Negus Chronometer Key Mystery

David D'Apice

Registered User
NAWCC Member
Mar 22, 2012
231
10
18
Country
Well, I can't say I've seen one of these before -- here's the key to my Negus Chronometer -- it looks as if it had a ratchet or pawl inside the lid, now, something's missing and they glued the whole thing together so there was no more ratchet action. I'm hoping somebody has an image of what the click looked like in this thing -- and I'm not even sure that the long flat clickspring was right. Any images would be of great help. The original cap to this has a pair of dolphins that are gilded -- quite lovely. If I can make a pawl, and locate two screws that are long missing, I can put the whole thing back together. Wish me luck. This is a new land to me --- hope everyone is staying safe and healthy. IMG_1570.jpg IMG_1571.jpg
 

gmorse

Registered User
NAWCC Member
Jan 7, 2011
11,837
1,810
113
Breamore, Hampshire, UK
Country
Region
Hi David,

Yes, this is a 'tipsy key', designed so that it's impossible to wind the instrument the wrong way, even if the operator 'has drink taken', hence the name!

It looks as though there should be a click in one post and its spring on the other; I suggest the click would be on the right-hand post and the spring on the left in your pictures.

Regards,

Graham
 

David D'Apice

Registered User
NAWCC Member
Mar 22, 2012
231
10
18
Country
Graham -- I've sketched something here --- let me know what you think. The little brass original spring is pretty fatigued -- I might consider making a new one. Not sure how to temper brass, but the click I'm drawing looks nice.

IMG_1572.jpg
 

Paul Regan

Registered User
NAWCC Member
Mar 4, 2003
712
75
28
Florida
Country
Region
I agree with Graham. Would love to see the rest of the key if possible and the chronometer as well.
Paul
 

gmorse

Registered User
NAWCC Member
Jan 7, 2011
11,837
1,810
113
Breamore, Hampshire, UK
Country
Region
Hi David,

I've sketched something here --- let me know what you think.
The click is just right, but the spring doesn't need to be brass, steel will be better, and also can be straighter, not bent under at the end.

Regards,

Graham
 

David D'Apice

Registered User
NAWCC Member
Mar 22, 2012
231
10
18
Country
Guys -- thanks for your input -- here's the key --- Graham, I believe the spring is shaped as it is because it can't interfere with the screw that holds the dolphins on --- I suppose if went around the outside of it.
IMG_1575.jpg IMG_1576.jpg
 

gmorse

Registered User
NAWCC Member
Jan 7, 2011
11,837
1,810
113
Breamore, Hampshire, UK
Country
Region
Hi David,

I believe the spring is shaped as it is because it can't interfere with the screw that holds the dolphins on --- I suppose if went around the outside of it.
Yes, like this, although it would be more elegant to cut the spring out of steel plate rather than bend a piece of old mainspring. The terminal curve needs to be shallow enough to allow the click to rise clear of the ratchet teeth, and the nose of the click has to clear the fixing screw when it's raised. The closer to the click pivot the spring bears on the click, the less the spring needs to be curved to allow the click to rise.

IMG_1572_edit.jpg

Regards,

Graham
 

David D'Apice

Registered User
NAWCC Member
Mar 22, 2012
231
10
18
Country
Graham - you are brilliant --- I'm wondering if they bent the original spring backward to create a pawl of its own -- and that failed --- probably after the original pawl was long gone. If I were to flatten the original spring, I bet it'd line up just like your drawing. This reminds me of the sort of spring one would find on one of those gun black powder flasks. In the illustration we've both created, I'm thinking that by turning the ratchet slightly clockwise, I could, in effect, shorten the length of the pawl.
 

gmorse

Registered User
NAWCC Member
Jan 7, 2011
11,837
1,810
113
Breamore, Hampshire, UK
Country
Region
Hi David,

Much the same considerations apply when making a new fusee click.

Regards,

Graham
 

David D'Apice

Registered User
NAWCC Member
Mar 22, 2012
231
10
18
Country
Seems like it was probably pretty thick piece of stock. I'm wishing I had a french click thick enough to start with, but I can certainly start from scratch with a jeweler's saw!
 

Paul Regan

Registered User
NAWCC Member
Mar 4, 2003
712
75
28
Florida
Country
Region
Thanks for showing the key David. Looks like Graham has you on the right track! For all the use that this is going to receive, you could make the click out of brass and the spring out of steel.

Anybody ever see a chronometer key like that? Quite fascinating.
Paul
 

Tom McIntyre

Technical Admin
Staff member
NAWCC Star Fellow
NAWCC Ruby Member
Sponsor
Aug 24, 2000
83,349
1,757
176
84
Boston
awco.org
Country
Region
Maybe with dolphins, it is a French chronometer. :)
 
  • Like
Reactions: David D'Apice

David D'Apice

Registered User
NAWCC Member
Mar 22, 2012
231
10
18
Country
Here's my latest prototype --- a work in progress ---- thanks to you guys -- I hear evidence of a ratchet sound, which is encouraging -- handmade from 1/8" steel. So far, so promising! IMG_1610.jpg
 
Our 2021 National Meeting in Hampton Roads Virginia
Topic related ad experiment
Know Your NAWCC Forums Rules!
RULES & GUIDELINES

Find member

Forum statistics

Threads
160,786
Messages
1,395,009
Members
82,835
Latest member
Rudjos
Encyclopedia Pages
1,099
Total wiki contributions
2,778
Last edit
Beat Setting 101 by Tom McIntyre