Low amplitude after service

[TrungNguyen]

Dear all my friends, I have a problem I want to ask. I was training to service a watch and my mentor gave me a brand new orient movement (46943). I measured the amplitude of the movement to 260-270 before but after cleaning and oiling the movement dropped the amplitude to 220, even 180 when I changed positions, I spent a lot of time to check each small part, all parts are okay, the pivot is not damaged, the balance wheel still works well, i clean absorber again and again, but can't improve the amplitude. After this, my instructor spent lots of time to check again but look like he don't know where is the problem ( I don't doubt the level of my mentor because he has a lot of experience and he can fix tourbilon movement). Thinking about this problem gave me headache.

[Nucejoe]

Tell us details of what lubricants you used, specially on escape teeth, also end shakes on balance and escape wheel.

Edited May 10, 2020 by Nucejoe
Cleaning solutions as well.

[DavidMasters]

Over tightening a train bridge, or balance cock could cause a dropping amplitude. Did the balance regulators get moved? How is the Beat error—better, worse or about the same? Do you now have a magnetized hairspring? There are several possibilities so check one item at a time until you see a change in the right direction.

Regards 

[nickelsilver]

Was the train perfectly free with backlash at the escape wheel with just a couple of clicks of power?

Are you sure you pressed the barrel cap on completely/correctly?

Did you oil the pallet pivots?

Did oil accidentally get on the fork horns/roller jewel?

Did a pallet stone or banking pin get shifted during the service?

Hairspring is flat, centered, clean, demagnetized, and watch is in beat?

 

I have accidentally clamped an absolutely microscopic piece of dust under the barrel bridge once that stuck out just enough to contact the balance wheel. That took some hair pulling to find.

I have also been 100% sure the pallet cock was seated correctly and screwed down well, and been mystified that the balance has poor motion, only to find my mistake.

You should go through step by step, check everything with a microscope or high power loupe, check the train freedom is correct, check that the balance oscillates freely with the pallet fork out, check that the fork pivots, hole jewels and horns are spotless.

[jdm]

3 hours ago, TrungNguyen said:

 Thinking about this problem gave me headache.

I completely understand your frustration. You sit there having checked all you have been taught to check, which I'm sure it's 99% the same of what is has been said here, but nothing has effect. One thing that I can suggest is that you listen carefully to the sound, or look at the waveform. That will reveal if anything is touching or rubbing slight plus other possible issues. You can also record and post it here. 

[Jon]

Is it a new mainspring, or did you clean and grease the same one, as damaging or misshaping the mainspring whilst fitting it will decrease the amplitude, as well as badly greasing it.

Also look at how the hairspring is bouncing between the boot and pin.

It sounds like something you have done whilst cleaning and reassembling it.

Cap jewels don't always fit on the top and bottom the same, as they can be different sizes. Did you make sure the ones from the balance went back on the balance?

Did you peg out all the jewel holes and barrel arbor holes?

Did you check when removing the balance that there wasn't a 'birds foot' scratched into the mainplate to raise the balance slightly, thus giving it more end-shake. When cleaning the parts the 'birds foot' can be reduced or go completely, so it doesn't look like it was even there.

Have you damaged any pivots during cleaning?

How did you clean the movement and with what did you use to clean and rinse?

How did you oil the pallets and with what? That can make a massive difference

Have you stripped the movement again, cleaned and oiled again, or have you done it just once.

As someone has already said, a bit a fluff, dust or hair where it shouldn't be will make a difference

Edited May 10, 2020 by Jon

[TrungNguyen]

11 hours ago, DavidMasters said:

Over tightening a train bridge, or balance cock could cause a dropping amplitude. Did the balance regulators get moved? How is the Beat error—better, worse or about the same? Do you now have a magnetized hairspring? There are several possibilities so check one item at a time until you see a change in the right direction.

Regards

I finally found it. Wheel bridges are too tight. I bought another movement and slowly replaced each of the parts and eventually found the error. Thank you everyone for your interest and support.

[TrungNguyen]

My movement is good now, thanks!