Re: [CAD_CAM_EDM_DRO] Re: vibration damping materials

Les Watts wrote:

>What is incorrect is the statement about similarly
>stiff damping having the same resonant frequencies
>and therefore not doing anything. If you put together
>two structural members of the same stiffness you will
>have something twice as stiff! The resonant frequencies
>and Q will change.
>
>

If you put two objects with the same natural resonant frequency together
with
a resilient material between them, with the thickness of that material
carefully
chosed to accomplish a 180 degree phase lag between them, the damping can be
astonishing, sometimes 1000 times! Exotic contraptions of that sort are
used
in helicopters and such.

Hoyt wrote :

>>Sorry, but it's just not so. For example, boring bars can be damped by
>>filling with mercury. Or they can be damped by filling with lead or steel
>>shot. Or, I damp them as needed by strapping on a few tool bits with
>>
>>
>rubber
>
>
>>bands.
>>
>>

You have to separate vibration damping from basic stiffness. No
vibration damping material
is going to improve stiffness. While boring bars need to also damp
vibration, they must first
be stiff enough to resist the cutting forces with small enough deflection.

Jon