Murday/Reason

In around 1908 John Thomas Murday invented an electromagnetically impulsed clock with a large horizontal balance wheel which used a Hipp toggle to synchronise impulses to a solenoid.

The clock was put into manufacture by the Reason Manufacturing Company of Brighton, England. It was not terribly successful and only a few hundred were built.

The clocks that have survived are sought after and fetch values in the order of several thousand pounds.

It is a very attractive clock mainly because it has a a number of dynamic aspects such as the large oscillating balance wheel, solenoid impulsing and the Hipp toggle.

Commercially available designs are available, notably by John Wilding, for those that have the skills to make their own.

My interest is in making clocks with as large a wood content as is practically possible, but for this clock I had to make some compromises. The original has a period of oscillation of the balance of  four seconds. I couldn't make a wooden balance wheel that had enough mass to give a  low enough frequency with the 'hairsprings' I had available. Thus a friend forged a strip of steel into a ring and with the addition of brass weights I reached a period of about 3 seconds. Short of going out and buying a new spring I decided to be satisfied with that.

The suspension system for the 500 grammes or so of balance wheel is a pointed steel balance shaft running on a metal platen to act as a thrust bearing. The upper end of the shaft is supported in a plain brass bush. The spring came from the mainspring of a mantel clock. The original uses a sapphire thrust jewel and this will be investigated if not too expensive.
Update: Ultimately the steel platen proved unsatisfactory by wearing too much. A harder support made from a strip of spring steel, softened, worked with a small hemispherical depression and re-hardened proved much more resistant. In the long run this was replaced by a degreased high quality ball bearing. The balance wheel now runs between 6 and 8 oscillations between impulses, seemingly at random.

The two solenoid coils are wound on soft iron cores with wire of unknown gauge such that they have a resistance of 50 ohms each. This takes seventy grammes of wire. The coils are wired in series and arranged  next to each other so that a pivoted keeper is pulled onto the poles when the coils are energised and impulses the balance in doing so. I use 12v pulses whereas the original used 3v dry cells but since I was starting from a position of not knowing the original's number of turns and gauge of wire I am comfortable with that. The pivoted keeper is returned to its idle position by the returning balance wheel and held securely by a light magnetic force


The Hipp toggle is of standard design working with a vane mounted on the balance wheel. To avoid largish currents across the contacts I have used a timer relay to give consistent pulses to the coils.

I was unable to implement a satisfactory regulation system with a curb on the 'hairspring'. Instead I trimmed the mass of the hexagonal balance weights until the clock was running slightly fast. I then implemented an 8gramme sliding weight on one of the balance wheel spokes. The further away from the centre this weight was set slowed the oscillation of the wheel and I was able to bring the clock into regulation. This was a later modification and is not shown on the video.




All the features are best seen by watching the video below.




The casework consists of an octagonal veneered base in which the timer relay is located. The Transparent octagon is 1.7mm styrene sheet panels glued together at top and bottom by black angle pieces of the correct angle and 3d printed, Perspex or glass would be a better option but the styrene was to hand.

The dial consists of laser cut segments of a translucent Perspex set in a laser cut wood frame.

There is a 3 LED to give some subtle lighting mounted on the baseboard.

The elephant is optional.

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