Friday, September 27, 2024

Repairing a Vintage Glycine Airman

 Here we have a 1957-ish vintage Glycine Airman, the OG pilot's watch (or at least the most infamous), powered by the excellent Felsa 692 movement.  

I say "infamous" because the watch seems to be best known for its unique, if crude, seconds hacking mechanism.  Maybe mechanism isn't the correct term, let's say "device".  In any event, they are very often broken/inoperative.  This situation is almost always (actually, always) caused by the machinations of either those who are unfamiliar with the design and are not expecting what they find, or those who are just fumble-fingered dolts, who don't really give a s**t.  This watch was clearly the victim of the latter.

The hacking device in the Airman is simplicity itself: a lever, pivoted roughly near its middle, is engaged at one end by the winding stem (which is modified to provide a "groove" into which the lever slots) and at the other end, attached to a small (VERY small) wire.  This wire protrudes through the dial at the top center and, when the lever moves about its pivot, the wire is either pulled downward, clearing the seconds hand, or pushed upward, thus interrupting the movement of the seconds hand.  

This device imposes its own disassembly and reassembly method: one does not simply release the winding stem and yank it from the watch.  Side cutters most certainly are not called for, yet were apparently employed at some point, as evidenced by the damage caused to the original hacking device.  As well, the wire that does the actual stopping of the seconds hand was broken off.  So, with the stem-end of the lever snipped off and the wire broken off, I was left with little choice but to make a replacement device in its entirety.  

The original lever is made from round wire, ground flat on one side, and with a "squashed" area to provide enough material for the pivot screw threads and for the stud that holds the wire.  I'm certain it was the most efficient design from a production standpoint but, since the replacement is a one-off, I was going to be a little less caveman about it.

This what it looked like when uncased (yes, it came in with the stem removed).

 

The casing spacer was a bit worse for wear as well but easily corrected.


 I made a pantograph pattern at 10X that would give a "blank" part, meaning that the holes would be located and the proper curvature established.  After cutting the blank, the pivot hole is tapped and the lever is fitted to the stem.  With that done, the next step was to turn the stud for the Nitinol hacking wire, create the aperture for the wire to pass through the stud, then assemble it and adjust the height of the wire's protrusion through the dial.

Turning the stud...

The finished lever...

The movement was also serviced while it was here.

I installed a new crystal to replace the cracked original, reassembled it, checked it on the timegrapher and it's ready to go back home.




Sunday, September 8, 2024

Shop-Made Tools

 Here we'll take a look at some of the tools that I have had to make in order to perform a specific task.

Sensitive/Uprighting Drill Press/Mill:

After searching for a drill press that had enough sensitivity to drill holes sometimes smaller than .010", without destroying drill bits (or the part being drilled) and finding that there were few options, I decided to make my own.  The criteria was simple enough: spindle runout and perpendicularity as close to zero as possible.  Achieving that took some effort but it was well worth it.  Spindle runout is .0004" (4 ten thousanthsof an inch) and perpendicular error is .0002" (2 ten thousandths of an inch).  The finished item may not look too impressive but its performance certainly is, and that is what matters.  When mounted on its drive base, the spindle speed is controlled with a Foredom foot pedal and the spindle is controlled with the non-rotating knob (it's ball bearing mounted) at the top.  An adjustable depth stop is mounted on the spindle as well.  The spindle is 8 millimeters in diameter and will accept any tool with a .125" diameter shank.  I have also made numerous cutters with an integral spindle that replace the drilling spindle entirely.  The spindle is supported in two precision ball bearings mounted in the upright.

When removed from the drive base, it also serves as a precise reaming tool that accepts the Seitz reamer holder.  I've also used it to create perlage, though it's probably a bit much for that application as far as precision goes.

Geneva Stripes (Cotes de Geneve) Tool:

In George Daniels' book Watchmaking, a tool similar to this is described.  That one however, is made of wood and the part's height is adjusted by "packing" it with shims.  I wanted something a bit more sturdy and precise, so mine is made of steel and the stage upon which the part is attached is height-adjustable via screws.  The guide pins are spaced at .125" intervals, which create stripes of the same width.  By using .250" diameter sleeves over the guide pins on alternating stripes, uniform .062" wide stripes can also be created.

These photos and video show a test piece (actually part of another tool)

Here are some actual parts:

Rotary Positioning Stage:

This tool is useful for a number of tasks.  There are sixty, equally spaced detents around the periphery of the center "wheel", which is mounted to its base in a precision ball bearing.  The spring-loaded detent holds the wheel in position with enough strength to allow milling of a part attached to it.  It's handy for drilling minutes and seconds rings and milling equally spaced repeating patterns, as well as perfectly spaced perlage.

Various Cutters:

Rarely will an off-the-shelf cutter work for any task more complex than simple stock removal, so when a cutter is needed for a specific task, it must be made.  Here are some that I made for a particular project.

Balance Poising Tool:

There isn't much to say here, it's a pretty simple tool: a pair of hardened, knife-edge steel jaws that are parallel in both vertical and horizontal planes, adjustable for opening width, and mounted to a three-point adjustable base for leveling (the ends of the leveling screws are radiused and polished).  The jaws are made from hardened 1095, rather than ruby as on the prettier tools.  Don DeCarle saw no disadvantage to steel jaws and, since he knew a hell of a lot more than I do, I'm in no position to argue.

"Horia"-Style Jeweling Press:

I don't know if anyone else ever wished for a bit more space under the ram of a Horia tool, but I often do, so I made this.  The ram is supported in two precision-reamed Oilite bushings and the micrometer head is retained by a tapered split collet and nut arrangement, ensuring its concentricity.  The table is much larger and the T-slots allow for "extra hands" when needed.