Old Aviation Panel Clock disassembly?

MuseChaser

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When I'm not working on clocks, I'm flying my PA28-140 Cherokee and occasionally working with two wonderful A&P/IA guys (certified aircraft mechanics) on various airplanes. Today they gave me this old panel clock to try and repair. It seems to be running OK, but they said it kept stopping in flight. FIgured I'd at least attempt a good disassembly and cleaning, but I'm unsure how to proceed. The only timepiece I've done other than torsion clocks and mainly American time/strikes is replacing a cheap quartz movement on a late 1970s Majesti pocket watch.

Anyone have any experience with these who can advise me on disassembly? The "certified" TSO/PMA/STC/etc. ..nature of aircraft parts isn't an issue here.. this isn't going back in an airplane, so for anyone who's up on FAA regs, no need to worry here.

7fd50984-2d70-4e8e-952b-7c49968a2c6d.jpg 78f4482c-491c-4320-9ffd-d2f8eaa5f8a1.jpg
 

shutterbug

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It looks like there might be a ring around the bezel that comes out to release it from the front.
 

Schatznut

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If you can get the two smaller caps off the back without boogering them up, I'll bet you find hardware that will release the can from the back.

That would make a nice pairing with a Kollsman altimeter out of a C-121 someone gave me a long time ago... Makes an interesting barometer - just set it to the local altitude and read the barometric pressure in the window - just the opposite of how it's used in an airplane.
 

MuseChaser

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Thanks, Schatz und Bug. I'll give it a shot. The hands don't look quite as fiddly as the ones in the pocket watch (those were tough, esoecially the second hand), but I confess I'm a little worried about the movement itself. I don't have any watch-repair-specifi tools, nor experience with watch springs, hairsorings, balance wheels, or whatever else I might find in there. The brass knob in the lower left of the front pic above winds the clock, and when pulled out sets it. The mechanical clock in my plane is similar, but has an added push button that starts, stops, and resets the second hand and an additional minute timing hand. At least this clock doesn't have that additional complexity.

Do I have a shot at this?
 

Schatznut

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You'll find out when you get it open... ;) I bet you'll be able to do it. That it was made by Wittnauer, a watch manufacturing company, suggests it may be built more like a watch than the clocks you and I are used to working on, and that's a good thing. You may find that the balance wheel and motion trains are contained in their own separate bridges and you will probably find the movement is jeweled. If the balance wheel is in its own bridge, you may opt not to disassemble it; just the rest of the mechanism. When you clean it, especially if it is jeweled, consider using white gas (Coleman fuel) as it flashes off quickly and leaves no residue. I'm interested in riding shotgun with you on this one - looks like fun.
 

MuseChaser

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Will definitely keep you posted and will take a lot of pics. The clock is still running after a partial winding yesterday at about 1pm (approx 22 hours ago). Just to be safe, I thought it'd be a good idea to let it wind down before opening it.

Just sent you a pm, too. Thanks for the encouragement!
 

MuseChaser

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'Bug's tip on the bezel ring was dead-on. With that tip, removing the glass and accessing the hands was easy, although the clock is still running so I didn't remove the hands. Here's two pics..

WittExplode.jpg WhichScrews.jpg

In the pic directly above, the yellow arrow indicates a small screw that rotates as the winding knob ("crown?") is rotated, so I'm guessing that holding that screw still while rotating the winding knob the opposite direction will allow me to remove the knob. The balance wheel/spring/whatever it's called can be seen oscillating in the opening at around 11 o'clock in the back. Should the screws indicated by the green and/or blue arrows be loosened or removed in order to take the movement out the front of the case? I'm afraid to undue something and have the whole mess come apart before I can take pictures to remind me of how it goes back together!
 

Schatznut

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Having worked on avionics for a good many years, I've found that if a screw is accessible through a port it's meant to be accessed. It depends on whether it secures something or is part of an adjustment mechanism. The two in the lower right probably release the mechanism for the knob on the front. The other two probably secure the front flange to the case. Of course, the port for the escapement adjustment - that will become important after you've gone through it. I seriously doubt it will all fly apart on you...
 

roughbarked

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When I'm not working on clocks, I'm flying my PA28-140 Cherokee and occasionally working with two wonderful A&P/IA guys (certified aircraft mechanics) on various airplanes. Today they gave me this old panel clock to try and repair. It seems to be running OK, but they said it kept stopping in flight. FIgured I'd at least attempt a good disassembly and cleaning, but I'm unsure how to proceed. The only timepiece I've done other than torsion clocks and mainly American time/strikes is replacing a cheap quartz movement on a late 1970s Majesti pocket watch.

Anyone have any experience with these who can advise me on disassembly? The "certified" TSO/PMA/STC/etc. ..nature of aircraft parts isn't an issue here.. this isn't going back in an airplane, so for anyone who's up on FAA regs, no need to worry here.

View attachment 654368 View attachment 654369
As to stopping in flight, apart from the good overhaul of the movement itself, I'd look at replacing whatever rubber mountings there are and as for the plane it is meant to be used in, check the balance of the engine.
 

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