Ricoh 61 Lift Angle 49 degrees

[steve1811uk]

Not really a question but hope it can help someone.

Well I did a bit of dynamic poising of a Ricoh 61 and needed to know the lift angle. To cut a long story short, I couldn't find the information anywhere.

Using some knowledge I found on this board I adjusted the mainspring so that the balance was moving 180 degrees and then adjusted the lift angle on the Timegrapher so that the amplitude was displayed as 180 degrees.

The lift angle was determined to be 49 degrees.

Hope it helps.

[VWatchie]

Any special trick to determine when the balance wheel is swinging 180 degrees? I would assume you measure from the point of impact of the impulse jewel, and that being a few degrees off would be OK? I guess making a small mark on the main plate of where a balance wheel spoke is on the point of impact could be a method?

Any reason you needed to know the lift angle to perform the dynamic poising (which I haven't yet tried)? Perhaps the lift angle affects the reported rate of the timing machine?

Thanks!

[steve1811uk]

20 minutes ago, VWatchie said:

Any special trick to determine when the balance wheel is swinging 180 degrees? I would assume you measure from the point of impact of the impulse jewel, and that being a few degrees off would be OK? I guess making a small mark on the main plate of where a balance wheel spoke is on the point of impact could be a method?

Any reason you needed to know the lift angle to perform the dynamic poising (which I haven't yet tried)? Perhaps the lift angle affects the reported rate of the timing machine?

Thanks!

Hi, to see the 180 degrees amplitude is easy as the Ricoh 61 balance has two arms. As the arms reach the end of their travel, just before the motion reverses you will be able to see the arm on the rim of the balance momentarily stop. When you see a perfect overlap of the two arms at the end of their travel you will be at 180 degrees.

It's very important with dynamic poising to know if you are above or below 220 degrees. If you are way off with the lift angle then you could believe you are below 220 when you are above or vice versa. You will end up removing weight from the wrong side of the balance. Don't ask me how I know that

Edited November 29, 2020 by steve1811uk
Corrected 180 to 220

[VWatchie]

Excellent, and crystal clear answers @steve1811uk. Thanks! 

Here's an interesting thread discussing poising including illustrations of what happens at the 220 degrees "magic" amplitude.

7 hours ago, steve1811uk said:

You will end up removing weight from the wrong side of the balance. Don't ask me how I know that

OK, I won't!