Beat rate - balance or hairspring

[canthus]

What determines the beat rate the balance or the hairspring. 

I have a movement (CattinC64C) which had a damaged h/s which I couln't sort, so I ordered a new balance complete.  The movement now runs very fast (even when regulator is set at max -) and the timegrapher picks a beat rate of 19800 whereas the old balance showed 18000 so I guess this why it runs very fast..  If its the balance that determines the rate could I try using the h/s from the new balance on the old balance wheel?  Only a cheap movement so I don't want to spend any more money on it.

[JohnR725]

Occasionally the timing machine gets confused when it's in the auto mode. So you need to set the machine to 18,000 and then see what happens. Then on not familiar with the company is this a pin lever watch? That conceivably might confuse the timing machine.

Picture would be nice the balance wheel with hairspring so we can see if it looks right.

Then there are some watches that actually came in different frequencies and I can't remember how the part number changed it might just been a letter but it would depend on the manufacture. So it's possible that you do have a 19,800 bph balance wheel. The other thing is if you put the hands on what are they doing are they running really fast?

Then both the balance wheel with its hairspring determine the frequency. Usually the hairspring is vibrated to a specific balance wheel. You can change the balance wheel characteristics like adding or removing weight but it usually has a minimal effect versus a different hairspring.

[khunter]

The train of wheels determines the actual beat rate, the balance wheel and hairspring regulate it. The old "coarse train" watches had fewer leaves on the escape wheel pinion and the corresponding 4th wheel, and ran at 14400bph. Then along came fine trains at 18000, and then beyond that 19800, 21200, etc....one thing that remains constant is the rotation of the 4th wheel, which is one revolution in one minute. If the beat is 18000, the escape wheel advances 5 teeth per second (3 in and 2 out),  with 15 teeth on the escape wheel itself, so a complete revolution every 3 seconds. This translates into a 20:1 gear ratio between the escape wheel and the 4th wheel, so if the escape wheel has 8 leaves, the 4th wheel needs 160 corresponding teeth. 19800, with the same configuration, would be 5.5 teeth on the escape wheel, not possible, so the leaves and teeth were increased (not sure of the exact numbers) to slow down the advancement of the 4th wheel to maintain one revolution per minute. 

The hairspring is selected for each balance, and vibrated (length determined) to give the proper rate of 18000, 19800, or whatever. The screws make a HUGE difference as in hours a day if removed or added. The lighter the wheel the faster it spins, and of course heavier is slower. The screws are there for poise (balance), and in the case of split rim balances also temperature compensation. The screws should not be removed or changed in position unless you really want to mess with the compensation and poise. If it took more/heavier screws to bring a balance into proper poise and compensation, then a stronger hairspring was used to control the added weight.

Edited March 4, 2018 by khunter

[canthus]

Thanks guys for the responses.  It is a pin-lever movement with Roskopf canon on barrel, but I don,t have any suitable pics.  The original h/s was not flat and my attempts to sort basically ruined it, hence the new balance complete route!  The spec sheet indicates 18000 but the watch gains minutes a day when fully assembled with hands fitted, which seems to tally with timegrapher indicating 19800.  Checked everything and de-magnetised.  Balance wheel is a solid wheel without screws.  I had put it aside, but thought I would ask the questions anyway.  Will perhaps have another try later and maybe keep eye open for cheap used movement.

Edited March 5, 2018 by canthus

[khunter]

Is there perhaps some extra hairspring extending past the stud? If so you could try re-pinning it making it a bit longer. Otherwise with a solid balance there's not much adjustment possible. 

[Deggsie]

Is there perhaps some extra hairspring extending past the stud? If so you could try re-pinning it making it a bit longer. Otherwise with a solid balance there's not much adjustment possible. 

I’m following with interest as I have recently asked a similar question regarding an AS2063 which gained much more even with regulator on maximum negative setting.
No HS damage and gear train seemed original. Only problem is the owner never saw it previously running to confirm it was a good watch.


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[JohnR725]

For the AS 2063 It's a modern watch with the floating regulator. Conventional regulators with arms have limited range of regulation. Floating regulators have a much much bigger range of regulation if it goes beyond that you have something else going on is not a regulation problem. So then you have to look at the usual suspects which on a modern screwless balance wheel is something is wrong with the hairspring. Now what I mean by wrong I don't mean that it's been swamped it's always possible somebody swapped a hairspring in which case you're totally screwed and nothing can be done. So the usual hairspring problems are they hairspring isn't where it's supposed to be. In other words it's bumping into something it's rubbing on something the coils are stuck together. This is where you have to visually really lock and sometimes it's hard to see. This is where it becomes really nice to have a timing machine or the software that lets your computer be the timing machine. Because without that there are things that you may or may not be able to see but timing machine will give you a clue. It's also nice if you can listen to the watch amplification is nice. If they hairspring is bumping into something it makes a nice musical sound for instance.

 

[Deggsie]

For the AS 2063 It's a modern watch with the floating regulator. Conventional regulators with arms have limited range of regulation. Floating regulators have a much much bigger range of regulation if it goes beyond that you have something else going on is not a regulation problem. So then you have to look at the usual suspects which on a modern screwless balance wheel is something is wrong with the hairspring. Now what I mean by wrong I don't mean that it's been swamped it's always possible somebody swapped a hairspring in which case you're totally screwed and nothing can be done. So the usual hairspring problems are they hairspring isn't where it's supposed to be. In other words it's bumping into something it's rubbing on something the coils are stuck together. This is where you have to visually really lock and sometimes it's hard to see. This is where it becomes really nice to have a timing machine or the software that lets your computer be the timing machine. Because without that there are things that you may or may not be able to see but timing machine will give you a clue. It's also nice if you can listen to the watch amplification is nice. If they hairspring is bumping into something it makes a nice musical sound for instance.
 

Apologies for the delay in replying. I only just noticed this. I appreciate your time to reply and beginning to realise I definitely need a timegrapher. Converse to the as2063 problem I had (was running fast but not resolved) I also have an old Newmark which I just cannot get to run fast enough. Your comment about the spring swap has me thinking........

I may need t slightly shorten the spring and as a consequence adjust the beat

Thanks for the food for thought

Regards Deggsie


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[rappeleur]

Funny, I had quite that same issue the other day: See my recent thread...