Escapement

I removed the DUFA's hands and dial. Which leaves the front plate showing the motion works (the parts that turn the hands). You can see that this movement also uses a  rack & snail  for its striking. When the rack is activated it starts things turning in the back of the clock. Here is a rear view of the movement showing the hammers on the strike. They are attached to arbors that turn as part of the strike. When the clock strikes those arbors turn, lifting the hammers, and then they release the lift such that the hammers drop and strike the gong rods in the case. Here you can see how the hammers are all connected to a cylinder that is screwed onto an arbor. The left set has been removed from their arbor in the photo below. So... How does that lifting of the hammers actually happen? The rack and snail determines how many times the clock should strike.  When the rack and snail are activated the strike train turns the pin wheel (seen below) counterclockwise. As it the pin...

The DUFA is the first tall case / grandfather clock I've ever owned much less done a full breakdown, clean, repair and reassembly. It's exciting! While I will detail a bit of the disassembly of its movement, I'm going to focus for a bit on the amazing strike of this DUFA. Beyond its beautiful tone, the mechanics of the strike really tickled the gray cells of this engineer. It turned out to be quite a learning journey. Some clocks strike the hours with a single beat, repeated to count each hour. The  dog clock  does this. A single hammer strikes its bell once for 1pm, twice for 2pm, etc. A very common and lovely-sounding design of many a French clock. Our DUFA strike is what is called a Bim Bam  or Normandy style. The Brits call them Ting Tang.  Think "ding dong" like a doorbell. Bim Bams count the hour by striking two different tones in pairs for each hour. Ding dong for 1pm.  Ding dong, ding dong for 2pm.  Etc. The DUFA box clock also has a Bim Bam strike,...

When we last reviewed our DUFA friend I noted that the movement looked to be in good shape and I was about to embark on a cleaning. A practical approach to cleaning starts with a disassembly and simultaneous deep inspection. Diving in... It appears that someone tried to make a repair on the movement's suspension spring. You can see the suspension spring glittering above on the upper right.  Likely the suspension spring broke by some form of rough handling of the pendulum. The home-brew repair effort speaks to the repair person's inexperience with mechanical clocks. Not to sound smug... it's just that the results speak for themselves to the trained eye. Suspension springs use very thin, highly-flexible "wires" (metal strips), often in pairs. The thinness and flexibility of the suspension wires is key.  A pendulum must oscillate and be able to receive power from the escapement easily. In most clocks the performance of a pendulum is greatly enhanced by the use of a ...

A fair bit of internet research on the sculptor, Cartier, and variations of Dog and Clock bore some fruit. From a long ago Australian auction house offering: Note the metal decorations on the front and the minute hand appears to be missing. And from an English auction site: The dial, bezel and hands are distinctly different. I took another look at our canine example and now something I'd not noticed before. Look closely and you'll see the hole repairs from where the metal adornment had been removed. I prefer it that way. I did polish the bezel up but took a very light touch to the case and the statue. Keeping to a gentle cleaning with water, I wanted to retain what was left of the gilding of the statue and the marble was in good shape. She's been running happily for months and is a good time keeper.

Off with the plates. For the most part removing the wheels and such is very straightforward but I do like to capture each wheel removal to ensure I know the corresponding pivot hole. Guessing afterwards, what goes where on the plate, could be a long game. The Brocot suspension was in fine shape. The suspension spring itself was a little bent but I've come to understand that with gentle straightening is will not effect the functioning of the clock. That notch in the brass end on the right... classic French, Brocot suspension spring . It's designed to clear the edge of the adjustment wheel on top of the unit. Here it is installed before cleaning. Held in place by a pin going through the unit (right below the adjustment wheel) and then down through adjustable plates. The arrow is pointing to the very top of the suspension spring and the notched part is facing inwards and is under the adjustment wheel. Now to clean the parts of the movement. Base grime removed by hand. I used Dr. J...

I mentioned the care needed in disassembly. Here's another example. In our last episode , as I removed various parts of the dog clock movement, I discovered a very unusual spring. Continuing our movement disassembly I spied another. Pictured below are a couple of lifting levers for the striking mechanism. Under the shorter one is a wire, seen here protruding just above my thumb. It appears to be another example of the use of a wire spring in a way I've not seen before. It threads from a tiny hole on the top of the lifting lever, around its arbor on the right, then across the bottom of the lever and the front plate, then down through a tiny hole in the plate and is bent on the other side to hold it in place.  Wires are commonly used as springs in clocks but less commonly in French clocks and I've never seen one like this. The function is to serve as a spring, pushing the striking lever back in place after a strike of the movement. Striking referring to striking the hour: 2 s...