These staffs were machined on (miniature) bar feed screw machines. Unfortunately we are not going to make them in 100,000/run quantities. I will put some of these into solidworks so that they can be dealt with more effectively by whatever means of manufacture makkes sense for "short runs". I will probably take them one at a time as I have the broken staff parts to measure and check.

I would start with a medium hard high carbon steel.

Hello Bulent,

It sounds as though your fine Schaublin CNC Machine is going a little beyond its tolerances of repeatability when it comes to the pivot diameter. It's amazing to me that it can actually "almost" do it! I believe the old staff making machines were very heavy, rigid affairs where the master setup "memory" for each staff type was provided by a cam which afforded great repeatability characteristics, but even so, I would imagine that the machined staffs were then put through a final finishing, polishing and verifying process.

I guess my message is this: If it is no problem to repeat the dimensions of the roller table, safety roller and hairspring collet tapers as well as the balance rivet, just leave the pivot ends over sized. Any watchmaker in possession of a basic lathe who is capable of changing a balance staff is certainly capable of reducing the pivot diameter. When I was doing watchmaking, I actually preferred a staff who's pivots were a little to big. For whatever it's worth, my method of reducing and polishing were as follows: For reducing, a small strip (about 3 x 15mm) of 2000 grit silicon carbide paper cemented to a flat piece of brass and lubricated with a little oil works very fast and leaves a very decent pre-finish. Just make sure you don't use your wife's best sewing scissors to cut the sandpaper or you could likely wake up dead with a crochet hook in the forehead! For a brilliant finish I used a round toothpick charged with a little watch oil (not your expensive Mobius but the cheap stuff) and 1/2 micron natural diamond powder. Quick and beautiful results every time!

If someone could supply obsolete or hard to find balance staffs, even with over sized pivots, It would be seen as a very valuable contribution to our trade.

Good luck in your efforts,

William

Hi William,

I am learning a lot of new thinks at this club. Thank you very much to you and to all.

Now I must go step by step. Actually I am waiting for small size special bar holders and special cutting tools. As material I will test A2 tool steel as Eddie informed me.

Finishing a staff pivot manually may be easy for you but not for others. This is a critical job. Do you have a picture of basic lathe?

I have a misting equipment manufacturing company. We are manufacturing misting nozzles in high quantity. We are opening orifices of these nozzles by a special EDM machine. (15 to 25 seconds) If the TORNOS MICRO 8 machine can open these orifices by micro drills, I will buy this machine.

Thank you again to everyone.
Bulent Ogel

I'll comment late as I've looked at doing this also.
I believe at least in the last 75 years, staffs were made on Swiss screw machines. These machines were cam machines and costly to setup. They are a lathe which has a support collect at the cutter(ie the main collet is farther back unlike a WW, turet or engine lathe). So, accuracy on small parts.

They are now cnc versions by Cicon's and other brands.
Material- by all the description and developments of steel, I believe these would have orginally been SAE 1065 or o-1 steel. About Rc=50 for maching- too soft and it will tear. I believe daniel's states heat-treat and temper blue. IT should bend about 30-45 degrees before breaking.

Case hardening could have been done as well as burnishing for finishing.
Big thing is you need RPM to get the surface feet per minute up to a decent clip. I'd guess cutting with small size Carbide or diamond cutters which are available.
The big massive machines is partly due to trying to get a consistent part in a factory situation. Vibration from the forklift, temperature variation etc can be bad. New airbearing lathe and mills run 50,000-160000 RPM spindle speed. Light feed with lots of speed and I've seen beatiful surface finishes on some hard to machine alloys. Medical industry uses some minature parts...

I've been working on this for about 6 months and have been working with a prototype/company right now.

M

PS don't forget the end of the pivot shape and 2 micron-surface finish.

Oh,
Best fit catalog says staffs are + or - 0.001 mm.
Your not trying to duplicate the method or materials used before- they did what worked best for high-volume production with materials/machines of their time. As long as you get a hard/smooth pivot and the dimensions correct.. it will work just fine.
If you use paramatization in CAD software, it could make it a snap to do any staff for cnc.
The machine I've looked at has a laser for measurment.. very very cool and fancy technology.

Michael,

Thank you very much for valuable informations.

no problem..

I looked through my old Carpenter tool steel catalog- maybe 0-1 steel Rc=55 would be my choice. A-2 might be a good try if you are going to post-heat treat. If not, it's mainly for thick sections where 0-1 won't work.
Rc=55 could be done with HSS, tungsten carbide or diamond. I'd be surprised if you can get a plung e cut on such a small diameter to work.
Let us know how it goes- I should have an price qoute on a 1857 #280 staff next week or so.
M

got another swift idea today..

How about hit the AWI library for a print on a hamilton staff- 992B for instance. Compare drawing tolerancing with "field samples".

Talked to some specialty guys today- over all length, surface finish of pivot and meauring step lengths of the various (roller table, balance, hair spring) are going to be hard to hit the length.
How critical do they need to be?
M

Michael are you asking me a question? I am sorry but I did not understood what you are asking.

Actually we are looking for different steels. At the and of this week all tool holders and tools will arrive.
Bulent

Found this old post on staff manufacture.
Just wondering if this service is still available.