Jim,

There are no rules.  (Great hobby, eh?)  The mass should be placed at the
end of the boom, firmly attached.  Since you'll also need to attach the
copper damping vane, drill a hole in the weight and mount it a few inches
back from the end of the boom.  Since you won't be able to drill exactly in
the center, mount it in such a way that you can rotate the weight until it
does not apply any torque to the boom, then tighten some sort of attaching
screw or clamp.  Just make sure that more than half the weight of the mass
is below the boom, or it will try to rotate.  Remember to construct the
support with this clearance in mind, or the mass will scrape on the base.

In my original Lehman I cut a 6" piece of broomstick, drilled and threaded
it, and threaded the end of the boom into it.  Then I could mount the
damping vane and magnets 6" from the end of the boom.  Why?  Because I used
a steel boom, and it got attracted to the damping magnets!  One little
steel screw can "screw" you up. Use a brass or aluminum rod, probably 3/8"
diameter for good stiffness.

Also, I try to attach the copper damping vane so it sticks out horizontally
at the end of the boom, rather than hanging below.  This way the damping
force is applied in the plane of the swing, and no torque results.  Of
course, then you'll need some weight at the other side to balance the
weight of the copper, so some folks just make two copper vanes, one on each
side.  Then if you need more damping you can just buy another magnet for
the other side.

Gee it would be nice if we could sketch in our emails!

Ted


"JIM MARTIN"  on 12/30/99 01:35:36 PM

Please respond to PSN-L Mailing List 

To:   
cc:
Subject:  Another Rookie question



Thanks to everyone so far, who has provided help in the construction of our
first Lehman.  I have another question, and to all of you,  I'm sure this
will probably come off as seeming as though I am quite dense (hopefully
not,
though 8-), how do I determine how far from the end of the boom to place
the
mass (weight),  and is 5 lbs.  of mass about right?

Thanks again,

Jim Martin


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