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To begin building our skeleton we
must first address the special
joints this will use so the arms
are adjustable to the right
position once it's completed and
the knees will bend while in
action. This joint is achieved by
cutting a scoop out of the front of
the lower leg section for instance,
and a larger scoop out of the back
of the same section so that the
upper leg will be able to slip down
inside the two ends now sticking up
on each side and will be able to
bend one way, just like a real knee
or elbow. Of course the upper
section of pipe will need to be
rounded at the end to allow for a
"ball" for our "socket", so that
will be the next step. Let's take a
look now at the front and back of
our knee here to get a clear
picture of how much of a scoop will
need to be cut from the front and
also the back of the lower section.
The left picture shows the front of the elbow or leg and of course the
right one is the back, showing how the scoop there will
 need to be lower. If you
look closed not only is the end of the upper piece rounded at the end, but the
inside of the lower part is belled out and the inside edges have been beveled
inside the cut out to allow more space for the top piece to move freely inside
the joint. So how did we round the one and bell the other? It wasn't that hard.
 To round the end of the upper section I used a wine glass, as it had a
rounded bottom inside and I need to use that as a mold for the plastic. The heat
gun brought the PVC up to a soft, pliable point in just a couple of minutes and
I simply pressed the end to the bottom of the glass and held it there
until the plastic cooled. You can also pour cold water in the glass and have
this set in a couple of seconds to save some time. Once you have cut out
the
 scoop from the front and from the back of the top end of the lower section,
you will need to bevel the inside edges as covered in the last set of photos
above. Then you will be ready to bell out the top "ears" and the pipe
itself enough to accept the upper piece. You will do this by heating up the
entire area with the hot gun as with the upper piece and then once hot enough,
simply press the rounded end of the other piece down into the socket and hold
the ears against the upper piece as it cools so the ears are fairly snug against
it so the socket isn't all floppy and loose. Then drill a pilot hole through
each ear into the upper piece so the two are lined up. Now remove the top
section and drill each ear out to a large enough hole so your #8 x 3/4" pan
head screw slips through it without rubbing too tight. This way once the screw
has been sent in to the upper piece to complete the socket, the lower section
will swing effortlessly.
Go ahead and assemble the arms (each section of which is 11" long) and
both legs at this time so once the chest has been assembled you can complete
your skeleton with a couple of screws in each joint.
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