I recently purchased a Hamilton 996 mvmt from an eBay seller. It appears to run very well. I have the appropriate dial, hands and case to properly restore this watch.
One caveat in the seller's description. Sellers words here. It runs, and has been cleaned and inspected, finding all jewels and pivots in good condition but the hairspring collet is cracked. Collet should be replaced, though a tiny drop of superglue might hold it alright."
My question is that I have a 992 parts donor mvmt and I am wondering if the balance spring collet will work withe 996?
Thanks in advance for any help.

Michael

Michael,

The collet should be the same if you just swap it.

If you change the entire hairspring/collet from the 992 to the 996 it will likely require the watch to be re-timed as rarely do you find the strength of hairsprings to be the same. So weight will have to be carefully added or reduced to get the watch to time. Helps to have a timing machine, but can be done without just will take longer. Good luck with your project.

Rob
www.pocketwatchrepairs.net

As usual Mr Rob is full of good information.

The only 2 cents I will add is that hamilton made a large and small collet hairspring. So, if the balance staff in the 996 is a large collet and your donor movement has a small collet hairspring. Your desired results might not go as planned...

See picture below

Great point Jon!!!! On the 16 sizes I have found many more of the SC's used, but a visual check of the staff will tell you which you have.

Rob
www.pocketwatchrepairs.net

Any thoughts (from a manufacturing or cost view) why there would be a difference in the collet shoulder size on balance staffs - Rob?

Hamilton definitely improved their 16sz movement when they made the repair person friendly 992B

Hi Jon,

Hamilton did this a lot with their staffs making a LC and SC version. I am sure there are guys who can tell you exactly why they did this, but I am not really sure. I know I prefer working with the smaller collet's as it makes it easier to get the various punches down to the rivot for spreading and flattening out, but the LC are workable as well.

Yes, the friction staffs for the 992B's are designed and made so well it makes them one of the easiest staff jobs you will ever run into. As you say the entire watch is a pleasure to work on.

Rob
www.pocketwatchrepairs.net