There comes a time when a clockwork clock can't be made to run properly any more. If you want to fit a quartz module, they are cheap and reliable, but you might need to drill a big hole in the clock face, and you probably won't be able to use the slim beautiful original hands that match the clock, because the shafts of a quartz module are usually 5.0mm or 5.5mm diameter. On my lovely mantel clock, the hands themselves are narrower than that.
The solution is given in this Instructable.
Step 1: Keep the Original Motion Work!
In a lot of traditional clocks, the clockwork mechanism (that is worn out) drives the main wheel which turns once an hour (for the minute hand). This is on a shaft that projects right out of the back of the clock and ends in a small knob used to adjust the hands. So we can use the quartz movement to drive this single shaft. But what about the hour hand? That one goes round once every 12 hours. In your quartz movement it is turned by the outer shaft, probably a clear plastic tube. How are we going to connect that one? You can't, but you don't need to. On the front plate of the original clock, behind the face, is the motion work. This is a couple of gear wheels that are moved by the main wheel (one turn per hour) and reduce that motion to one turn in 12 hours to drive the hour hand. All that can stay in place on the front of the original mechanism, while the minute hand shaft on the quartz module drives the minute hand shaft from the back of the clock.
Before going any further, decide whether you want to destroy the mechanism of your lovely clock. If it just needs cleaning and oiling, read no further!
Step 2: You Will Need...
A quartz clock module. You can buy these cheaply online, or you can take one out of a horrible old kitchen or bedroom clock someone once gave you. They look pretty much all the same, but there are different qualities available. If you are buying one, it might be worthwhile going for the high-torque version. Some of them come with a screw-on boss that holds the hands in place. I used this to connect to the clock. If you don't get that, you can make a connector from some tubing.
Step 3: Remove the Movement From Its Housing
Of course, there are lots of different arrangements. You need access to the main part of the mechanism, and you might be able to leave the face and hands in position. With my clock, I needed to:
Remove the winding key (by turning it the wrong way),
Pull off the knob that adjusts the hands (don't lose it)
Take off four nuts that hold the cover in place, and remove the back cover,
Slide the mechanism and face out of the front of the wooden chassis.
Loosen some screws to remove the inner cover.
Take some photos as you go, to help you put yours back together later!
Step 4: Bind Up the Main Spring
Your clock contains a source of power that can actually be dangerous - the spring. This needs to be made safe before you remove it. You can be sure that even if the clock doesn't work, the spring still has a kick in it.
If the spring is the open sort, so you can see the blue-black spiral, it needs to be tied up. one way to do this is to use cable ties. Put a tie through the middle of the spiral and fasten it to itself at the outside, to hold the spiral together. See if you can get about three or four of these in place so that spring is really bound up.
In many clocks, like mine, you will find the spring is inside a barrel and cannot get out (unless you unfasten it!).
Next, removing the escapement will allow the clock to run with no resistance until the spring has gone as far as it can within its bonds.
Step 5: De-powering the Spring
The best way to run the spring down is to remove the escapement. On this clock, it was easy to remove the escapement assembly comprising balance wheel and escapement (as shown). With this taken away, you will travel through time, as the remaining energy in the spring drives the hands round and round. If you don't have a simple unit to detach, just damage and remove the lever that connects the balance wheel to the escape wheel (the thing that ticks). Or you might be able to unscrew the bearing at the end of the balance wheel and take that out. Then remove the escapement so that the escapement wheel is free to turn. And it will!
Once everything stops moving, the spring should be safely bound up, but be careful with it.
Step 6: Remove Going Train
The going train is the series of gear wheels that move the minute hand. Often you will have the main wheel in the middle, driven by the mainspring, and held back by the escapement and balance wheel or pendulum. We need the main wheel to move freely . You may be able to leave some of the wheels in place but in this clock I removed all four including the spring barrel because all the shafts (arbours) run in holes in the front and back plates. So I loosened the screws holding the back plate to the spacers, and moved it enough to take out the wheels with tweezers and pliers. Then I tightened up the screws and kept the back plate in its place. The main wheel was on a long shaft that was easy to leave in place - and you need it!
Now if you turn the shaft at the back, it should spin freely. If you still have the hands in place you should be able to whizz them around. If there is any stiffness you need to sort it out, because the quartz movement has very little power to overcome any resistance.
Step 7: Make Connector
I fixed the threaded cap from the quartz module to the adjustment knob to make a connector.
First, I drilled a hole in the centre of the cap, using a fine drill the same size as the minute shaft. (To get the hole in the exact centre do this I made a makeshift lathe by strapping a power drill to the bench and putting the cap in the chuck. Then I used a hand drill resting on a stack of wood offcuts to hold the drill at the right height.)
Next I tinned the face of the cap with solder and threaded it on a small screwdriver held in a vice. I tinned the end of the time adjustment knob and slid it on, then I was able to solder them together absolutely concentric and true. If you don't have the soldering skill, you can use your favourite adhesive.
The knob will be a push fit on the minute shaft as it was in the original clock, and the minute shaft of the quartz module now screws into the cap and turns it.
For a different clock or module you may need to design your own adapter / connector. Brass tube can be bought in different sizes and can be soldered together. Or a plastic tube may be made to fit. It is important to get the connection straight and concentric, otherwise the assembled unit won't turn easily.
Step 8: Assemble to Clock
Next I screwed the clock shaft into the connector, and determined where the module should be fixed. I was able to secure it with a couple of pieces of wood glued to the back of the clock. Then I put in the battery and set the hands using the wheel on the module and everything was great!
Step 9: Problems Encountered
I never realised the movement of the quartz module would be sudden and jerky enough to loosen the screw-on connector. After a few days, it unscrewed and the hands stopped moving. The solution was to put some glue on the threads to lock it together. Since then it has been working nicely!
I hope this gives you a new way to save an old clock. If anyone uses this method, please post some details!