Gruen 415 - Erratic Timegraph after Service/Balance Replacement

[SAK335]

I have this Gruen 415 that I got as a non-runner.  I did a service after seeing no real issues and unfortunately, when reassembling the balance after lubricating the cap jewel (this is not shock protected and you have to pull the balance to undo the screws to release the jewel), I dropped the balance and twisted the hairspring pretty badly.  I found a replacement and installed it, and it fired right up, but it's running quite slow as you can see in the photos.  Even when I max out the adjustment it is still roughly 100 sec/day slow.  Beat error is OK once the adjustment arm is maxed but climbs as you move the adjustment arm to the middle of the range.  Amplitude is OK, maybe a bit low.

I've messed with the hairspring a bit to try to get it correct.  I removed the spring and put a slight bend near the regulating arm and that helped a bit.   Originally it was bunched to one side and I found that I had also bent the regulating pin slightly when putting it back together.  Once that was straightened out, it ran better but the hairspring was not (and still isn't) "breathing" the way it should.  Basically the spring looks great towards the bottom of the balance cock, but the top side isn't really moving at all.  I'm not sure how to rectify that as it seems that something is impeding the spring at the regulating end of the balance.

Any ideas?

[Nucejoe]

To go with this hairspring it needs to be repaired first.

I'll be happy to work with you to build a balance complete with the balance you have and the repaired hairspring .

Regs

 

[JohnR725]

21 hours ago, SAK335 said:

I found a replacement and installed it,

Just to be clear you replace the hairspring or the balance complete?

It always nice to give us more than one position on the timing machine like it's a wristwatch maybe crown down that's a common position.

Then fixing hairsprings requires a lot of practice. Preferably practicing on junk hairsprings before you have to practice on the real thing.

21 hours ago, SAK335 said:

Beat error is OK once the adjustment arm is maxed but climbs as you move the adjustment arm to the middle of the range.

I'm a little confused here? It looks like you don't have a movable arm for the beat error? Then it is not really acceptable because I don't actually think the numbers are technically correct anyway. We deal we get a better idea if you put a crown down position but the lines look to rough the  it doesn't quite look right and you do need to straighten out the hairspring before he can deal with any of this.

 

[SAK335]

To be clear, I replaced the complete balance because it was what I was able to find.

Yes, the watch has a non-moveable stud carrier.  I mention beat error because if you move the adjuster, the beat error changes pretty dramatically.  When it's all the way to the "slow" side, the beat error is over 5ms, but if you move it all the way to the "fast" side it's like 0.5ms.  I thought that might be information that might help figure out what is going on here.

I've taken more timegrapher photos.  From top to bottom they are: Crown Down, Crown Up, Dial Up.  The original timegrapher photo was Dial Down.

 

[nickelsilver]

The hairspring needs to be adjusted at the stud, and then along the first coil past the regulator to be concentric with the balance center. It's way off, this is what's giving you your beat error change. You can probably see the spring body shifting as you move the regulator now. For the slow rate, check that the regulator pin is straight and close to the "boot", there should only be about 1 hairspring thickness of freedom (or less in many cases).

 

To adjust the spring from the stud, it would be best to remove the hairspring from the balance, install it in the overturned cock, and adjust. When you are happy with the curve that the regulator follows, you will most certainly need to make a new adjustment at the end of the regulating curve to center the spring. The collet hole will be directly over the balance jewel when it's good.

 

In the pic you can see a circle concentric with the balance center, and an approximation of the bends necessary at the stud, and where to make the additional centering bends at the red arrow.

 

 

[jdm]

13 minutes ago, nickelsilver said:

In the pic you can see a circle concentric with the balance center, and an approximation of the bends necessary at the stud

So in this case it doesn't seem possibile to have a constant circle section between stud and regulator? I was thinking that they should be equidistant from the center to allow that.

My other comment is that the OP should reverse whatever he did to the previous pictures, in the last ones the amplitude is so low that all numbers are meaningless in my opinion.

