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"He said it would
interfere with the compass. He said I should use brass or stainless hardware,
which is fine but i can not find nutplates made of
this."
I stopped by the hangar today, got a K1000 nutplate
from the parts drawer and placed it right next to my mag compass, actually
touching the housing. I then moved the nutplate all around the compass
within a half inch of the compass housing. At no point could I detect any
change in the compass indication. I then got the pocket compass I
carry when I go hiking. (Never really used it while hiking; I just always
carried it.) It's a good compass; fluid damped with a very low friction
pivot and quite sensitive. At 1" from the endpoint of the compass
needle I saw a very small deflection, less than 2
degrees, when moving the nutplate around. At 1-1/2" there was no
visible movement of the needle. No matter how I moved the nutplate
around if it was than an inch from the needle nothing
moved.
Unless you're going to rivet a nutplate to the face
of your compass I don't think you need to worry. Besides, adjusting the
compensation screws when you swing your compass should correct for any small
amounts of ferrous material near the compass.
By the way, small magnets are an entirely different
story, which should be no surprise. I found a small
round refridgerator magnet that caused a noticeable defleciton, up
to 5 degrees, in my pocket compass from as much as 2 feet away.
A magnetized screwdriver produced similar results. I suppose if your
nutplates have been stuck to a magnet for a while they might cause some compass
error within 3 or 4 inches of your mag compass, so don't use a magnetic pickup
to get nutplates out of the parts drawer.
Tom Gourley
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