Printed Pilot [time setting] dial and motionwork for the Gents' WT40A.

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 Following the images of the motionwork, in my last post, my contact has added a pilot dial.  The compact mechanism is driven by the WT exactly like the hands on a turret clock dial. The minute hand is directly driven by the bevel wheel cluster at 1 rph. The hour hand reduced to 1 revolution per 12 hour day. By the two pairs of spur gears with a ratio of 12.1. A typical, clock's motionwork. All thanks to precision, printed parts in bronze plastic.

The white dial even has the Gents' name for a further touch of authenticity. The raised numerals are a very nice touch. Reminiscent of Gent's very own exterior dials produced in massive cast iron. Though usually on a much larger scale than here. 

These dials were typically driven by a slave, impulse dial mechanism and intended for exposed positions. Or even to be sited where there was a risk of explosion from a spark. Such as an explosives factory. Or where the atmosphere has flammable gas or vapours present.

 This dial is small enough not to hide the features of the WT and certainly looks the part. Providing a time service as accurate as the master clock which controls the WT via the Gents' Waiting Train mechanism. Where, twice a minute, the drive to the clock hands is paused for about 2 seconds. A D-shaped pin, on the escape wheel, has lifted and locked the drive pawl, masking detent.
 
 Then the next, short, electrical impulse from the master clock reaches the WT's small, relay electromagnet at 30 second intervals. Allowing the drive pawl to drop back into the teeth of the WT's escape wheel as the masking detent drops. The hands move on without the pause being perceptible to the observer.

 I think you will agree that this pilot dial makes a compact, interesting and attractive feature. Moreover it allows more accurate setting of the WT to time. For example, when the clocks go back and forwards for summer and winter time. Or after a stop for maintenance or lubrication. 

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Printed clock hands and motionwork for WT C40A.

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My contact with the C40A has kindly forwarded some images of his newly printed clock parts. 

He wanted to show the time on his WT. While the time setting dial can show the time [against suitable, fixed pointer] it does not have an hour hand. Much like most other turret clocks with time setting dials. So he printed clock hands, a bracket and the gearing [12:1] motionwork] to make the time more accessible.

The WT has an output of 1 revolution per hour. Or minute hand time. This has to be slowed by 12 times to drive an hour hand. One revolution per 12 hours. The compact, 3x & 4x spur gear,  reduction is known as motionwork. i.e. Producing the motion of the hour hand. The reduced speed is applied to an hour pipe. With the original minute hand on a shaft running inside the pipe. This is common to almost all of the mechanical clocks ever made. Including electrically driven clocks and slave dials.

My contact has cleverly printed a supporting bracket. This uses the original holes in the WT mainframe for fixing screws. 

One should never arbitrarily drill new holes in items of historical or antique value. Originality is highly admired and can make or ruin the resale value of items like clocks.  

The images show the details of the clever conversion to hour and minute hands. Provided there is low friction, the motionwork should not affect the working of the WT. The time cannot become wrong because of the enormous reserve of power available. More frequent impulsing of the pendulum is the usual sign of increased friction. This should be attended to immediately in order to avoid costly damage to irreplaceable parts.

Even the Gents' "Pulsynetic" brand name has been printed on the bracket. I doubt that anyone will be fooled into thinking this is an original WT part. Simply due to the materials used in the 3D printing.  Which is obviously intended as a fun exercise. Most owners of a WT and master clock would use the pilot dial in the master clock for timekeeping. Or place a slave dial nearby.

I use a Gents' slave dial on the wall above my WT. With a large, turret slave movement on the external dial. This avoids any risk to the WT. Which runs continuously but unloaded.

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18.11.2021 A WT C40A using 3D printing for missing parts.

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I have been contacted by a WT owner. Whom has cleverly 3D printed some missing parts.  

Of particular interest is his printing of a bevel gear, crown wheel. Even down to his use of the correct bronze colour. The bevel gears [or bevel wheels] sometimes seem to go missing when a WT is removed from an installation. Spares are rarer than unicorns these days.

 I think I also notice a couple of printed, universal-expansion joints for the lead-off work. Making the drive to large dials possible. 

 My contact has kindly forwarded some fine images of his WT. For which I am very grateful. I have reduced the size of the original images to cater for those on a slow internet connection. Any reduction in image quality is entirely my fault.

The overall impression of this WT is that it could have just left the factory. Despite being at least 70 years old. This WT has been beautifully restored and finished. Making for a superb, working, display item. The timber stand is very pleasing and a close match to originals I have seen online. The diagonal struts are useful in resisting the power impulse and should extend the period between mechanical impulses to drive the pendulum.

Certain details point to a later WT movement. It has the pressed steel, contact, steady bars. Rather than the earlier cast brass. Small parts are plated for protection. Rather than the earlier, deep-gold, lacquered brass. The sloping mainframe bar, over the power [pendulum drive] electromagnets, is indicative of a slightly later model of WT C40A. Probably 1940s-50s? 

Interestingly, the coils are silk wrapped wire. Which is the earliest winding arrangement of the huge coils by the Gents factory. Later, the coils were wrapped individually in a protective bandage. Intermediate coils were wax dipped to prevent moisture ingress.

This image shows the overall view from the rear of the WT movement. I used the terms "front" and "rear" because the time setting crank and dial were at the front. Not all WT movements were placed for easy access from both sides.

This image shows the similarity of the 3D printed, bevel, crown wheel to an original. One has to stare hard at it to see any difference. A truly remarkable feat using modern technology. Not to mention considerable skill and patience.

