Using an ESP32 WROOM 32D Microprocessor & Stepper Motor to Repair & NTP Time Synchronize a Worn Out Regula 25 Cuckoo Clock

About

I purchased an old Cuckoo Clock from Ebay and found three of the time train bushes & pivots were very worn.

The pivot hole should be perfectly round and there should be no side to side movement of the gear pivots in the pivot holes.

Below rocking each gear in turn showed a huge amount of wear on the pivot holes where over time the pivots had worn through the brass plates.

Rather than re-bush the movement/replace the gears I decided to remove the first worn gear to disable the escapement and drive the clock from an NTP syncronized stepper motor.

Disabling the escapement from the clock means the clock/hands will free run when the chain gear for time is rotated.

By controlling the stepper motor attached to this gear allows precise control of time keeping via a NTP server.

The cuckoo and gong chime were left in place powered by the original weight and chain drive.

To keep the clock looking as original as possible the time movement weight and chain was fixed in place under the clock and a battery powered pendulum movement was added to the rear of the case.

Controls and LED indicator panels were hidden behind the bird and leaf ornament on top of the clock. A hinge was added to allow acces as required.

I used a 3D Printer to print the extra parts for this clock.

Functions

NTP precision as time is fetched from an NTP server to synchronise the cuckoo clock time.

The time train is driven by a microproccesor controlled stepper motor attached to the clock time train.

The clock hands move once every minute.

Chime is weight and chain driven but is synchronized exactly to the hour and half hour.

Summer and Wintertime is easily set from the control panel by a single button push.

The time part of the clock never needs winding but the chime part will need winding.

Clock controls and LED panels are hidden behind the hinged top decoration.

Clock Control Panel Clock LED Indicator Panel

Video showing clock moving to 2 o'clock and cuckoo/chime sounding out the hours.

Donor Clock

The clock was purchased from Ebay as spares or repair for £18.00. Working versions go for around £200 so you don't want to do this modification to a working clock.

The modifications can be revearsed if you want to rebush the clock in the future and revert to the original.

Regula 25 movement front

Regula 25 movement rear

Problems with the donor clock

Although the clock was complete the case was very dirty and there was a badly repaired joint on the right hand leaf on the top of the clock.

The digits and hands should be white as can be seen by the clean bit of the minute hand where the clock has been adjusted over the years.

The clock has a thick greasy yellow covering of dirt possibly from tobacco smoke over the 70 odd year life of the clock.

I gave the whole clock a good scrub down with soapy water and wire wool.

I pulled the repair on the leaf apart scaped of the old glue and re-glued with super glue.

The case stain was very patchy and worn in places so I touched it up with water based stain.

The best match I found was called English leather and a 50ml sample bottle contained more than enough.

Cleaned and repaired bird/leaf ornamant.

Original clock on the left with the yellow tar/dirt removed and wood repaired.

Dismantling the old Cuckoo Clock

Cuckoo Clock designs vary but see this video for a guide.

Remove the chain, weights, movement, cuckoo and bellows.

Remove the carved wooden ornaments from the clock.

The top ornament is held on by screw in a bracket.

The front ornamant is nailed down fron the roof and also from the front.

Carefully prise these off.

Remove the hands and dial. The dial is held in place by 3 pins.

Remove the 2 metal brackets for the top ornamant.

Remove the fixed rear panel. This maybe pinned/glued so use a craft knife to cut away any glue between the panel and frame.

The panel needs to be removed to allow acces to fit the veroboard and wiring.

Clean and repair the case/ornamants as required.

Parts not used and removed from the clock

1st escapement gear.

With this worn gear removed the clock is free to rotate when power is applied to the chain.

