Sourcing hairspring

[dadistic]

Out of curiosity I was going to order some nispan c springs from britishprecisionsprings.co.uk, the price looked reasonable. Then I found out that shipping to U.S. would be over 30$, and I got un-curious very quickly

 

Edited October 2, 2021 by dadistic

[Nucejoe]

Perhaps we are mistaking weight and force.

Dyne is a unit of force, it remains the same regardless of location, its constant no matter where in the universe you measure it.

The weight of any massive body  is zero in space ( absence of gravitation field) .

 

 

 

 

 

[dadistic]

11 hours ago, praezis said:

 

What the hell is this CGS now?
In short: it is the needed torque to turn a hairspring by 57 deg (57deg equals rad=1) when it has a diameter of 1 cm. 
Its unit is "dyn * cm^3"

Frank

I'm still trying to understand this. I think I've got the general concept,  but I am confused  by the unit. Force times centimeter cubed? It sounds like the torsion spring constant,  but that is newton-meters/radian.

Do you have a reference for this definition? It sometimes helps me to read more than one explanation.

Thanks!

[dadistic]

Ok, I've found some other definitions - 

"What is the C.G.S. number of a hairspring? This is a number indicating the "strength" of a given diameter. To be more exact, it indicates the "elastic moment" of a hairspring at a diameter of one centimeter when the spring is deflected by a one-half centimeter long arc of a circle. (The "elastic moment," incidentally, equals the force the spring exerts, expressed in grams, multiplied by the radius, which is one-half of a centimeter. )

Horological Times January/1989
Article printed by special permission of the Associated Spring Corp. and F.N. Manross and Sons"

Since a one-half centimeter arc of a one centimeter diameter circle is one radian, we are close to your definition, but not the same.

Another one - 

"The spring number indicates the restoring couple of the spring when its diameter is one centimetre"

And I found this to define restoring couple - 

"The moment (or torque) of a couple is calculated by multiplying the size of one of the force (F) by the perpendicular distance between the two forces (s)."

Aargh!

 

[jdm]

14 hours ago, dadistic said:

 Then I found out that shipping to U.S. would be over 30$, and I got un-curious very quickly 

That is likely because they want to ship courier, as some think is better than Post. But in my experience of hundreds both tracked and untracked shipments, Post services are just fine, only the latter is a bit unpredictable in transit times. See if you can convince them by releasing all responsibilities.

[jdm]

11 hours ago, dadistic said:

I am confused  by the unit. Force times centimeter cubed? 

I think that Praezis mistyped the definition of force in the CGS system, which is the following:

dyn = g * cm/s^2

Again, the reference article: https://en.wikipedia.org/wiki/Centimetre–gram–second_system_of_units

In all systems, when there are seconds cubed, it's about power, not force, nor torque.

 

[clockboy]

13 minutes ago, jdm said:

I think that Praezis mistyped the definition of force in the CGS system, which is the following:

dyn = g * cm/s^2

Again, the reference article: https://en.m.wikipedia.org/wiki/Centimetre–gram–second_system_of_units

In all systems, when there are seconds cubed, it's about power, not force, nor torque.

 

Thanks JDM it’s still difficult to decide the hairspring to purchase, for me anyway. Measuring the strength of an existing spring is also difficult to determine. Unless the ligne of a watch is always the determining factor. The drop test is a guide ie attach the new spring to the balance and it should dangle by approx 1/2” I have used this method and it is close ish. When time I must practice pinning up a H/S to a collet which will open up so much more opportunities when looking for a replacement. 

[Nucejoe]

  Thank you all sharring your knowlege, I certainly learned and special thanks to dadistic who shed light on how to go about determining  what CGS I need. 

I must apologize for loosely speaking of kgf in my post, Frank is right the unit of force in CGS system is dyne. I was borrowing the term kgf from the conversion rate to newton, one kgf=9.807 N , the figure 9.807 comes from the gravitational constant ,the pull earth exerts on massive bodies. so sorry sorry. 

I hope Frank finds sometime to furthure shed light on how to come up with this CGS thing, so I can start fixing the rest of my watches.

Stay safe.

Regs 

 

 

 

 

 

[jdm]

13 hours ago, Nucejoe said:

the unit of force in CGS system is dyne.

Correct. Now, let's recall the definition of force in all units systems:

the force that would give a free mass of one gram an acceleration of one centimetre per second per second.

