to why and when the it became such a popular feature to add to grandfather clocks.
Why it began
In the late 1600's traveling took awhile and was also hazardous at night when it was dark. The people would depend on the light of the moon to see what they are doing when they were out. The phase of the moon function was an addition to the floor clocks for this purpose. People could make travel plans with the moon light helping them to see.
In the 1700's clocks began to have the hump on the top of the clock dial for the moon phase. The dial arch was able to accommodate the lunar display disk. The moon was painted on the disk and the disk would rotate once a month. It was a simple and practical addition to the clock.
Alternate Animations in the Clock moon dial History
Some clock dials with the arch were made with alternate animations besides the moon phase. Ships and jumping deer figures among other things would rock back and forth. These animations did not have any practical functionality as the phase of the moon did. It was a simple design in connection to the pendulum motion. With the swing of the pendulum, the animation would rock.
That is the history of the clock moon dial in its simplest form. It is always interesting to see how people live and rely so heavily on their clocks back then. In the days of outhouses and traveling with horse and buggy, a clock was an important appliance.
Hermle Clock Moon Gear
Moon gear for Hermle mechanical clock movements. This is the gear the spins the phase of the moon function on a lunar dial. It is the only interaction from the movement to the dial to make the dial lunar disk to spin. Installed on the same tube as the hour hand and secured with a set screw only.