> I'm the Barry who agrees with you... And, this is one of the more
> interesting topics relating specifically to the wobbly column of this
> particular milling machine. :) I'm wondering why people aren't
> considering the 2000 year old techniques used by architects in Japan
> (through to today) where you create a structure inside the structure
> you want to dampen that creates balanced movement to counteract the
> troublesome movement. I'm not a mechanical engineer so this is over
> my head. But, from an idea perspective, it's got to be better than
> dangling cinderblocks over your head.
There is a technique in vibration dampening that involves adding a
mass/spring system tuned to the frequency you want damped. A frequency
driving the system or a natural frequency of some part of the structure.
A problem that this creates is that it adds two new natural frequencies,
one above and one below the original! A special case is in large radial
aircraft engines where one or more counterweights are suspended on short
arms to create pendulums tuned to the frequency of the power impulses.
In this special case the pendulum is driven by centrifugal force which
varies with RPM as does the driving impulses. Thus the system is always
in tune and well damped! Sadly such a neat system cannot be applied to
the mill as the impulses vary with RPM, number of teeth, and other
parameters. So other forms of dampening must be applied! Bill in Boulder
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