Tuning Fx Crown: Looking for the "lost Knee"

[Doc_pafumo]

Thank you so much for all the clarifications.
I must admit I'm a bit disappointed—I had always thought that the velocity curve relative to hammer spring preload followed a pattern of plateau → knee → downward slope. I understood the "knee" as what I'm showing in the diagram.

 

[SilentSquirrel]

Thank you so much for all the clarifications.
I must admit I'm a bit disappointed—I had always thought that the velocity curve relative to hammer spring preload followed a pattern of plateau → knee → downward slope. I understood the "knee" as what I'm showing in the diagram.

View attachment 568347

What does the red line going upward indicate, please?

 

[nervoustrig]

I understood the "knee" as what I'm showing in the diagram.

Your markups of plateau and knee are indeed correct.

 

[nervoustrig]

What does the red line going upward indicate, please?

Efficiency expressed in units of fpe/ci.

 

[EPG]

Thank you so much for all the clarifications.
I must admit I'm a bit disappointed—I had always thought that the velocity curve relative to hammer spring preload followed a pattern of plateau → knee → downward slope. I understood the "knee" as what I'm showing in the diagram.

View attachment 568347

Doc,

The author of the HAM article will describe the “knee” as approximately 3% below peak (plateau) velocity.

I tend to think of the knee as the start of the downslope - just below peak velocity.

It’s often hard to pinpoint exactly where peak/plateau velocity is - because of slight shot-to-shot variations.

Tuning is not an exact science… However, if you find the hammer spring preload where velocity is no longer increasing and then back off the preload so that velocity is about 4-5% lower than peak/plateau - you should be at a good place - you can then tweak velocity from there.

-Ed