>

The piano wire is directly attached to the upper main
frame. I didn't use a turnbuckle.
....
The problem
is, I can't get the boom in a center position. I didn't get much
farther. Perhaps the soft soil I live on (clay and sand) causes
the boom proble,?
<

No, the problem is the attachment of the wire to the upper main frame.
The point of attachment has to be slightly displaced towards the wanted
direction of the boom.

Some kind of screw adjustment of this point is desirable, so that the
period of oscillation around the center position can be adjusted to 20
seconds or similar.

Regards, Anders





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