The bevel gear cluster is driven by the worm wheel shaft via the first, vertical, bevel wheel. The larger, horizontal, crown wheel drives all the other wheels. Allowing a drive for the hands of up to three dials. A fourth dial would require a coupling on the far end of the worm shaft.

Many towers would have a dial on each face. Each placing greater demands on the WT depending on wind speed and direction. Plus any ice forming on the very exposed, metal hands. The clock hands would normally be balanced just behind the dial. Using counterweights, on extended arms, jutting from the shafts. Ice would add considerably more weight to the hands. Causing the clock to work harder "uphill" as the hand rise and running ahead on the descent.

Another view of the bevel wheel cluster. A very satisfying appearance. I have zero knowledge about the strength of 3D printing materials. The WT can produce enormous torque when it is demanded. Which is why it is built to resist all the likely forces applied to the large, exposed, clock hands. Often on multiple dials over a long, working life and usually in less than ideal conditions.  

Many clock rooms, towers and roofs would suffer from wind blown dust, rain, snow and debris. Particularly if bells were employed behind open louvers. Birds would often carry twigs into buildings for nesting material. Proximity to the sea would carry corrosive salts in the air.

Many WTs would be protected by a simple wooden box placed over the movement. This protection would often be complicated by the lead-off rods. It relied heavily on the clock minder replacing the box after examining the WT movement. 

  

End view of the WT with the original "Pulsynetic" label on the sloping section of the mainframe.

The compact form of the WT, compared to weight driven clocks, is readily apparent. Not only that, but no weight shafts would be needed. Nor safe and easy access required for a clock winder and minder.

This allowed WTs to be placed in very unlikely positions compared with weight driven clocks. High up on narrow war memorials. In niches on factory chimneys. Inside illuminated dials on train stations. They were also employed to slowly drive display mechanisms, museum and exhibition items.

The worm shaft [arbor] rotated at 1 revolution per hour. Clock dials have a 12:1 "motion work" to drive the hour hands. A straight-through shaft would drive the minute hand inside the "hour pipe." The hour hand would be fixed onto the hour pipe.

The view from the opposite end. Where the terminal block is fixed. This has separate screw terminals for power and for timing pulses. The timing pulses arrive at 30 second intervals from a master clock in a series circuit including dials. The short pulse in the series circuit releases the temporarily locked "waiting train" mechanism. 

A small electromagnet is energized by the electrical pulse. Which releases an arm which was holding back the WT's drive to the clock hand[s]. The pause is usually so short [2 seconds] that the effect on the clock dial is never noticed. The drive to the clock hands is otherwise continuous. 

The huge, drive electromagnets require 20Volts DC and at least 0.5A. The pendulum uses a Hipp Toggle and V-block to call on a drive impulse if the swing [arc] drops below certain level. The impulse can be repeated as often as necessary to maintain the swing. Providing up to 30 times the power of the occasional impulse!

 Note the small hand crank jutting from the front of the WT movement.
This was used to set the WT's dial[s] to time.

Here the view is from the front of the movement showing the bevel wheel cluster seen through an aperture in the WT frame.

The Hipp toggle and damper lies just below. The damper prevents the Hipp toggle from catching in the V-block on the return journey of the pendulum. A stub of rubber hose on the tip of the arm silences any rattle. 

The original, time setting dial is present on the face of a bevel wheel. The hand crank would be turned on the WT worm shaft [arbor] to move the hands on the dials forwards. A pointer of bent brass sheet is usually present to indicate the time. 

The time setting dial having quarter hour markers. A valuable asset before the mobile phone could be used to tell the clock adjuster the time showing on the external dial[s.] A regular difficulty arising when the annual Spring and Autumn time adjustments take place for Summer and Winter Time. Also known as "Daylight Saving Time."    

A close-up of the lead off work on the end of the worm wheel shaft. [arbor in horological terms] This link would often provide the drive to a single dial. Or a further dials if a bevel gear cluster was present.  The printed expansion link is in the foreground. Yet to be trimmed to two bars to fit into the forked element just beyond.

This clever arrangement has been used for centuries in turret clock, lead-off work. The drive rods to the hands of distant dials, would expand and contract in roof spaces and towers with changing temperature. Soaring in summer and freezing in winter. The change in rod length could be accommodated by the slots ion the drive links.

Old buildings would settle and move over time. Requiring a degree of flexibility in the lead-off work. These reliable, low friction, bar and fork links provided the vital freedom in the [often] very long drive rods. The earlier links would probably be hand forged by a smith in red hot iron. 

The further advantage of a fork and bar, drive link was the inability of the drive rods to turn backwards. So that the time would not be lost due to any imbalance in the system. [Ice or wind on the hands] Nor vary much between widely separated dials on different parts of a building. Few architects would have the necessary funds to provide a separate WT for each dial on a building. Multiple WTs were usually reserved for the very largest dials in history. On prestige building projects at the beginning of the 20th Century. The Liver Building in Liverpool being an excellent example.

One weakness in the drive rod [lead off] system was corrosion in the plain bearings required to keep the rods on line. Weight driven, turret clocks usually had a much smaller safety margin against friction or wind pressure on the hands. The clock would stop. While the WT was uniquely powerful thanks to the automatically demanded multiples of drive impulses to the pendulum. All thanks to the genius of the Hipp Toggle system.

This might cause problems. If the power demand was simply to overcome friction in the lead-off work. Possibly even causing damage. Clambering about in a vast, draughty and unlit roof or tower. To check for bearing tightness in the lead-off work, can't have been an easy task. The WT would carry on regardless until something finally broke. This might explain the loss of bevel wheels. If the [bevel gear] teeth were the weakest point in the whole system.

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