FHF 70 running slow, good amplitude

[Danh]

This one has me scratching my head, the watch (FHF70 movement) has been serviced recently, looks very clean also. It is running an amplitude of 280.

On maximum regulation adjustment, is measuring -500sec/day (according to the timegrapher) 

any Suggestions very welcome

thanks 

 

[matabog]

any extra-weight on the balance? Has the HS been changed?

One way to sort it would be to shorten the HS. Then dynamic poising!

[Nucejoe]

Additional candidates to be suspected are,  HS  not properly closed in by regulator pin.

If sweep seconds, is the seconds arbor bridged or held down by spring. Culprit with the bridged type.

 

 

[Danh]

Thanks guys - much appreciated - I will have a look

[Danh]

3 hours ago, matabog said:

any extra-weight on the balance? Has the HS been changed?

One way to sort it would be to shorten the HS. Then dynamic poising!

There is no extra weight on the balance, I don’t believe the HS has been changed - but will examine it all tonight

[Deggsie]

Additional candidates to be suspected are,  HS  not properly closed in by regulator pin.
If sweep seconds, is the seconds arbor bridged or held down by spring. Culprit with the bridged type.
 
 

Hello Nucejoe, could you explain this a bit more for me please. A photo of a simple had sketch would be great, if you have time. Thank you. Kind regards


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[Deggsie]

Hello Nucejoe, could you explain this a bit more for me please. A photo of a simple had sketch would be great, if you have time. Thank you. Kind regards


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It’s ok Joe, please don’t worry to reply. Reading again from the comfort of my armchair and not my workplace, this now makes complete sense to me and I understand it better now.
Kind regards. Deggsie


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[Nucejoe]

I was thinking how best to present my explanation, searched for some pix then thought there was a video by Mark on which this point can be shown as well as the video's subject. 

Most every brand produced their in house version of fhf70. Some got subsecond, some center second which comes in two different design. One holds the seconds arbor down in place to mesh with the min wheel, other uses a bridge to accomplish the same. In case you havn,t, as soon as you see a pic of these movements you see what I say. A picture is truely worth a thousand words and as a non native english speaker ten thousand of my words may barely do.

The regulator pin I think you have already figured out what I am talking about.

fhf70 is a jewel.  

Regards 

[Danh]

Currently working on it now, I am convinced someone has replaced the HS and it’s too long - see what happens later

[Danh]

Shortening the main spring has definitely solved the speed issue - thank you for that

just fine tuning the beat error now 

thank you for the inspiration 

[matabog]

the HS, u mean

[Nucejoe]

Shortening the hairspring dose increase frequency, the problem however is, if the fault is somewhere else, you havn,t cured rather just a relief, if unsure I avoid cutting the extra length off of HS.

Regards

[matabog]

How is the amplitude? And the positional error.

 

If those are fine, you nailed it!

[Danh]

7 hours ago, matabog said:

the HS, u mean

Haha - yes

[Danh]

1 hour ago, matabog said:

How is the amplitude? And the positional error.

 

If those are fine, you nailed it!

They are good thanks, amplitude at 290 and the PE is less than 1.0 now

fiddly job but learnt a lot (especially patience lol )

[Danh]

1 hour ago, Nucejoe said:

Shortening the hairspring dose increase frequency, the problem however is, if the fault is somewhere else, you havn,t cured rather just a relief, if unsure I avoid cutting the extra length off of HS.

Regards

I agree - it’s the first time I have come across an issue like this, in this instance I do not believe there was an issue elsewhere, all else seemed good

[matabog]

Could you tell us a bit more about the repining you did? Was there a boot-leg to be redone? 

I mean in theory is so simple, but practice kill us all...

Some pictures would be much appreciated!

[Danh]

1 minute ago, matabog said:

Could you tell us a bit more about the repining you did? Was there a boot-leg to be redone? 

I mean in theory is so simple, but practice kill us all...

Some pictures would be much appreciated!

I have not taken pictures - sorry normally I do but this job required 120% concentration and a lot of lateral thinking

the very small pin was very difficult to remove that was holding the HS end in place. Eventually I got it moving and out, but it was not very tapered.

i ended up taking ages to reshape it slightly with 2000 grit paper.

it turned out it was easier to cut the HS and remove the  pin then.

obviously I had to estimate the bend to put back into the spring, and then shape it again slightly when back in situ and pinned.

the pin was fiddly as hell to get back into place, thank god for No5 tweezers.

then checked the shape of the spring again and tweak accordingly 

I ended up refitting the balance complete and moving the adjuster to give me a visual line for working out the orientation of the pallet jewel, taking it off and turning the collet until I was happy, did that a couple of times.

overall about 4 hours 

[Nucejoe]

38 minutes ago, Danh said:

I agree - it’s the first time I have come across an issue like this, in this instance I do not believe there was an issue elsewhere, all else seemed good

Lucky you got the right HS length on the first try, good reading on timegrapher. Congrat

 

[Danh]

5 minutes ago, Nucejoe said:

Lucky you got the right HS length on the first try, good reading on timegrapher. Congrat

 

That was a judgement call with how close I could get to a good timing and how much travel I reckoned I needed 

many shorter than the guess by a couple of mm I would have had to lengthen it back a bit with the extra length

[rodabod]

Top skills, Dan. Well done.