Eta 2390 not running

[Johndub]

Hello all, 

Have this eta 2390 here, and can't get it running. Have cleaned the movement, gear train moves freely without mainspring. Mainspring winds, and when released at the click, let's down as expected. Balance etc looks fine, moves freely. Still no joy though, I've had it apart several times at this stage. 

I think the issue is between the mainspring and the gear train, as it's not transmitting power. I did have to reseat a pivot jewel in the mainplate, at the third wheel - it looks ok and seated flat, but it's possible this might be the problem? 

 

I'm stumped on what to try next, so would welcome any suggestions - it's likely something obvious, but as a beginner I'm probably missing it, 

Thanks 

[Nucejoe]

If the fork doesn't jump to otherside as you give it a nudge, check gears end play in entire of the train backward to the barrel.

During assembly and specially when you refit a jewel, you should check its end shake, it needs some free end play to turn unobstructed.

Make a habbit of checking shakes on each arbour as you disassemble and reassemble. 

The refitted jewel could be pushing on the arbour it bears.

Good luck 

[Nucejoe]

1 minute ago, Nucejoe said:

If the fork doesn't jump to otherside as you give it a nudge, check gears end play in entire of the train backward to the barrel.

During assembly and specially when you refit a jewel, you should check its end shake, it needs some free end play to turn unobstructed.

Make a habbit of checking shakes on each arbour as you disassemble and reassemble. 

The refitted jewel could be pushing on the arbour it bears.

Good luck 

correction, check all arbours end shake throughout the train.

[Johndub]

Thanks, that might explain it. 

This may be a question with no easy answer (how long is a piece of string etc), but is there a rule of thumb as to how much movement or shake there should be? I had to improvise to get the jewel back in place, i guess a staking set would make that job easier - more pressure may be needed than i applied 

[Nucejoe]

End shake can be as small as .01mm just to let the arbour free to move, other factors are to be considered as well, like meshing gear teeth with the pinion of adjacent ones, specially with fork meshing with teeth of escapement wheel on one side of the fork and with the guard pin and roller on the other.

But the answer to your specific question is, end shake can exceed .02mm on arbour in the train as long as no pivit jumps out and gears/arbour engage with adjacents specially if no end stone is invloved, since you wont be measuring and just go by the feel and your own instinct anyway.

I guess we would be more observant of such limits when we get to chrono grades or haute and stuff.

Tough question John, I go hide myself next time you ask question.

 

[watchweasol]

Hi  remove the barrel , balance and fork, with the train wheels in place lift up each wheel and check it drops under its own weight if they are all free and drop ok re fit the barrel and re check , now put a couple of turns on the mainspring and chevk the rotation of the wheels if ok fit the fork and apply power to the train, as Nucejoe explained does the the fork move smartly from side to side when assisted if thays ok then fit the balance and it should start up. What we are trying to acertain the at each stage the train is free with end shake on the wheels.   tech sheet attached.

3400_ETA 2390,2391.pdf

[Johndub]

Thanks for the responses. I took all apart, installed just the third wheel and train bridge - it looks and feels like it's as it should be. Thanks for the details Nucejoe, this is all a bit of a learning curve. 

I'll take it apart again and try that sequence watchweasol, see what it looks like. 

I've got my best technician checking it for me now as you can see in the photo, will see what she says 

[les13]

I've got my best technician checking it for me now as you can see in the photo, will see what she says 

Step back from the table. She’s got this. LOL

[watchweasol]

Hi John  Its no contest  I resign.