Parts Diagram

Cuckoo Clock Movement Regula 25 Parts List

Num	Part		Num	Part
1	Base Plate		22	Spring for Locking Lever
2	Locking Lever		23	Bird Post
3	Retaining Washer, 1.5mm		24	Bird Post Spring
4	Tripping Gear		25	Minute Wheel
5	Gathering Pallet		26	Hand Gear
6	Munute Gear Shaft		27	Washer for Minute Wheel
7	Chain Gear,Time		28	Rack
8	Middle Gear		29	Star Wheel
9	Escape Wheel		30	Lift-wire Shaft 1
10	Chain Gear, Strike		31	Lift-wire Shaft 2
11	Gathering Pallet Gear		32	Hammer, Complete
12	Strike Release Lever		33	Shut-Off Lever
13	Fan Wheel		34	Bushing
14	Fan		35	Spacer, 4mm dia,5 x 0.1
15	Cover Plate		36	Hand-Nut Bushing
16	M3 Hex Nut		37	Hand-Nut Bushing
17	Verge		38	Washer, 2.6mm dia, 6.6 x 0.8
18	Alert lever		39	Hand Nut
19	Compression Spring		40	Chain, 1800mm long
20	Locking Lever		41	Chain Ring
21	Retaining Washer, 1.9mm		42	Chain hook

Escapement anchor not required but can be left in place.

Pendulum leader.

Not required as a replacment pendulum dive unit is added to the rear of the clock.

Adding the stepper motor to the movement

I removed  the last gear of the escpment train (with the worn out pivot) so the movement could turn freely.

To remove the gear I just losened the movement nuts A a little bit and then losened nuts B enough so the gear could slip out.

If you are carefull no other gears will fall out. While the movement was loose I also removed part 17 "verge escapement" (pic5). This is optional and just clears some space.

Once these parts are removed the nuts can be tightened up.

To replace the removed gear I found a Meccano Spur Gear 57 Tooth Part 27a (from Ebay) fitted very well.

The gear ratio is not too important as the gearing can be adjusted in software.

The gear is fitted to the drive shaft of a 28BYJ-48 stepper motor.

A small 3D printed bracket fixed under a movement nut holds it in place.

The stepper motor is hot melt glued to the bracket and is able to pivot in place around the fixing bracket.

Assembling the clock

The movement with stepper motor added can now be fixed back in the clock case.

The Veroboard is fitted under the roof held in place by the 3D printed Veroboard clamp and the 3D printed rear cover.

Fit the bellows & cuckoo back in the case attaching the operating wires.

The pendulum hanger can be left out as it's not required.

Insert the 3D printed clock rear in place. Bolt through the roof in 2 places with M2 nuts & bolts.

Push M2 bolts through the side of the clock and the rear cover. Nuts are not required over these bolts.

The 3D printed clock hanger is bolted to the rear cover.

Take the wiring out through the square hole in the rear cover and through the hanging bracket.

Make sure any moving parts of the clock are clear of any wires.

Fix the 2 off 3D printed side brackets to the case cover.

Then fix the Quartz Pendulum Drive Unit Module to the cover with 4 off M2 screws.

The rear cover fits in the case as before locked in place with the catch removed from the old rear.

Screw the Chain clamp in place under the clock.

The slot in the clamp is oversized to prevent damage to the chain so add some soft foam to make sure the chain is secured.

On the front of the clock add the carved ornaments removed at the start.

I fix with M2 screws instead on panel pins.

The top ornament is fixed to the 3D printed hinge comprising of 2 off roofmountbracket and 1 off roofMount.

Dial and Sensor Unit

The clock uses a sensor in the dial surround to tell when the minute hand is at the 12 o'clock position.

A small Neodymium magnet is glued to the tip if the minute hand to operate a hall effect sensor as it passes.

A 3D printed Sensor ring with cutouts for the leaves surrounds the dial and houses the Hall effect sensor.

It is fixed with wood screws to the case over the dial.

The small Neodymium magnet is glued to the underside of the minute hand on a copper wire.

Completed Clock with weights and chains in place.

Note the time trian weight and chains are fixed in place under the clock using a 3D printed chain clamp.

Clock Wiring

The wiring from the stepper motor is plugged into the stepper motor board mounted on the Veroboard.

The wiring for the control panel and LED display panel mounted on the roof are taken over the ridge of the roof and terminated on a socket on a small Veroboard at the back of the clock.

