Written by GRAHAM MULLIGAN - 2010

After reading the article Dual Oscillators in the Horological Journal, I thought about the idea of making a truly unique clock.

My experience in horology started approximately twenty three years ago when I started repairing clocks as a hobby, and after finding myself unemployed, took the step to clock repairing as a full time vocation. During those twenty three years, I have gradually built up a repair business and eventually put together an antique clock repair and sales shop with hundreds of clocks and watches in the CBD of Launceston, Tasmania.

Please forgive me in my lack of technical input in this article as I build clocks from the heart, not the head. Back to the clock in question; after reading the two-part article on dual oscillators, I was fascinated by the whole concept of it. It had been two years since I had built my last clock so it was about time that I started on another project. I searched through the cupboards of my workplace for a starting point and found a 1850s fusee movement with a long-drop pendulum. It would suit my idea perfectly, all I needed was the wheel work. I have not advanced yet to cutting my own wheels, although I am more than capable, it is more time saving using what I have accumulated over the years. Ideas in my head for different and more interesting clocks to build might see me cutting my own wheel work in the future. The first step creating a timepiece for me is to sit down with pen and paper and draw what is in my head. When I am happy with the design, I then draw it to scale, purchase all the brass that I need, then make a start. Originally I was going to put the clock on two old French marble clock bases, but then decided against it because it may look like I had made it out of an old French clock. I wanted more of myself in the clock and less of a replica of someone else’s design. I then visited the local stonemasons, where I purchased a solid polished block of black Tasmanian granite. I drilled four holes into it for my columns with an altered masonry drill bit and plenty of water. Two hours later the holes were finished. The first part of building the actual clock was to build the two identical pendulums and a suspension block to hold them. I wanted to do the pendulum first to experiment on how they worked when one was impulsed. When I had all of that built, I fixed it in the bench vice, and pushing it gently with my finger it seemed to do what I wanted it to do. So I packed it away and went on to build the clock movement. In the past I have drawn the plate design on paper then glued it onto the brass sheet, gang drilled around the plates and cut it out with the fret saw. This time I did things differently, taking the design and brass sheets to a local engineering firm where they loaded my design into the computer and then laser-cut the two clock parts out. At a cost of A$120.00 it saved me a lot of time and hard work. I have since been told that they cannot do it anymore, so it might be back to the dark ages with my next clock? This part of the clock was fairly straightforward and simple, to lay out the gear work in the new plate design. All went well, I had the new movement up and running in no time. Now comes the exciting part of getting it running by fitting the suspension block and the two pendulums. I had not made the base at this stage so I clamped the movement to the bench and hung the pendulums over the edge of the bench. I gave each pendulum a gentle push in opposite directions and away it went, for about thirty seconds, and then came to a slow stop. I checked the beat; that seemed fine. I removed the back pendulum and set it going. Leaving it for a few hours, it had a good strong tick and everything appeared to be working. So I added the second pendulum and set it going again. Sure enough about thirty seconds later it stopped. The suspension block that I had made up was two halves of brass at the top bolted together and two halves at the bottom bolted together and joined by a solid strip of suspension spring. The pendulums hooked onto the same block at the bottom. What I was trying to achieve was for the movement to impulse one pendulum and in turn, then impulse the other through vibrations. Alas, it would not run, so I decided to try a swivel link in my pendulum hooks that was achieved by using a hardened pin and balance wheel cones. That kept it running for a little longer, but it still stopped. Next step would be the actual suspension spring. I punched a series of holes along it to give it a little more flex, which worked for a while but then stopped. I then started to thin the spring in the middle. All of these variations seemed to help but still no luck. I tried cutting the whole centre out of the spring and leaving two strips at either end like a traditional suspension spring, it seemed to improve things but again it stopped. I experimented with different thicknesses, lengths and styles over the next month to no avail. It was becoming frustrating . . . It almost came to the point of deciding to cut the second pendulum off and just have a simple fusee skeleton clock. I then decided to try one more combination to cut the bottom block of the suspension spring into two pieces and link them with another piece of spring steel, so that the suspension spring had freedom to move on two different axis. I set it all up and put the two pendulums on, set them in motion, and to my amazement they kept going. The clock ran for the rest of the week. I had solved my problem and could now make the clock that I had wanted. There is not a lot written about twin pendulum clock making, not that I could find, so it was all coming from trial and error. Please note that I was not building the clock with the view that it was going to be superior in timekeeping or efficiency than any other clock. I was looking for the novelty of twin pendulums off a single impulse unlike all the twin pendulum clocks built in the past, which have used either two movements side by side to impulse each pendulum, or one movement with twin escape wheels impulsing each pendulum. Now that I had the clock running, I had to lift the movement up high enough for the pendulums to swing. This was achieved with the use of four columns from an old French marble clock case that was broken, and four solid brass blocks to make up the difference. Now it was starting to take shape and look like a clock. Next step, a piece of brass screwed onto the faceplate of the old trusty Myford ML7 and then indexed to mark out the dial. I engraved the chapter ring, the minute markers and all the tops and bottoms of the roman numerals in the lathe. The rest was done with the steel ruler and scriber. It was then finished off with a dental burr, black waxed, and silvered. With the clock just about finished it was now down to the case. I was a bit unsure with what I wanted. I thought about a wood and glass case, again I wanted to make it from scratch also. After much thought, I decided to make it out of brass and I wanted to incorporate the base of the clock as part of the clock, so that meant discarding the granite block and getting a bigger one that had a step in it so that the case could sit on it. So here we go again, another four holes into the solid granite base thinking about all those wasted hours on the last base. The top of the case was solid brass with square brass sides, solid brass bottom with the centre milled out to go over the granite base and sit on the shoulder. 2mm slots milled into the four corner pieces for the glass. With all that finished, it was starting to look good but then I discovered a problem because of the height of the clock. When it was on a mantel, it made it just about impossible to lift the glass top up to wind it up. So to fix that problem I drilled a hole in the glass, made up a brass grommet with a swivel cover, then made two more grommets on either side of the case so I could push each pendulum in opposite directions to start the clock. With all that finished, then came the part I regard as the worst job: polishing it all. I was not too fussy with the polishing part not because of laziness, but because I wanted the clock to have an older look, not like it had just been freshly made. So I purposely left a few little dings and scratches in all the brass work. I was very happy with the finished product. It has been running now for over a year and I have been regulating it. I must also add, that it is not an easy clock to regulate.

Graham Mulligan, Horologist