• Important Executive Director Announcement from the NAWCC

    The NAWCC Board of Directors is pleased to announce that Mr. Rory McEvoy has been named Executive Director of the NAWCC. Rory is an internationally renowned horological scholar and comes to the NAWCC with strong credentials that solidly align with our education, fundraising, and membership growth objectives. He has a postgraduate degree in the conservation and restoration of antique clocks from West Dean College, and throughout his career, he has had the opportunity to handle some of the world’s most important horological artifacts, including longitude timekeepers by Harrison, Kendall, and Mudge.

    Rory formerly worked as Curator of Horology at the Royal Observatory, Greenwich, where his role included day-to-day management of research and digitization projects, writing, public speaking, conservation, convening conferences, exhibition work, and development of acquisition/disposal and collection care policies. In addition, he has worked as a horological specialist at Bonhams in London, where he cataloged and handled many rare timepieces and built important relationships with collectors, buyers, and sellers. Most recently, Rory has used his talents to share his love of horology at the university level by teaching horological theory, history, and the practical repair and making of clocks and watches at Birmingham City University.

    Rory is a British citizen and currently resides in the UK. Pre-COVID-19, Rory and his wife, Kaai, visited HQ in Columbia, Pennsylvania, where they met with staff, spent time in the Museum and Library & Research Center, and toured the area. Rory and Kaai will be relocating to the area as soon as the immigration challenges and travel restrictions due to COVID-19 permit.

    Some of you may already be familiar with Rory as he is also a well-known author and lecturer. His recent publications include the book Harrison Decoded: Towards a Perfect Pendulum Clock, which he edited with Jonathan Betts, and the article “George Graham and the Orrery” in the journal Nuncius.

    Until Rory’s relocation to the United States is complete, he will be working closely with an on-boarding team assembled by the NAWCC Board of Directors to introduce him to the opportunities and challenges before us and to ensure a smooth transition. Rory will be participating in strategic and financial planning immediately, which will allow him to hit the ground running when he arrives in Columbia

    You can read more about Rory McEvoy and this exciting announcement in the upcoming March/April issue of the Watch & Clock Bulletin.

    Please join the entire Board and staff in welcoming Rory to the NAWCC community.

Poised Collets and Gibri's balance spring weights

D.th.munroe

Registered User
Feb 15, 2018
804
275
63
39
BC Canada
Country
Region
I've had some of these questions for years, but my mind has been wandering while working lately (not alot of challenging stuff).
One question was about Hamiltons use of poised balance spring collets to get closer positional rates, and why it didn't seem to be adopted more? Was it not enough of an improvement? And what watches used them?

I was also thinking about Gibri using weights on the spring itself and from his description of where they were put, it seemed to me that the weights were possibly balancing out the poise of the collet achieving close the same result.
I wonder if Gibri had thought of poising the collet, he may have done that instead of the weights?

Gibri's book was one of my first watchmaking manuals, for anyone else who wants to read the whole book.

Dan
 
  • Like
Reactions: Paul_S

DeweyC

NAWCC Member
Feb 5, 2007
2,338
912
113
Baltimore
www.historictimekeepers.com
Country
Dan,

Thank you for that link. He really laid the foundations of modern watch theory but does not seem to get much credit. A lot of companies dropped posied pallets shortly after his analysis of poising vs increased mass (momentum) was published. I think I remember reading it and IIRC it is the complete version of the series he did for one of the 19th cent horological journals ( I have the series on a HD I cannot access).

Poising at the collet. Wasn't that a mid century thing? I think Elgin used it wrist watches?

I have to read the treatise and think how it all fits with what I think I know about adjusting. My books are in storage, but did Jendritski mention it?

Thanks for the puzzle.
 
  • Like
Reactions: D.th.munroe

DeweyC

NAWCC Member
Feb 5, 2007
2,338
912
113
Baltimore
www.historictimekeepers.com
Country
Yes, that is the complete series from Jewelers Circular Keystone. I use that book as a reference for discussions regarding watch theory.

Are you wondering how poised collets would fit in with his analysis?

I do know the effect of mass distribution increases as the distance from the axis. So small changes to the poise at the collet would have a small impact compared to the distribution of mass at the rim. I wonder if the impact was even measurable?

Besides, we concentrate our efforts on timing on the distribution of mass on the rim. Which would seem to swamp any benefit of poising at the collet.

I know Hamilton made a big deal about this on the M22 but I wonder now if it was just marketing for the benefit of the USN. After all, these were kept dial up unless something went seriously wrong.

I know Hamilton played these games. When I purchased my 500 M21s from the USN in the 1990s, I copied all the production cards for them at the NAWCC. Almost all of them had "bruised pivots" which needed to be corrected. What in the world is a bruised pivot:???: and if there were so many, why not correct the issues around handling that caused it! There were other comments that were repeated word for word but I cannot recall them. Bruised pivots stuck in my mind.
 

D.th.munroe

Registered User
Feb 15, 2018
804
275
63
39
BC Canada
Country
Region
I was thinking basically the same about the (oh I should've said "counterpoised") collet, wouldn't it just have been so small that a couple degrees, if that, turn of a screw would've countered the effect.

This is where I read about Hamilton using them. More info than I remember. 1946 HIA Journal Archives page 28 of September and page 9 of October 1946
Dan
 

D.th.munroe

Registered User
Feb 15, 2018
804
275
63
39
BC Canada
Country
Region
And thank you Dewey, I know you know more about timing than I do.
It was your mention and praise of him a few years ago reminded me I had that book and made me reread it.
I don't remember if Jendritski mentioned either, I dont own his books yet, I have read them but not in many years.

I was more thinking about if Gibri's weights were actually indirectly compensating for lack of poise of the collet or if it was about the weight of the spring itself.
Dan
 

DeweyC

NAWCC Member
Feb 5, 2007
2,338
912
113
Baltimore
www.historictimekeepers.com
Country
And thank you Dewey, I know you know more about timing than I do.
It was your mention and praise of him a few years ago reminded me I had that book and made me reread it.
I don't remember if Jendritski mentioned either, I dont own his books yet, I have read them but not in many years.

I was more thinking about if Gibri's weights were actually indirectly compensating for lack of poise of the collet or if it was about the weight of the spring itself.
Dan

Dan,

You just brought this to mind. Somewheres (Jendritski:???:) there is a photomicrograph of a balance spring with mass added to the spring near the collet. I forget the purported purpose. But I think it was related to your question.
 

D.th.munroe

Registered User
Feb 15, 2018
804
275
63
39
BC Canada
Country
Region
I'm guessing it may have, starting on page 79 of the above Gibri book, he talks about his reasoning and experiments (I should've pointed this out earlier as well oops)
 
Know Your NAWCC Forums Rules!
RULES & GUIDELINES

Find member

Staff online

Forum statistics

Threads
163,531
Messages
1,421,010
Members
84,930
Latest member
Carolina2004
Encyclopedia Pages
1,101
Total wiki contributions
2,857
Last edit
Aurora's 15 Ruby Jewel Movements by Greg Frauenhoff

514 Poplar Street
Columbia, PA 17512

Phone: 717-684-8261

Contact the Webmaster for perceived copyright infringement (DMCA Registration Number 1010287).

Copyright © National Association of Watch and Clock Collectors Inc (A 501c3 non-profit corporation). All Rights Reserved.

The NAWCC is dedicated to providing association services, promoting interest in and encouraging the collecting of clocks and watches including disseminating knowledge of the same.