Elgin Convertible Grade 50

This simple, useful and surprisingly expensive tool is not a Borg action figure.

In this case, working on an Elgin convertible pocketwatch, there was some trouble getting the center shaft out of the center wheel tube. Usually this is done from the back side before taking anything else apart, but on this one the cannon pinion and the tube where tight and a tiny bit corroded.

It was necessary to carefully lift the bridges off, then remove the center parts. The various size holes in this steel block provide exactly the right support.

An Elgin convertible model can be assembled either as a hunter movement, stem 90 degrees to the seconds dial, or as an open face movement, stem 180 degree from the seconds dial. Note how the main plate has two cut-outs, 90 degrees apart, for the winding arbor.

This one is getting assembled in hunter configuration.

For the train wheels, there is only one possible configuration. The only difference between hunter and open face setup is the location of the stem.

Also, in these images we can see that the center wheel arbor is a hollow tube. That is where the setting arbor goes, connecting the cannon pinion on the front (ie. the hands), to a setting wheel on the back. The watch is lever-set. Pulling its lever out causes an exposed wheel to lift and engage the setting wheel on the back, putting the watch in setting mode instead of winding mode.

Hands very often do not fit quite right, even factory original parts. Hands are friction fit and often the holes are too small or too large. The techniques for adjusting minute hands, hour hands, and second hands are all different because the hands are all different.

In this case, a minute hand needs a bit larger hole. There is this vice with many hole of different sizes that holds the "boss" end of the hand, and a cutting brooch of used to slowly enlarge the hole by very small amounts, with frequent testing, until it it right.

I don't know if there is a reason, but the convertibles are, I think, the only Elgin pocketwatch grades the use three case screws, rather than the usual two (or one in the really old ones).

This watch is a grade 50, 16 size, 15 jewels, made about 1885.

Find more about Elgin's convertible movements here!