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Dirk's skirt is made a somewhat
differently from Bill's. I wanted a lighter skirt this time, so I decided
to use 1/4" (6mm) MDF. I used construction card strips at the edges
to secure the panels together (some people use fibreglass matting). I also
cut a central plywood ring to give the skirt a little extra support. I'm
not sure if this was really necessary. The way I did this was to draw the
outlines for the top and bottom plywood supports onto a piece of plywood,
then connect the corresponding angles with radial lines, bisect those
lines and then connect them up. This produces a template which exactly
fits half way up the skirt. The centre ring is glued in place. |
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THE HEMIS |
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This time around I decided to go
for bolt-on hemis, as with Bill they are not removable, which was a pain
for painting. With Bill I used plastic balls which I cut in half with a
junior hacksaw. This time I used Christmas decoration balls, which come in
two halves which snap together, so they're not perfectly symmetrical.
Dalek hemis are not a complete hemisphere, but nearly a
half-inch shorter, presumably because of an original push-through design.
To get this effect with a bolt on hemi, I built a jig to cut them down. |
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The bench drill holds a hole saw, which has
been covered in several layers of duct tape(!). This grips the hemi over a
supporting disk which stops it collapsing as it is cut.
The disk is cut from the side by a large
hacksaw, which is held in place by the slots visible at right (the hacksaw
has been removed in the picture on the right for clarity). |
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To the left are the cut and uncut hemis for
comparison. The hemi actually comes out 3mm less than the regulation 100mm
diameter,  which
is slightly visible if you look closely, but not
much. I like it better than the full hemi. Each
hemi needed a small amount of sanding
on the bottom edge to clean it up.
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To attach the hemis, some people epoxy
bolts to the inside, some people fill the dome with insulation expanding
foam. I cut 56 3 1/2" wooden disks with a hole saw and put a nut and
bolt through each. Each of these disks was then glued into a hemi with
bathroom tile adhesive. |
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Here are the hemis bolted in place. I
painted my hemis on the outside, because I didn't want the grip on the
hemi dependent on a layer of spray paint applied with no primer, as I'd
get by painting on the inside.
On the right below are two hemis. The top
one is actually experimentally painted on the inside. The finish does look
significantly better (it looks like black plastic rather than painted
plastic when seen close up). I have recently noticed, though, that my
experimental tugs on the bolt at the back have caused a little white line
to appear where the disk is glued in. There may also be some slight
shrinkage of the adhesive which is causing the paint to separate from the
hemi. In the light of this, I think I'll continue to paint them on the
outside. |
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| THE BASE |
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The base is fairly straightforward, so I
didn't say much about it last time. With Bill I used 2.5" castors,
which turn out to be a bit small. Dirk has 4" castors. Because
they're so tall they're mounted to blocks of wood. The separate base hangs
from the bottom of these, so the bumper doesn't have to be so tall. A lot
of dalek builders do this.
Another change I made is to use rotating
castors at the front and fixed ones at the rear. This helps the dalek move
in a straight line, as otherwise you tend to end up moving sideways a lot. |