[Klassiker]

It looks as though the hairspring is fouled on the centre wheel.

[SAK335]

2 minutes ago, Klassiker said:

It looks as though the hairspring is fouled on the centre wheel.

I just looked, as I've had that happen on another watch, but there is plenty of clearance between the spring and the wheel.

[Klassiker]

Does the hairspring now have the shape described by Nickelsilver above?

[SAK335]

25 minutes ago, nickelsilver said:

For the slow rate, check that the regulator pin is straight and close to the "boot", there should only be about 1 hairspring thickness of freedom (or less in many cases).

OK, understood.  I mentioned that I bent this when I first installed the balance complete, and had to straighten and bend it back, so it's quite possible I've not gotten it adjusted correctly.

26 minutes ago, nickelsilver said:

To adjust the spring from the stud, it would be best to remove the hairspring from the balance, install it in the overturned cock, and adjust. When you are happy with the curve that the regulator follows, you will most certainly need to make a new adjustment at the end of the regulating curve to center the spring. The collet hole will be directly over the balance jewel when it's good.

OK, I've seen a couple videos of this being done, so I'll rewatch and see what I can do.

[nickelsilver]

24 minutes ago, jdm said:

So in this case it doesn't seem possibile to have a constant circle section between stud and regulator? I was thinking that they should be equidistant from the center to allow that.

My other comment is that the OP should reverse whatever he did to the previous pictures, in the last ones the amplitude is so low that all numbers are meaningless in my opinion.

It can definitely be made concentric, like in the pic. Tons of watches have the stud on a different center than the regulator, with appropriate bends to the hairspring to center the regulator curve.

[SAK335]

52 minutes ago, Klassiker said:

Does the hairspring now have the shape described by Nickelsilver above?

The spring is moving back and forth underneath the wheel.  It just so happened that when I took that photo, the spring had moved "in" and looked as if it had aligned with the wheel.

[SAK335]

I think this is what you're telling me that I need to do:

 

[Klassiker]

With the balance static, the hairspring should have the shape described by Nickelsilver. You will need to manipulate it according to his instructions. Not easy, but you could not get better coaching.

[Klassiker]

That's a good video, showing exactly what you are trying to achieve.

[JohnR725]

2 hours ago, jdm said:

My other comment is that the OP should reverse whatever he did to the previous pictures, in the last ones the amplitude is so low that all numbers are meaningless in my opinion.

Did you notice the first picture the amplitude looked really good in fact it looked too good for what were seeing? This is why always ask for a second position like crown down because if there is a amplitude reading issue a lot of times will show up in another position.

Then all the rest of the pictures basically show random dots so all it's really telling us is you're having a problem and until you get the problem to go away the timing machine is now worthless other than it's telling you you're having a problem

Basically this means you have to fix the hairspring problems and the timing machine problems should go away. Also make sure the hairspring is flat and not touching the balance arms.

 

[jdm]

15 hours ago, JohnR725 said:

Did you notice the first picture the amplitude looked really good in fact it looked too good for what were seeing? This is why always ask for a second position like crown down because if there is a amplitude reading issue a lot of times will show up in another position

I think you mean the reading is double the actual amplitude. Whilenrhat is surely possible, some elements don't match. In first pic with double reading actual could have been around 120deg, with discernible slow and poor pattern. Then last picture, low amplitude for sure, rate all over the place, no pattern.. meaningless. So I wonder if anything has changed in between.

[SAK335]

The amplitude was actually really good when I first installed the balance (after fixing the issue with the balance adjuster pin) and the lines were straight-ish.  But the watch was running super slow.  I made a very minor adjustment to the hairspring near the stud to try to get the hairspring rounder, and the amplitude dropped down into the mid 100s as a result.

[Nucejoe]

 Can you show a side view video of the coil when running, if not remove the oscilator to see/show the coil's top&side view. 

 

[SAK335]

Link to a video of the balance from side and top view:  https://photos.app.goo.gl/QP98KUEQMKv8VKr97