Hi Omega forum, long time looker first time poster.
I have dabbled for a while with watches and have some questions for the watchmakers of this forum.
First Question....
Is there a specific tool for slightly bending watch hands without damaging them? (Some watches have the chrono seconds hand bent from the factory and only offer the replacement hand straight)
Second Question....
I resently purchase a cosc ETA 7750 barrel complete and was wondering if I only have to oil the barrel arbor with d5 (hp1300) and install the barrel as is?
Third Question...
Is there any way you can tell if the ETA barrel complete is a cosc version, and do the watchmakers on this forum change the barrel on every service?
Lastly, this is just a little tip for, or another option to removing fix watch bezels without scratching or leaving marks on the case. This is usually done with a polished case knife, but will still leave a mark.
I use a painters mini plastic scraper.You can order the replacement plastic blades in different hardness ( I use the orange ones) and they will need to be replaced every time you remove a bezel.
This will only work on the fixed bezels that are held in place with a plastic gasket. It will not work on removing snapped on bezels.
I look forward to your replys- cheers

 

There is no really specific "hand bending tool" if that is what you are asking. I just use the same tweezers I use for handling and installing hands - "F" pattern tweezers from Horotec.

I normally add a small drop of HP1300 (not too many people use D5 anymore...unless they have some left over from a decade ago and never change their oils) where the arbor meets the barrel drum and cover. Also on the barrel arbor where it meets the plate and bridge of course.

Your supplier would know what version they are selling you, so you should be asking that. Note that there isn't really a COSC barrel - first the barrel doesn't change, just the mainspring. And the higher grade Nivaflex MN mainspring is used on both Top and COSC grade movements. There's no material differences between Top and COSC grades.

I don't change the barrel at every service, but I do change the mainspring at every service. If the barrel is in good shape there's no need to change it.

Cheers, Al

 

Thanks for your reply Al,
Just to confirm, do you apply the bend to the hand with your tweezers at the tip end, or gradually along the entire hand?
And is this before or after you have installed the hand?
As I am worried that if I apply the bend to the chrono seconds hand while it is installed it might bend the staff and not the hand.....or is the staff strong enough to not bend?
Cheers.

 

I do the bending at the tip of the hand, because that's usually where the bend is made at the factory. I also bend it when off the movement, with only small tweaks when it's installed as needed.

 

Hmm, interesting. I mostly deal with old movements, where replacing the blue steel springs is the norm, but I didn't know a mainspring change was recommended for watches of more recent vintage. Does Nivaflex lose its elasticity?

 

As I've written previously several times, it's standard practice in the industry. Sure there are watchmakers who cut corners on this, but brands do this all the time at service centers.

Even modern white alloy mainsprings, which were often called "unbreakable" when they first came out, still break. In addition mainsprings are often distorted when they are removed from the barrel, may have nicks, wear (in the form of a wavy pattern) or other defects. In the context of a full service that is costing a customer hundreds of dollars, changing the mainspring to ensure that it won't have any issues throughout the service interval makes sense.

The barrel is the engine of the watch, and again as I've said many times unless you are getting a smooth constant flow of power from it, the tweaking you do down the line will be largely moot.

Now if you are only servicing your own collection, so not selling those watches on as a business or servicing watches for others as a business, and you want to use the old springs and take the risk, that's up to you to decide. From a business perspective, replacing the spring makes good business sense. I don't think I've ever had a customer balk at the cost of a mainspring...

Cheers, Al

 

Removal, cleaning, rinsing, dying, lubricating, and re-installing an original mainspring is quite labor intensive, as opposed to simply fitting a new, factory lubricated mainspring right out of its retainer. No fuss, no muss, no bother. And “unbreakable” alloy mainsprings do break. It is false economy to re-use an original mainspring when servicing (for example) a Speedmaster. When a mainspring breaks in a chronograph movement, the whole movement generally requires dis-assembly, when replacing a mainspring. Older blued steel mainsprings are notorious for breaking when cleaned, rinsed, dried, lubed, and re-inserted. They don’t take well to that kind of disturbance. Constant flexing over decades of service causes them to “work harden”, and lose flexibility.