Pocket Watch Main Spring Problem

[BYJWR1]

Hello Bob and fellow Members

I am in the process of cleaning and restoring an Elgin size 18, 1907 vintage, 17 jewel, open face pocket watch
with a stem wind and time set. One of the problems that I have encountered is the way the main spring and
winding arbor are hooked together. I am more familiar with the main spring/arbor hook arrangement/designs
of clocks, where the spring is easily attached to a hook on the arbor. With the pocket watch, I don't see anything that resembles a hook on the arbor. What I see is a small slotted or notched area on the arbor with a slightly elevated square.
I am assuming the elevated square is the hook and the spring is some how press fitted over the square.
I would appreciate some input on the design of the pocket watch arbor hook/main spring arrangement and how they
are put together with out having a slippage problem when winding.

Thank You
BYJWR1

[Bob Tascione]

Hi BYJWR1,
Yes you are correct. There should be a slight forward taper to that square which acts as a hook to catch the mainspring. The notched area allows for the hook and starting end of the mainspring to lay down below the outer surface of the arbor eliminating a bump from the end of the mainspring and hook that would be present without this setup. If there is no taper then it's possible that the hook has been damaged or worn off.
Enjoy!
Bob

[BYJWR1]

Hello Bob,

Thanks for the reply! Please let me know if there is a way to reestablish the forward taper to the square (hook) for
the main spring to hook onto?

Thanks

BYJWR1

[Bob Tascione]

Hi BYJWR1,
Yes often times if there is enough material left you can use a knife edged or small escapement file to reshape a small taper.
Good luck BYJWR1 and please let us know the outcome.
Enjoy,
Bob

[clam71]

I can only speak from my own experience (limited) from
working with Waltham pocket watches.
My size 18 vintage 1888 needed a mainspring.
I found one on ebay for about 20 bux.
These springs fit into a "drum" and the outside of the spring
has a small "T". The inside has a small square hole.
Be careful about which way, clock-wise or Vise-versa it goes.

Attached is a pic of my 1888 lever set Waltham.
Bob, the master, is correct (always) in that a fine file and steady hands
can renew the catch on the barrel hub so the spring doesn't slip
off. It's canti-levered a wee bit so that the spring holds tightly
to the hub.

I hope the pic helps all out there who may have similar issues.

[BYJWR1]

Hello Bob and Clam 71

Thanks for your replies which were very helpful and appreciated! I was able to address the problem by dressing up
the hook and re shaping the main spring at the arbor end. I found that shaping the spring to fit around the arbor
and have it hook onto the arbor hook was critical! It had to be a very tight fit.

The bottom line is, I put the barrel with spring back together again and was able to wind the spring and it worked
just fine.

Thanks again!

BYJWR1