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Marc Tovar sent me a jpg of a gear set that he wants to make into a “watch”.  Rabbit has made an absolutely incredible one which you can see at

http://flashpages.prodigy.net/rpirtle/_ufiles/detail_watch.html

  The picture of the watch in his hand is a computer aided one because the watch is actually 10 1/2” in diameter, still it is one beautiful time piece.

The challenge for me in this unit is to build the balance wheel escapement and to build it in a 6” case and finally to cut all the parts on my CNC unit.  (There has to be some reward for the frustration involved in building the CNC.)


The dial is painted on the glass so that all the gearing is visible.  The inside of the case has been painted white to give a better view of the inside of the clock.

This is Rabbit'sWatch not mine!

(link is above)

with a little computer enhancement of the 10 1/2” actual unit

The gear set is really straight forward with the exception of the escapement  which uses a balance wheel and hair spring.

As a concept I think the wheels could be laid out like this.  I would like to have the second gear which is the center wheel in the center but that will add to the overall dimension.

The “CNC Cutting Station” is pretty messy but the only part that matters is the CNC table on the right.  That is where the parts are born.

The CNC allows a pretty efficient use of the wood as you can cut very close to other pieces and the edges of the wood.  On the other hand at 5 minutes a wheel you tend to cut extras!

The “Watch” has three pinions - two 7 leaf small ones (1/2”) and a larger 8 (0.6”) leaf pinion.  The pallets on the left are for the balance wheel escapement.

If the depthing gauge is any indication this will be a very smooth time piece.  But there is still lots left to do.

I have all the wheels cut out, this mock up shows how I think the train could be laid out, with some concentric circles underneath.  


Looks like 6" is a good size.

Back into CAD to shift around circles that represent gears and pinions, I was able to fit everything at about 5” so that a frameworks around the watch would be at 6”

I applied what little artistic talent I have to come up with a pleasant looking plate for the works.

From CAD I can get the center to center measurements for the gears.  I much prefer to use the depthing guage and measure between the pins.

This a first pass at mounting the wheels in the plates.  All the arbors and plate bolts are left long for ease of assembly and dis-assembly at this stage.

The 1 and 1/4” between plates is plenty for the gear train with a little room for adjustments

The balance wheel is not mounted at this point.  There needs to be a straight line from the escape wheel to the pallets & to the balance wheel.  In order to do this the great wheel needs to be relocated.

I missed the arbor for the balance wheel so the plates have been recut and the balance wheel is in place, as well as a small movement of the great wheel to make a little more room

Looking between the plates you can see the hair spring that I made out of 0.007 Piano wire. (No science here just thin wire)  With “finger pressure” on the great wheel the unit “tics”

This is a close up of the home made hairspring.  The wire is really fine and really difficult to adjust.  I need to rotate the whole spring assembly to get a good beat

I tried a whole multitude of balance wheels and this one is working the best.  It is a 2 in diameter 1/8” thick unweighted wheel.

I opened up (cut away) some of the front frame for a better view of the escapement.

The Springs have arrived and these are the parts to make a spring wound mechanism

The click is attached to the great wheel and mates with a rachet, the spring is next and then a gear.

It is easier to have a squared arbor away from the main wheel, and the spring is attached to a central shaft that rides over the great wheel arbor

The winding gears are cut.  Now the central shaft needs to be turned and the square arbor for the winder.

The central shaft which has been center drilled for the arbor and then cross drilled for 1/8 “ brass pin for the spring

The spring is a part number 16766 in Time Savers a 5.16 X .010 X 28 Hole end Mainspring.

The anchor end of the mainspring is on the frame of the clock.

I decided to back away from a spring, while it works, I am not experienced with them and portability is not the name of the game.  My watch will most likely be weight driven.

The back of the case is “engraved” with a floral motif that is just under the 6” diameter of the watch

The sides of the case are about 1/8” thick.  it is formed in 3/4” layers.  The dark wood is a “mold” around which the arc pieces are glued.

The case of the clock is made of plamed maple and I applied a dark walnut stain.

The sides of the case have been applied.  I would have been nice to make them rounded but there are other clocks to build

Hanging on the wall the 5” curved glass face in place.

The back of the clock isn’t normally visible as it is against eh wall

The plates are stained yellow so that they can easily be seen through the glass front.  This view is without flash and the gear works do not stand out.

With a flash all the gears show well and with the curved glass there is not flash reflection - bonus!

Now on to the time train.

Starting work on the time train.  The great wheel make a revolution every 15 minutes.  The time train then has 2:1 for an intermediate and another 2:1 for the minute hand.

The hour hand will need a 12:1  so I’ll put in a 5 pinion to a 15 gear for 3 and then a 5 to 20 for the four.

The dial is painted on the glass so that all the gearing is visible.  The inside of the case has been painted white to give a better view of the inside of the clock.

The time train is complete and its 10 past 7