Seiko 5740C Lift Angle?

JimInOz · Dec 4, 2024

Has anybody been able to track down the lift angle for the Seiko hi-beat 5740C movement.
Using the default 52º shows me an amplitude of 190º which is low, even for a Seiko.
The low amplitude doesn't seem to affect timing, +1spd, 0º beat error.
However, buzzing along at 36000bph the change of direction of the balance/lever/escape may require a lesser amplitude.

👂👂👂

Deafboy · Dec 4, 2024

I've serviced two hi-beat 4520A movements. I determined the lift angle to be 52 degrees. Both had amplitudes of 210-220 in the horizontal positions and about 10 degrees less in the vertical at full wind. Some parts showed wear. Here's a video showing the impulse facet of a pallet jewel. Lots of torque involved to go at 36000 bph. 😀Despite this, they are excellent timekeepers.

JimInOz · Dec 4, 2024

Deafboy
I determined the lift angle to be 52 degrees.

Thanks for that. I haven't serviced this one yet, just checking things out after receiving it. The roller jewel had jumped out of the horns, probably due to a bump during shipping.
I expect it will look better after a proper service..

Archer · Dec 5, 2024

Deafboy
I've serviced two hi-beat 4520A movements. I determined the lift angle to be 52 degrees. Both had amplitudes of 210-220 in the horizontal positions and about 10 degrees less in the vertical at full wind. Some parts showed wear. Here's a video showing the impulse facet of a pallet jewel. Lots of torque involved to go at 36000 bph. 😀Despite this, they are excellent timekeepers.

Been there, done that on these...parts were difficult to find, even in 2010. Probably much harder now...

Spent a lot of time chasing amplitude, only to realize it was never there to begin with. If your amplitude is hanging around the 200 -220 area, and you have the basics right, timekeeping will be easier as that is the range where poise errors sort of go away...

Seiko 5740C Lift Angle?

JimInOz

Deafboy

JimInOz

Archer

Similar threads

8906 movement lift angle?

Calibre 3861 lift angle?

SEIKO 6217-7000 World Time lift angle (with pics)?

Lift angle for Bulova 10AE?

Rolex 2135 lift angle.

lift angle JLC 977