File

SECTION
3.1
SIDE LEGS
Side Legs
3.1
I began in Adobe Illustrator with the official Club plans in
vector format for use in the plotter (I’ll explain in a bit).
Using both side and front views, I created a virtual rendition
of the construction. This allowed me to employ a lot of trial
and error to simply see what worked best.
I wanted the legs to be as strong as they could be, so they
are not hollow, but one solid piece. Using the side views
as a reference, I determined how many of each front view I
needed to cut for each material thickness. You can see the
colors above corresponding to the layers in the previous
pic.
This is the plotter at my shop. It’s like an architect’s plotter,
but it has a knife instead of a pen. Illustrator makes vector
paths (those XY coordinates from Algebra), which the
plotter’s blade follows. So, it’s essentially 2-D CADD work
on a big, electronic Etch-A-Sketch with a knife.
When the vinyl has been cut, I weed out all of the excess,
leaving only my templates. Vinyl is the staple lettering
material of every sign shop.
Side Legs
3.1
Another shot of me weeding the vinyl. It’s a rubber-based,
custom-cut sticker that comes on a waxy paper backing.
The plotter cuts through to the backing, so the removal
of excess vinyl is easier. It pulls off with a small pick or
Xact-O knife.
Here is all of the weeded vinyl. I chose brown simply
because we had a whole 24” wide roll of it, and hadn’t
used any of that color in a long while.
Now the vinyl is taped over with 12” wide masking tape. If
you have vinyl cut at a sign shop, the price per square foot
should include weeding and taping.
Another shot of me taping the vinyl. The tape makes it
easier to transfer the cut vinyl to the material while keeping
it as one whole piece.
Side Legs
3.1
After all the vinyl has been taped, it is transferred to the
materials. I used a combination of 3/4” oak plank, 3mm &
1mm polystyrene, & 1/8” aluminum.
I chose polystyrene because it is a durable, weatherresistant, smooth-surfaced solid plastic sheeting that is
easily cut with a utility knife or a bandsaw. It also stands
up to impact well.
Polystyrene is quite different from PVC sheeting (brand
names like Sintra and Komatex). PVC sheeting looks
similar, but is primarily an indoor-only material. The sun
affects it in terms of warping, discoloration and breakdown
of its looser composition. It has a porous surface, not the
glassy smoothness of polystyrene, and when water gets in
those pores, PVC sheets tend to warp, crack and bubble.
Polystyrene is what many toys, model cars and most
common-use plastics are made of. It’s also a sign material,
so I can order it cheap from the warehouse.
All of the templates are transferred onto their respective
material substrates.
The vinyl templates are arranged for the best fit on the
materials.
Beginning with the softest material and a wide saw blade, I
cut out all of the 3mm polystyrene pieces on the bandsaw
(except the shoulders).
Side Legs
3.1
Next came the plywood pieces. While it might have saved
me some cuts if I had glued them all together first, it
would have only been a couple at most. I chose easier
handling over only nominally quicker completion. With a
little practice and a good vinyl template to follow, you can
cut out the tops of the legs without a circle-cutting jig.
The piece shown above is one of the three of five layers
that make up the main leg. The two outer layers do not
have this indented cut. The way the middle three layers
are cut (see the first pic on this page) makes up the hollow
for the shoulder cylinders, and keeps me from having to
try and hand-router them out later.
The final cuts with the wide blade are on the aluminum. This
1/8” highway-grade aluminum will add a bit of strength to
the ankle and the pivot point at the very bottom. Aluminum
can be shaped with all the same woodworking tools. If you
can, run the saw at a lower speed, or move very slowly to
keep the blade cool.
Here’s a shot (with the vinyl masks still on for contrast) of
how the layers will form the hollow under R2’s shoulder.
Side Legs
3.1
And a long shot of the same thing, showing the entire leg
main assembly.
And a quick setup to make sure I’m still consistent. It looks
good so far. Now back to the shoulders.
Before gluing, I removed all of the vinyl templates and set
all of the pieces up once more to make sure that I had them
all in the right order, and that they all still fit correctly.
If “Measure twice, Cut once” was ever relevant, then
“Mock-up forty times, Glue once” is even more so. Now
would be a good time to catch mistakes.
Side Legs
Here’s another closeup of the shoulder hollow, without the
vinyl.
3.1
Liquid Nails is applied between each layer, and the whole
thing is clamped together.
Since Liquid Nails is a thick, caulk-like glue, I spent the
next fifteen minutes adjusting and re-clamping because
the layers would “float” out of place.
Once the ‘Nails set, though, it was a different story. These
pieces are now stuck for eternity.
Notice, the main leg is composed of five layers of
alternating wood and styrene, but I only glued together
the middle three.
Not gluing the outer layers yet allowed me to sand down
the inner three for a smoother cross-section inside the
shoulder hollows. The droid will end up being “veneered”
in 1mm styrene, so my main goal is just to get the layers
roughly as close as possible, hence the abrasive metal
file.
Side Legs
Once the shoulder hollows are rasped out, I glued the
outer layers onto the whole. Now, except for the ankle, the
leg is at it’s official thickness.
3.1
The layer of aluminum on the front of the ankle has had
holes drilled through it. Since this is a very smooth metal
sheet, I wanted to ensure that if the metal somehow
slipped, the ‘Nails would still hold it in by grabbing the
layer of styrene above it.
I found that blobbing on the Liquid Nails on the main leg
left a bit more gap than I’d prefer, albeit it was only a 1/16”
gap. With the concept of the epoxy on the shoulders, I
began from this point on to spread my ‘Nails. It leaves
almost no gap, and the thinner layer of ‘Nails sets a lot
quicker.
