I - Base assembly
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The base assembly consists of 4 pieces of 3/4" plywood. There is a
base (A), 2 roughly triangular uprights (B)
and the tilted platform (C). The angle depends on where you live, so you
will have to modify the dimensions in the drawings to suit your location.
I live at 36° North, so I use this angle. Look up the angle for your
location by following the directions in the sidebar. I use glue and drywall
screws to put the base pieces together. The slanted piece also gets 2
strips of metal
(D), cut from the same stuff as piece (xxx) described below.
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How to find your longitude and latitude
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Of course you can do it the old-fashioned way and look in an atlas, but
since you are sitting in front of the screen, you can do this:
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Go to mapsonus.com
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Once there, click on MAPS
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Fill in your address, and get the map
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Below the map, there is an option "Map-Clicking
will..", and there you choose the option "Show Lat/Long"
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Now click on the map, and you got your coordinates!
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You need to be able to precisely level the base. This is done with
a bubble level glued to the base plate, and using the 3 adjustable feet.
At the local hobby store I bought some 1.5" toy wheels. These
are made out of maple, and have holes in them just big enough for a 5/16"
bolt. Take 3 5/16"×3" carriage bolts, and cut a relief in one side
of the wheel for the
square collar. Add a nut and you have a knob. We will use this design for
all knobs on the sunspotter. The ones you just made stick through holes
in which you tap 'T-nuts'. Alternatively you can use a small chisel or
knife to cut a hexagonal space for a 5/16" nut in the underside of the
plywood base.
On the end of the carriage bolts, file a knob that fits into the felt feet.
These are the kind that have felt pad on the bottom, a plastic support
disc and a 5/16" thin metal cylinder sticking up. Normally, you hammer the
cylinder into the 5/16" hole that you find in the bottom of chair legs
(at least the ones made for the American market). Our bolts fit into
these cylinders. To prevent the feet from falling off, file a groove in the
bolt (and also file the bottoms so they're smooth). With tin snips or
scissors, cut a number of small cuts partly down the metal cylinder of felt
feet, and then you can fold the metal into the groove you filed into
the carriage bolt end.
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On the inside of the base I added pockets for unused index cards and cards
with observations on them. You can also see the bubble level glued to the
bottom, and one of the adjustable legs. Down the
center runs a line which points at true North. The compass however points
to magnetic North, which is 12° off to the right where I live, as you
can see in the picture. Look here to find
this magnetic deviation for your location.
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Last update 18 Feb 2000
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