Strutt Epicyclic Train Clock (maybe?)

[Kim]

More nice parts coming along! 

Kim

[kvom]

Two parts for today.

The first is the 'sun wheel boss'.  One end is a sliding fit into the center hole of the dial, and the other end mounts the stationary sun wheel.  The three are fastened together  by two 0-80 screws, with the dial having the tapped holes.

The second is the 'hour wheel cannon'.  The hour wheel is attached to it by three 0-80 screws.  The long portion goes through the center of the sun wheel boss, placing the two wheels close together so that both engage the same lantern pinion.  The hour wheel revolves once per hour, and the attached cannon protrudes through the dial to permit attachment of the hour hand.  The through hole in the center of the cannon allows the center arbor to pass, and it will attach to the minute hand.

[crueby]

I remember the  first time I  looked at clock plans, the minute/hour train was very confusing. Nice progress!   

[kvom]

I had been confused about how this type of clock is wound, as I figured turning the barrel arbor would wind the spring. But then how does the string get wound back onto the fusee.  It seems obvious, but you wind the fusee arbor to load the string back onto the fusee and at the same time rotate the barrel.  The barrel arbor has a ratchet, and is used to preload the spring.

I found this YT video, that shows the disassembly of an antique fusee movement, with lots of good information.

<a href="https://www.youtube.com/watch?v=7X51V1qF960" target="_blank">http://www.youtube.com/watch?v=7X51V1qF960</a>

[kvom]

Short session today as I had a dentist appointment earlier.  The single daily part is the 'spider collet'.  It attaches to the 6-legged part that mounts the ring wheel.  Three tapped 0-80 screws are used.  The center arbor passes through it lengthwise.

[crueby]

Very unusual clock gear setup with both external and  internal  teeth. 

[kvom]

One tiny part this afternoon, the 'escape wheel collet'. 

I just noticed I neglected to chamfer on edge, so I'll do that next time in the shop.

[Kim]

One tiny part this afternoon, the 'escape wheel collet'. 

I just noticed I neglected to chamfer on edge, so I'll do that next time in the shop.

Chamfers are what separate us from the animals! 

You're getting a good number of pats made for your clock! 

Kim

[kvom]

I started on the 4 pillars that join the front and rear plates.  The bottom pair are larger in diameter than the uppers, and all 4 need to be the same length.

The uppers, according to Smith's drawings, would be 1-3/16" in diameter at the widest.  I don't have any brass rod with that diameter, but do have several pieces of 1-3/16 square bar.  I mounted my (heavy!) 4-jaw chuck on the lathe and attempted to center the bar using a digital indicator.  Try as I may , I was never able to get it perfect straight and centered.  So after turning it down to round I ended up with 1-1/16" rod.  This is convenient as I can use a lathe collet of that size for finishing.  Since square bar won't fit into my lathe's bore, I was limited to turning down 5.9", which is enough for two pillars.

To separate the two piece I use a 1/16" grooving tool to cut two shallow groves that I used at my horizontal bandsaw to indicate where to cut.

The upper pillars need only 3/4" rod, which I have already in stock.

Next time I'll start to turn the profiles.

[kvom]

No shop time today, but I wanted to summarize a few things about this type of clock that I've learned recently.

Winding

A fusee clock mainspring is not wound by turning the barrel arbor.  Rather, the fusee itself is wound.  The fusee shares an arbor with the great wheel, and there is a 1-way ratchet and pawl between the two.  So then turning the arbor to wind the clock, the fusee turns while the great wheel does not.  Turning the fusee pulls the chain/cord that is wrapped around the mainspring barrel. and in so doing turns the barrel.  As the barrel arbor is fixed, turning the barrel compresses the mainspring.  The barrel arbor itself is prevented from turning by a ratchet and pawl on the back of the clock.  This arbor CAN be turned if needed to take up slack in the chain, as it can be difficult to size the chain in advance exactly.

While watches and some clocks did use an actual tiny chain, here the clock will use a string made from gut (or a synthetic equivalent).  Wire shouldn't be used as wrapping around the small end of the fusee will eventually cause it to fray.  Both ends of the string are attached by passing though holes in the barrel and fusee and tied in knots too large to pass back through the holes.

Running

As the clock runs, the great wheel turns, and its ratchet turns the fusee along with it.  The barrel turns and maintains pressure on the chain as it winds off the fusee and onto the barrel.  Here the fusee has 18 grooves.  If the great wheel turns twice per 24 hours, the clock should run for 9 days, assuming the chain is long enough to fill every groove and the spring is strong enough.

The great wheel turns the center pinion which is on the center arbor, and thus supplies all of the torque to move the rest of the mechanism.

Escapement

I hadn't realized it until this past weekend, but the anchor interacts with the escape ratchet not only to meter the pace of the clock, but also to keep the pendulum swinging.  So the tips of the anchor need to push on the teeth of the escape wheel to impart energy to the wheel and then to the arbor that connects to the pendulum.  This requires careful fitting of the anchor tips to the wheel.

[crueby]

The last thing about the escapement is really key too everything - the pendulum will gradually slow down unless its given that little nudge on each tick - doesn't take much.

[Kim]

I went through that same chain of logic as you did here when I was trying to figure out how my clock worked!  Each and every point! 

It is fascinating to learn how all this stuff works!

Does your clock have a maintaining mechanism that keeps the clock running while you wind the fusee?  That was another added level of complexity on my build that I had to get my mind around.

All very interesting!

I'm enjoying watching your build come along.  Your's has a really unique setup for the gear train for sure! 

Kim

Kim

[kvom]

Does your clock have a maintaining mechanism that keeps the clock running while you wind the fusee?  That was another added level of complexity on my build that I had to get my mind around.

I don't think so.  I did see a video about a fusee watch where there was an extra spring to keep the watch running during winding.  But unless the clock is extremely accurate I'd guess the few seconds needed to wind won't vary the timekeeping greatly.

I'm following your build too although I don't comment often.

[crueby]

Does your clock have a maintaining mechanism that keeps the clock running while you wind the fusee?  That was another added level of complexity on my build that I had to get my mind around.

I don't think so.  I did see a video about a fusee watch where there was an extra spring to keep the watch running during winding.  But unless the clock is extremely accurate I'd guess the few seconds needed to wind won't vary the timekeeping greatly.

I'm following your build too although I don't comment often.

The maintaining mechanism was most important for things like marine chronometers, where a few seconds per wind could add up to being miles off course over months of voyage. For a mantle clock, not so important! 

[Kim]

Does your clock have a maintaining mechanism that keeps the clock running while you wind the fusee?  That was another added level of complexity on my build that I had to get my mind around.

I don't think so.  I did see a video about a fusee watch where there was an extra spring to keep the watch running during winding.  But unless the clock is extremely accurate I'd guess the few seconds needed to wind won't vary the timekeeping greatly.

I'm following your build too although I don't comment often.

The maintaining mechanism was most important for things like marine chronometers, where a few seconds per wind could add up to being miles off course over months of voyage. For a mantle clock, not so important!

But super fun and cool, nevertheless!