The new layers of aluminum and styrene are glued in
place.
Side Legs
3.1
I veneered the edges of the legs with 1mm styrene. I left
the ankles alone for the moment.
The styrene looks good, and is (and will remain) a 90°
angle- no sanding required.
The insides of the shoulder hollow were also veneered.
Aside from the outside edges (made from the outer layer
of 3mm styrene), the hollows have four planes. I measured
and cut 1mm styrene to fit each plane, then glued them
into place.
The legs are puttied and sanded smooth.
Side Legs
3.1
By again knocking off the perfect angle, the corners are
not noticeable, and the veneer seams melt away.
Instead of trying to cut and glue tiny strips along the edge
of that 3mm styrene, I left it short and sanded it down to
a smooth transition. After this pic, I hand trimmed the top
edge of the veneer to match the stright line of the hollow’s
inner plane.
For the rounded ankles, I applied flatpack templates to
some .032” aluminum. It’ll bend very easily, but still retain
its shape well.
The lower piece was cut out of .080” aluminum, because
it will be giving the rounded portion its structural stability
at the bottom. The slot was cut out with the Dremel, then
smoothed with a metal file.
Side Legs
3.1
The .032” aluminum was wrapped and secured around a
cardboard tube. Wrapping it around a tube ensured it was
curved evenly, and prevented my overzealous hands from
sharply bending it.
Now the ankle is pre-curved, making it mate up to the other
piece a lot more easily. The bottom edge of the curved
piece was also hand-beveled to a closer angle where it
came in contact with the thicker aluminum.
I laid the flat piece on my stand, then butted the curved
ankle up to it. I used pliers to hold it in place while I JB
Welded the heck out of it.
Then I JB Welded a small piece over the hole, leaving the
visible indent from the exterior.
Side Legs
3.1
Now to attach the ankles to the main leg... Since JB Weld
oozes, albeit very slowly, I decided to let the goo do the
work for me. I slathered it along the side edges and bottom
of the ankle.
Then I flipped it over onto the main leg. The ankles are
taped into place, and the leg is placed curved-ankle-up,
so that gravity will shift the JB Weld into place and grab
the main leg on its own.
After a few minutes, a peek inside the ankles proves my
theory sound. This saved me from having to try and inject
goopy ‘Weld down into the ankle.
Some JB Weld is also skimmed across the sides of the
ankles.
Side Legs
3.1
Some more .020” aluminum is roughed up on the down
side, then taped into position and left to harden. The other
side if done the same way.
For the mounting holes, a paper template was printed,
trimmed and taped onto the main leg.
The holes were drilled through on the drill press. I actually
just bought this press, and it couldn’t have come at a more
opportune time.
The template is removed, and the bare holes are
exposed.
Side Legs
3.1
A paper template was also applied to the vertical slats on
my frame. The template was done on the computer, so
the precise 36° tilt between the frame and the legs was
already established. This temporary mounting of the legs
and flanges to the frame also allowed me to make sure the
holes all lined up.
The legs were removed, and the mounting holes were
counter-sunk drilled to allow for a 1/2” washer to sit in
there too.
The ankle pivot is also drilled out on the drill press.
A nylon insert was tapped into place. The drill bit wiggled
a bit when boring through that aluminum, but it didn’t hurt
it structurally, and it’s hidden.
Side Legs
3.1
Now to address the biggest flaw in my design: this was
originally meant to be a stationary replica, but the decision
to go mobile was made AFTER I had already made my
solid wood legs.
Now I have to get the wires down to the feet, so I started
by boring a 1/2” hole up the middle of the legs with a 14”
extended bit (previous pic). The hole is slightly off-center
to keep it from running into the bottom shoulder bolt.
At the top of the hole, I drilled a small hole into the tunnel
through the back of the leg to let me know I was straight
and see how clean the tunnel was.
The approximate location of the exit point from the legs
into the shoulders was marked on the flange. This was
really an arbitrary decision, but I did have to keep in mind
the location of the shoulder hub.
Side Legs
3.1
The flanges only were reinstalled onto the body, and the
5/8” hole was continued through the vertical braces to the
interior of the droid.
A line was drawn from the little hole to the place where the
leg was drilled out from the shoulder flange.
A channel was routed from the end of the drilled hole (as
far as it could reach from the ankle) to the shoulder hole.
A slight lip was also recessed along the sides of the
channel.
Side Legs
3.1
A strip of .020” styrene was cut to match the edge of the
lip.
The styrene strip was glued into place over the channel.
The strip extends up under the shoulder flange, so once
the droid is assemble, you won’t even be able to tell it’s
there.
Putty is laid out to even up any dips or reccesses.
Side Legs
3.1
The typical putty and sand routine ensues, until the surface
is nice and smooth again.
The backside of the legs were primed again, and the wires
were run up the tunnels.
To finish off the ankles, an 8”x3” strip of .020” styrene was
cut for each leg.
A layer of JB Weld was slathered over ONE SIDE of the
ankle, and the styrene was lined up and taped in place.
Side Legs
3.1
Once fully cured, the process was repeated for the other
side. The thin styrene was pulled around the pivot at the
bottom, and tape held it tightly in place.
The excess was hand-trimmed and filed down even with
the rest of the ankle.
I find that JB Weld is not only a good adhesive when
mixing media (since it creates no heat or external chemical
reactions), but it also makes a very strong filler in gaps that
may require any reinforcement (mostly due to the handcutting).
The old nylon spacer was replaced with an aluminum
one.