We have had a few determinations of legitimacy of watches made using the material of the stop lever (a.k.a. the brake) lately, and sometimes it's not so easy to tell what the material is, so I thought I would post some information that might help.

This is a metal brake from a Cal. 861 - my own watch:



You will first note the colour is grey as it's made of steel. It is also made in 2 pieces, so where it contacts the cam near the top of the photo you can see the bottom piece sticking out from under the top piece, and a definite line that shows you it's one piece on top of another. Sometimes photos are not ideal with the white balance off, and sometimes photos are dark, so these are not always good enough indicators, so I have added a red arrow to the post that interacts with the hammer for comparison.

Now let's looks at the plastic brake from another 861 I have in the shop right now:



In this one the brake is bright white so it's easy to see it's not steel. Sometimes these can get stained to look quite grey, but the most common discolouration is for them to yellow as they age. You can also see the plastic version is all in one piece, so there is no "step" near the contact point for the cam like there is on the steel parts. But again I have highlighted the post - note that unlike the steel brake, this post is not cylindrical, but is more lobe shaped.

So looking at these 3 specific features, plus watching for things like bright reflections off parts of the brake (won't happen on plastic like it does on steel) can usually give me a pretty quick idea if the brake is plastic or steel.

Hope this helps.

Cheers, Al

 

A useful data point - thank you!

 

Thank you!

 

Awesome, thanks Al.

Anyone got a wider pic of an 861 to put the brake in context?

 

See the red oval


BTW This photo was taken before a service so it's cleaner now...

 

Might make it easier with the whole watch shot

 

Here is another plastic, slightly different color

 

I think mine is made of aircraft grade billet plastic.

 

I know all the benefits of the plastic part, I've heard it a million times, but it still bugs me somehow that a decent quality watch uses it.

 

Some info here on the Delrin part

http://chronomaddox.com/omega/articles/delrin.html

 

The description in there is a stretch. People calling it a brake implies that it is involved in stopping a part that is moving, and really it's not. The only time it is active is when the chronograph has been started, then stopped, but not yet reset. It's not like a brake pad that uses friction to stop something - it's only there to keep it from moving before the chronograph is reset. The brake comes fully off the wheel before the hammer comes down to reset the wheels.

The advantages of this over the steel version are mostly imagined, other than saving costs of course.

Cheers, Al

 

Now where have I seen that one before