This clock was designed byDavid Atkinson. The clock is available in various forms everything from a complete kit with all CNC cut parts ready to assemble except for the final drive weights.
The motion of the double pendula appealed to me with its segmental gear coupling giving it a "Steam Punk" appearance in my opinion.
I opted for the dxf digital format. Getting an electronic file only.
The first task I was faced with was the conversion to "Imperial" sizes since the original was all metric.
The second challenge was the material dimensions - the plywood thicknesses are not available here nor are the brass rod dimensions for the arbors, this was also converted to sizes available to me.
The dxf file showed the pieces in 7 "sheets", which was the right size for the small sheets of baltic birch available at hobby stores.
For 5 of the 7 sheets I used 1/4 inch baltic birch as I have it readily available and for the two frame sheets I used 1/2 in bsltic ply.
All CNC cutting was done with a 1/16 inch end mill.The dxf file showed the pieces in 7 "sheets", which was the right size for the small sheets of baltic birch available a hobby stores and perfect for my 24" cnc.
All CNC cutting was done with a 1/16 inch end mill.
The Frame was glued using white furniture glue and the glue-up was done on the table saw along with a square.
By having the instructions that were supplied with the dxf I was able to get the frame pieces glued together in the proper orientation.
This cut is from the first sheet of drawings, I labled each piece to match the dxf sheet making parts easier to identify. All the holes were resized to 1/8 inch as I can easily make them larger if needed. David called for several arbor sizes and all in brass. I don't have access to the sizes called for so I changed the arbor sizes either 1/8 or 1/4 inch piano wire which I can easily obtain..
Although there are lots of arbor holes to be resized all the "cut outs" could be cut without alteration.
On the second sheet like the first I only had to change the arbor size
The third sheet had the gravity clicks included which I cut but will likely not use. David had changed the "clicks" from gravity type to wooden spring type. No scaling was supplied for the spring dxf's but a ratchet was part of that drawing, a comparison and cut of the ratchet showed by types to use an identical ratchet.
I cut the ratchet from sheet 3 and the "new clicks" sheet and they were identical so either click type will work.
The new clicks are a positive type that is always engaged with the click wheel.
I cut these "spring" clicks and both ratchet wheels just for comparison.
As before arbor sizes had to be changed.
The frame is assembled with the main members stained and varnished.
The frame spacers started as 1 1/4 inch dowels, which was then turned down on the lathe to match the metric sizes that were CNC'd from the dfx tile.
By first drilling the center to 5/16 I was able to centre the dowel on the lathe and have an easy fit for the 1/4 inch ready rod and a perfect fit into the frame.
Furniture connectors instead of sleeves was used on the ready rod since sleeves were not readily availabe here. They worked very well.
The first gear installed is the drive which I have put on a 1/4 inch steel arbor. Insteqd of drilling the arbor to take a pin for the winding crank I choose to slot the shaft as it was easier (I have broked many, many drills trying to drill rod} for me to do. The engaging pin will be on the crank for winding.
Using a grub screw on the winding drum has always given me problems with stripping out in the wood. With a nice large drum to hold the drill bit registered it was very easy to center drill the arbor and use a steel pin through the arbor - it will never slip. (Looking back if I used a pre-drilled block I could make a centering jig for rod drilling!)
(One note the diameter of the winding drum is not shown anywhere except the materials list)
The frame was mounted on a bench test frame that I use for nearly all my clock constructions.
All the arbors for this clock with the exception of the 1/4 " main winding arbor are 1/8 inch piano wire.
Now one by one the gears and pinions were assembled, glued and installed in the frame - no adjusting was necessary
The clock face is screwed on the frame - the location holes are by measurement and not CNC'd into the frame. Since the location of these holes is not critical to the clock movement super accuracy doesn't matter. The stand-off is simply a brass tube over the mounting screw.
I have found that getting the gear, spacers, and pinions all square is a lot easier if I put an appropriate arbor in the chuck of my large drill press and mounting the items on the arbor to apply glue works really well.
The table of the drill press is nice and square with the drill arbor and being the tab;e being gear driven a square pressure can easily be applied and the glue left so set. I have tried other methods in the past but none have been more successful.
Normally I would put the larger gear down on the table the other components would square to it - but in this case the arbor clutch maks this technique impractical.
With the complete running train and the time train install there is only the pendula left to install. It passed the "blow" on the escape wheel test>
This side view shows the time train all nicely arrange from back to front with the escape wheel mounted outside of the front frame.
Although these glued up pendula gears look fine THEY ARE NOT and I had to cut new ones on the cnc so that they could be assembled correctly
The pendula were previously assemble and shown here on their arbors.
This photo shows the gear drivers to the pendula - BUT - the right gear "hooks upward" while it must hook downward to function correctly
OK recut the palet partials andglued them correctly on to the clock.
Everything hangs correctly now.
I haven't used any bearings yet because my experience with all my other clocks (34) have shown them not only to be unecessary but difficult toget them to work as planned. BUT using the recommended weight it wouldn't run.
This shows the finished clock with 1/8 inch ball bearings installed on the pendula. The running weight is approximately 6 pounds and the clock has been running for about 6 hours.