Since you guys may be bored with Wikipedia, I'll give a difference source this time: https://www.britannica.com/science/dyne

Now, as I mentioned before, there is a time component in the physic's definition of force, but when it comes to measuring the strength of an hairspring, or even a mainspring, time (or acceleration) is not practically involved. That is because we're dealing with largely elastic objects, for which, in the end, we're looking to find the  https://en.wikipedia.org/wiki/Elastic_modulus

 

Quote

how to come up with this CGS thing

Well, those did come up with the "CGS thing" is the hairspring industry, when they switched from the "ancien" (means old in French) still present the table posted by dadaistic, to a coherent system of units, like CGS.
You can calculate the "strength" - aka elastic modules of a torsion spring, or you can measure it on an actual object, and they should be reasonably close.
And if you need to convert to the "British company" units, again I believe the simple proportion is: 1 / 57 = x / 100, that is multiply any "CGS value" by 1.75. If I'm saying something incorrect, my apologies and I'll be happy to learn better.

 

Quote

I can start fixing the rest of my watches.

I think we can discuss units and force until blue in the face but that will not make any hairspring to appear on your bench. So as mentioned above one would need to order a range which likely cover the application, and start from there. It would be crazy to make right away a large order of a single type and expect to be correct.

[praezis]

Hello,
for me it is a bit painful to find the right english word for the technical terms used here.

CGS numbers were invented by 'the hairspring industry' (in fact profs Guillaume and Donat) to overcome old arbitrary classifications like 'strength number' and 'size number' to get hairsprings calculable in the CGS (the units) system. That helped to quickly and exactly determine a needed spring instead of 'trying' a spring.  

CGS number is a parameter, not a torque dimensional. To get the torque*, you have to divide the CGS number by the squared diameter of the hairspring. 

* you get the 'deflecting force' D, eqivalent to the 'spring constant' of linear springs. Torque M = D * angle(rad). D is the torque @ 57deg deflection.

If you alter the length/diameter of a given hairspring, you will also alter its 'D' - so it is not appropriate to generally specify a hairspring. CGS number is however.

The formula to find the right hairspring was posted by dadistic already. However you need to have one hairspring with any known CGS number. 
Tables help to come into the ballpark, but are not determined enough.
Don't know if Joe wants to go that route, but I compressed the procedure in the attached pdf.

If you calculated the correct CGS #, next imho bigger issue is to find such spring. The British comp. may have it, but is not helpful finding it, their 'Torque' data are unclear. In contrast to me, jdm found their information sufficient, maybe he can help you. 
But factor 1.75 cannot be right, you were still off by some decimals compared to an expected CGS #.

Frank

CGS_INFOe.pdf

Edited October 4, 2021 by praezis

[nickelsilver]

I would imagine the British Springs folks can give a conversion from their numbers to CGS. I assumed their numbers were CGS, and who knows, maybe they are but they call it something misleading? As a manufacturer they must know the difference and can tell you.

[praezis]

30 minutes ago, nickelsilver said:

As a manufacturer they must know the difference and can tell you.

Exactly!

On 10/1/2021 at 5:12 PM, praezis said:

Some time ago I asked them for a method to convert to CGS, but no reply.

Having read their homepage, I suspect this company just sells inherited stock and all specialist with the needed knowledge retired long ago.

Frank

[Nucejoe]

45 minutes ago, praezis said:

CGS number is a parameter, not a torque dimensional. To get the torque*, you have to divide the CGS number by the squared diameter of the hairspring. 

So CGS is proportional to torque per unit are of the coil.  Spring's thickness is conveniently disregarded here, then I may get the right beat from spring of different thickness, but not dynamic stability of oscilator. 

 

 

[Nucejoe]

13 minutes ago, Nucejoe said:

So CGS is proportional to torque per unit are of the coil.  Spring's thickness is conveniently disregarded here, then I may get the right beat from spring of different thickness, but not dynamic stability of oscilator. 

 

 

Correction .  torque per unit area of the coil.

[praezis]

5 minutes ago, Nucejoe said:

Correction .  torque per unit area of the coil.

torque multiplied by unit area of the coil?

[Nucejoe]

Just now, praezis said:

torque multiplied by unit area of the coil?

Right ,    Proportional !    either directly or inversly.

Thickness and strength paly crucial role in oscilators  stability on wrist.

