Jump to content

Hamilton 917 hairspring terminal curve?

Dawagner

By Dawagner
in Watch Repairs Help & Advice

 Share

Recommended Posts

Dawagner Member

Dawagner

Posted
Posted

Hey WRT,

Ive got a Hamilton 917 movement I am working on to get better at my hairspring techniques.  I was wondering if anyone had a link to a good copy of the terminal curve diagrams and knew what terminal curve these movements are supposed to have?  Pretty much the terminal curve is the only thing messed up on this piece and would like to try and fix it instead of replacing it.  Thanks!

Link to comment
Share on other sites
praezis Super WRT Addict

praezis

Posted
Posted

Hi,

the curve is determined by the ratio "distance of the regulator pins from center" to radius of the hairspring. Multiplied by 100 gives the curve number (eg 75) that you can look up in tables. If still needed, I can post one next week. 

Frank

Link to comment
Share on other sites
Orville New Member

Orville

Posted
Posted

Amazing answer by praezis above.  I never knew.  When I was super focused on hairspring manipulation as a learning module, I could figure out the termination by the sweep of the regulator and get it right most of the time. The important thing is that if it's not dead on, it's dead off.  Maintaining the coil of the spring is another key.  Distorted hairsprings don't work and I have a boxfull of them to prove it.  

Link to comment
Share on other sites
praezis Super WRT Addict

praezis

Posted
Posted

Just found one in an older post of mine.

There were different authors of overcoil diagrams with different design, but they all match the theoretical rules.
These are from Helwig, Glashutte.
You must size the picture so that the diameters match your vibrated hairspring. Length of the overcoil (from knee to regulator pins) is about 180° of outer coil.

Regards,

Frank

kurventafel_helwig_gl.jpg.b4cdf4d78fec52b6296895bbb02fa454.jpg

Link to comment
Share on other sites
Dawagner Member

Dawagner

Posted
  • Author
Posted

Perfect thank you sir, yes I am taking about a breguet overcoil.

Any tips you have for redoing one? The spring was fairly mangled and there was no good way to save what bends were in it so I have made it back to flat and concentric in preparation of redoing the terminal curve overcoil.

Thanks again!

Link to comment
Share on other sites
praezis Super WRT Addict

praezis

Posted
Posted

Hi,
Making an overcoil is one of the most challenging tasks in watchmaking.
I recommend finding a book that discusses this topic. Surely other members can help, as I know mainly German literature. 

Essential for bending are special curve tweezers with )) tips. New ones are no more made today, you can find them used or make your own. 

Frank
 

Link to comment
Share on other sites
 Share
Go to topic listing


  • Recently Browsing

    • No registered users viewing this page.

  • Topics

  • Posts

    • aac58
      Rare Seiko 5actus Watch??!! With a lot🤪🤔😲

      By aac58 · Posted

      This is not rare at all, the dial code and case code don't usually match.
    • Kkramme
      Coil for old Seiko Credor -- 4002920

      By Kkramme · Posted

      Good question!! Anyone know of a substitute movement??!! 🤔🙏
    • Kkramme
      Rare Seiko 5actus Watch??!! With a lot🤪🤔😲

      By Kkramme · Posted

      Interesting issue that I just noticed: this Seiko 5actus Watch from 1977 has a calibre listing on the dial of 7019-8030R but on the case back it says 7019-8010!! Like a mis-printed coin, is this watch therefore worth a lot of money for its rarity?? 🤪😲🤔🤪
    • Mercurial
      Smit

      By Mercurial · Posted

      I wish that was the case. The Aegler movements used in the early days by Wilsdorf & Davis (for brands like Rolex and Rolco) came in several sizes and without designated calibre numbers that survive.  They become a bit easier to identify during the 1920s. Below is an Aegler-Rebberg, 25.74mm in diameter. It’s from a woman’s Rolex wristwatch. Stamped Rebberg and 500 on the dial plate (but it isn’t a Rebberg 500, it’s the wrong size).  I’d be interested if anyone can identify the movement.  It is based off the Aegler Nr.1, circa 1903, but they based many many calibres of different sizes on it. The closest I have to a positive ID is the  ‘Rolex Nr.50’ circa 1917, but no dial side images or movement sizes are available in the references. There are identical looking movements in many sizes.  The 25.74mm of this movement is a particularly strange size for the era, it equates to 11.41 lignes.      Best Regards, Mark
    • GuyMontag
      FHF70 balance jewels settings

      By GuyMontag · Posted

      It looks like this movement comes with a number of different shock settings. Emmywatch shows that it comes in versions with no shock settings, 'Incabloc', 'shock resist', and 'Supershock'. Perhaps the different settings position the impulse jewel/roller table in a non-ideal position relative to the pallet fork/guard pin. Are you able to check under high magnification if the pallet fork and roller table are able to operate without any interference? Just for fun I took a look and I have one FHF 70 in my collection, a West End Secundus with a non-shock protected FHF70. I had a note with the watch that said, "Movement is stamped 'FHF 70', but the FHF70 looks to have sub-seconds instead of center seconds movement (??)" but that a google search turned up both types for this movement. EDIT: I just took a look in my parts drawer and I have a few of these movements, both in center seconds and sweep seconds, but they all are non-shock protected.  
×
×
  • Create New...