Cables from the Veroboard are plugged into this socket.

The wiring is covered by 3D printed covers on the ridge and rear of the clock.

Below-Cables terminated on the small Veroboard at the rear of the ridge of the roof.

The micro USB programming cable can also be seen comming out the back of the clock plugged into the ESP32.

3D printed ridge cover and rear roof panels cover the wiring on the roof.

Top view showing the wiring covers and flip up ornament hinge.

Wiring Schematic

The main Veroboard is mounted under the roof.

The connection Veroboard is located at the rear of the ridge cover.

The hall effect sensor is wired through the rear of the case above the dial.

Schematic

Veroboards

Main board with modules in place.

Main board with modules removed.

Main board rear.

Control Panel Veroboard

Rear

LED Veroboard

3D Printed Parts

bracket 1 off

Holds the stepper motor in place. Fixed to a clock movement fixing bolt.

chainclamp 1 off

Holds the old time chain in place under the clock.

clockrear 1 off

Replaces the old clock back.

controlPanel 1 off

Panel to hold the control switches.

hallSensorHolder 1 off

Veroboard mount for the hall sensor module.

HangingBracket  1 off

Fixed to the rear panel and provides a wall mount for the clock.

LEDBracketCover 1 off

Covers the LED bracket wiring.

LEDHolder 1 off

Bracket to mount the LEDs.

LEDholderA 6 off

Holds the 4 off 3mm leds in place

Ridge 1 off

Covrs the wires to the control switched and LED on the ridge.

RoofCover 1 off

Glued to the roof ornaments to cover the gap to the roof.

roofcoverrear 2 off L and R (reverse in CURA)

Covers the rear of the roof and fixed to the roof with M2 screws.

roofmount 1 off

Fixes to the roof and is the pivot point for the 2 off roofmountbracket

roofmountbracket 2 off

Fixes to the roofmount with M3 nut and bolt and the roof ornamant with M2 screws.

sensorringcutout 1 off

The hall effect sensor fits in the top of the ring which is fixed to the case.

side 2 off left and right (revearsed in CURA)

Fixes to the rear of the case to alow space for the minute pendulum.

stepperdriveholder 1 off

Mounts the stepper module board on the Veroboard.

switchcover 1 off

Covers the control panel wiring.

switchcover 1 off

Fits between the controlpanel cover and the Control panel Veroboard to space out the switches.

Veroclamp 1 off

Fixes the base of the main Veroboard in place with an M2 screw.

Clock Operation

RST- resets the ESP32 microprocessor causing the clock to restart

Win - Sets the clock to wintertime. Note cuckoo clocks can't go backwards so the clock will stop for 1 hour indicated by the "WIFI Get" and "WIFI Fail"

LEDs alternating on/off.

Wintertime setting in progress indicator

Fast - Steps the clock forward quickly

Slow - Steps the clock forward slowly

End - steps the clock on until the minute hand reaches o'clock

Start - steps the clock to the current minute (presumes clock is at End Stop position.

Starting the clock

On power up the clock will log into your router and then get the time from the NTP server set in the code.

Indicators when logging into the router/NTP time server.

Once time has been fetched the Gn LED lights and the clock will start stepping until the end stop is reached and will then stop.

End stop reached Wh end stop LED lights.

To set the hours first lock the cuckoo door to stop the chime as the hour is set.

To lock the door just turn the catch above the door.

To set the hours press and hold the "Fast" button to step the clock forwards quickly.

As the correct hour is reached stop the clock at 12. Use the "Slow" button to stop the minute hand exactly as the "End Stop" LED lights.

Unlock the cuckoo door.

Pressing "Start" will then set the correct minutes on the clock.

When "Start" is pressed the Green LED goes out followed by the "End Stop" LED when the sensor turns off as the hand moves away.

Silence the Cuckoo/Chime at Night

To silence the clock at night just lock the cuckoo door by turning the door latch down.

Code/3D Printed Parts

3D Printed parts in zip file FreeCAD and CURA files included.

Code

Title image by ddraw on Freepik