We can disregard them for desk and wall clocks. 

[jdm]

3 hours ago, praezis said:

But factor 1.75 cannot be right, you were still off by some decimals compared to an expected CGS #.

Thank you for pointing out my mistake, due to superficiality. I went to look to the "stock springs list" by the British company more closely.

First thing that one can notice is that the O.D. starts at 6mm, which could be right for a 12mm balance wheel, something like a 13"" mov.t! Based on that only, I suppose these are not wristwatch, and possibly not even clock hairspring. Rather, have been made for a variety of other devices, like speedometers, detonation timers, pressure meters, just like their home page says.

Then looking at the quoted Torque for a same O.D. we see that it varies largely, even about 200 times for 7mm O.D. springs. Unlike what we learn from the old tables, that the CGS# is very related to the balance diameter. 

Another clue is the "custom springs" pages, the parameters on "how to choose a material" are not like anything related to watchmaking.

Despite the oscillator instrument in the tiny picture on the home page, nothing says or suggest that these are in fact, horological hairsprings.

Conclusion, IMHO it is safe to disregars this source for watch repair needs. I apologize for any confusion I may have caused when trying to compare oranges to apples.

[dadistic]

3 hours ago, praezis said:

 

CGS numbers were invented by 'the hairspring industry' (in fact profs Guillaume and Donat) to overcome old arbitrary classifications like 'strength number' and 'size number' to get hairsprings calculable in the CGS (the units) system. That helped to quickly and exactly determine a needed spring instead of 'trying' a spring.  

CGS number is a parameter, not a torque dimensional. To get the torque*, you have to divide the CGS number by the squared diameter of the hairspring. 

 

 

I'm attaching a couple of articles by Andre Donat describing the hairspring numbering system, these are from the 1930's .

Unfortunately for me, they are in French, of which I have none, so I am working on a (machine) translation.

They numbering paper was retrieved from here -

http://articles.adsabs.harvard.edu/full/seri/AFChr/0004//0000254.000.html

And the other one from the same place, but I've misplaced the link. 

When I have a usable translation I'll post it in a new thread.

 

 

 

1934AFChr___4__297D.pdf 1934AFChr___4__233D.pdf

[praezis]

@dadistic
Thank you for the found docs! I really hope you manage a translation, I have the same language issue as you

19 hours ago, jdm said:

First thing that one can notice is that the O.D. starts at 6mm, which could be right for a 12mm balance wheel, something like a 13"" mov.t! Based on that only, I suppose these are not wristwatch, and possibly not even clock hairspring. Rather, have been made for a variety of other devices, like speedometers, detonation timers, pressure meters, just like their home page says.

Totally agreed. Most springs were made from bronze alloy, those can be used for alarm clocks at best.

But sometimes you may need a hairspring for extra big watches with CGS >>30 that maybe found on that site.
So I tried a conversion from their 'Torque' to CGS. Ignoring the slashes as mathem. signs:

From their table: Torque M [gm * cm]
-> D = M * 57.3 /100 [gm * cm]
-> CGS' = D * diam ^2 [gm * cm^3] 
-> CGS = CGS' * 981 [dyn * cm^3] 

CGS = Table value 'Torque' * 562 * diameter * diameter

Then the 2nd spring #3897 will have a CGS of 0.00169 * 562 * 0.6^2 = 0.342
Could fit a 10''' watch. Doesn't sound too bad.

A last word re units:
What you call 'gram force' is 'pond' in my country. But this unit of force was abandoned and replaced by 'Newton' about 50 years ago! I supposed this happened all over the world then in physics and engineering. Didn't that happen in US/UK, too?
Then the British table can hint at how old it really is.

Frank 

[jdm]

43 minutes ago, praezis said:

What you call 'gram force' is 'pond' in my country. But this unit of force was abandoned and replaced by 'Newton' about 50 years ago!

Your continental Europe country has been metric since the beginning or almost. Within metric systems, all coherent systems are directly convertible, just add or remove zeroes. CGS is great for small number, MTS for big ones, SI maybe tried to be compromise, fact is, each industry or science adopts whatever scale or unit is more convenient, but there is no confusion or disaster happening, also because we are taught to do metric equivalences at age 8 or so.

 

43 minutes ago, praezis said:

I supposed this happened all over the world then in physics and engineering. Didn't that happen in US/UK, too?

