Hi All,

I have a Wakmann 8day clock which came from a Cessna 152 aircraft.
I need a mainspring for it but have been totally unable to find anything suitable.

It's a white metal reverse coil job, dimensions 4.97mm Height, 0.18mm Force and longer than 51cm (barrel inner diameter is 17.92mm).

I say longer than 51cm as that's all I've got left of it.
Having tried a few times to form a new hole and coil for the arbor hook unsuccessfully (always breaks across the hole), it's getting a touch too short now for an 8 day clock - will be more like 8 hours at this rate.

In the absence of a new spring, has anyone ever successfully formed a hole and coil on this material?
I've tried both punching and grinding the hole then finishing with fine diamond files, but as soon as I start to form the coil, it cracks across the edge into the hole!

Any suggestions (nothing outlandish please) or pointers to supply of a correct spring would be most appreciated.

Many thanks

John

Outer Coil of Mainspring.

John

Movement.

Engravings on the bridges state -
Wakmann Watch Co, Swiss, 7 Jewels, 3231093

(incomplete as only partially assembled for photo's).

John

Caseback with Cessna details.

John

I think your movement is a Lemania 7510-7511
that was used by many companies.
You might post a request for it by this ID.
J Smith

Appreciate the lead Julian, many thanks.
Will do some research down that route and post what I find.
Regards
John.

The movement is indeed a Lemania 7510 (the 7511 is the 24 hour version), thanks again for that lead.

I found the movement listed in my Bestfit books, complete with diagrams and listings for balance and pallet staffs, plus rollers and tables etc, but absolutely zip for the mainsprings - no sizes, no cross references, no interchangeability.
So, looks like I'm back to sq1!

I was able to post a couple of 'wanteds' on websites, but no joy so far! Seems a few folks are looking for bits for this Cal movement!

Anyone ever succeeded in punching or grinding a hole in alloy mainsprings - then re-curving the end (barrel arbor) without cracking it across the hole?

John

Borel lists a spring as best size ---6-3.5-18
Wittnauer used this caliber as cal 90,if it helps.

J Smith

Many thanks again, I'll follow this up, see what I can find.

Regards

John