No it did not. The US uses English units in all industries and households needs, they are the only one left with Liberia and Myanmar. Of course, when it comes to science, (or rocket science where they have been burned in the past  https://www.wired.com/2010/11/1110mars-climate-observer-report/) they use metric, they did also for Apollo missions, but this detail was never passed to the public, as it would have seemed bizarre or antipatriotic.

The UK is more interesting as it's clearly divided in Imperial diehards, and metric adopters. I know of two reputable resellers of hobby machining products, one has 75% of his offering in Imperial sizes, and the other the other way around, revealing fact, the latter has "Euro" in the name!
The current UK  gov.t is also pushing in the anti-metric direction because they say that people doesn't know how much a pound of apples cost. 

 

 

[praezis]

Thank you for that insight, jdm. It explains a few misunderstandings in this thread.

Frank

[dadistic]

The situation with units in the US is a constant source of consternation for me. I try and work with metric units whenever I can, but the manufacturing company I've worked at for 30 years is all US customary units (inch, etc.). Not even the same as the Imperial units. 

We have the ridiculous situation where we buy soda in 2 liter plastic bottles, but milk comes in 1 gallon plastic jugs.

Very silly, but no one seems to care.

Cheers

[dadistic]

5 hours ago, praezis said:

@dadistic
Thank you for the found docs! I really hope you manage a translation, I have the same language issue as you

Frank 

My first attempt at a translation is here -

 

[JohnR725]

On 10/2/2021 at 12:51 PM, Nucejoe said:

You are right, I have been on the quest to source some hairsprings as I have several hundered calender pointers awaiting good hairspring. Hairsprings are the first part to get ruined during service/ repair and challanging to sort out, so vibrating with new springs is the prefered option at my age.

several years ago in one of the BHI magazines they had a nice article it explains the problem. At one time you could buy packets a CGS hairsprings which is why they show up on eBay now. But that's no longer available they no longer make hairsprings by CGS and put them in packages.

The Swiss who like to rearrange things for better manufacturing or get absorbed by Swatch group then like to do really clever things like? Like why make CGS hairsprings to vibrate when you can make the exact hairspring for the watch manufacturer. Or if the watch manufacturer doesn't want to vibrate their own spring the company will do that for them. There's no longer any need to manufacture generic CGS Springs and have them sitting around in the warehouse waiting for someone the request them like us.

but maybe the BHI article is wrong maybe they are still available may be can ask the manufacture like this one.

https://www.nivarox.com/

On 10/2/2021 at 9:48 AM, clockboy said:

Also I do not understand their sizing system.Also those that do come with a collet take for ever to be delivered. The last time I used them it was three months and that was after several nagging emails from myself. 
 

http://www.britishprecisionsprings.co.uk/html/stock_spring_list.html

I do notice on the website they do custom hairsprings so maybe that would be the route you want to go. But based on the description of their prompt service I have to wonder if custom might mean you might have to physically be there to pound on their door to make sure they actually will get it done in your life time. sometimes I wonder if businesses like this are either swamped with orders or perhaps they are hobby businesses something that somebody's doing on the side.

 

 

 

[Nucejoe]

 I contacted the Atlasmicrotech.ch that Nickelsilver provided the link to. Apparently the manufacturer considers making hairsprings to individual customers. I guess depending on quantity of the order, My 500 to 1000 piece order will do.

Here is the inquiry forum in French or Swiss French, I am suppose to fill out. I don't understand French and so far haven't been able to get it machine translated. Seems its asking some tech specifications, Including CGS No.

Will follow up with this and keep you all posted.  

Wouldn't it be useful to start a 405 club on WRT to order parts members need? at fraction of retailers price? 

 

FICHE CONTACT CLIENT

 

 

 

Nom de la société : …………………………..

Adresse : ……………………………………..

                ……………………………………..

Tél : …………………………………………..

Fax : ………………………………………….

 

Personne de contact : …………………………

Tél direct : ……………………………………

E-mail : ………………………………………

 

 

 

SPECIFICATIONS CLIENT

 

Type de spiral : plat          cylindrique        sphérique 

 

Inertie du balancier : ………………..g.cm2

Fréquence : ………………………...… Hz

Rayon de la virole : ……………….… mm

Diamètre extérieur du spiral : ……….. mm

Hauteur du spiral : …………………... mm (si spiral de forme))

N°CGS : …………………….

 

Regs

Joe