R2-D2 by Dan Baker

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PREFACE: The history behind my 2.0 legs takes up too much room here, so I put it at the end. Click Here

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, seen here. 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. Here's a 10MB QT vid of the plotter working.

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.

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 Exact-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.

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, weather-resistant, 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.

The vinyl templates are arranged for the best fit on the materials.

All of the templates are transferred onto their respective material substrates.

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).

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 needing 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.

At this point I switched to my thinnest bandsaw blade. The thicker one was needed for all the straight cuts and the aluminum, but this thinner one will make the curves inside and around the horseshoes a lot easier.

Even though there were a lot of them, I chose to cut out the shoulder pieces one-by-one.

I left the cut inside the horseshoe loose for a good reason. Even with my thinnest blade, doing this by hand is not entirely precise, and I ended up with a few gouges and some wandering on my test piece.

Instead of cutting the insides with the bandsaw, I hooked up the router attachment on my Dremel, stuck the end in the exhaust port of my vacuum-forming table (it just happened to be nearby), and ta-da! A makeshift router table for small parts!

A sanding head in the Dremel made the inside of the shoulders a snap. I ran the Dremel at about mid-speed (the highest speed got the styrene too hot and it kept melting into a band of hardened plastic around the bit).

Soon all of the shoulder layers were cut out. Each shoulder is made of seven layers of 3mm styrene. Cutting in another 3mm on the inside edge of every other layer will provide the ribbed-shoulder detail of the Kenny Baker R2-D2 unit, seen here.

Here's a shot (with the vinyl masks still on for contrast) of how the layers will form the hollow under R2's shoulder.

And a long shot of the same thing, showing the entire leg main assembly.

Here's the way the shoulders line up. With the vinyl still on, you can see the detail on the inside of the shoulder.

Here's a lower shot of the same, and you can clearly see the way the indented layers line up with the main ones. I've got to give cred to Kelly Krider on this one. He had some good thoughts on the layering method. Check it out here.

And a quick setup to make sure I'm still consistent. It looks good so far. Now back to the shoulders.

For all the layers except the top one, I just cut the holes out on the bandsaw. I did alternate the blade's entry point on each one, to prevent the creation of weak spots on the piece.

For the top layer, I went back to the "router table." With the plunge router bit back in, I just popped up through the styrene and did the same as before.

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.

Here's another closeup of the shoulder hollow, without the vinyl.

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.

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.

The shoulders were glued up one-by-one with Loctite epoxy. Keeping all seven layers lined up took a bit of finesse, but the epoxy fumes kept me in good spirits. :b

The Loctite set pretty quickly, and these things look fantastic. They are now one solid piece of plastic, and being able to hold them without having to pinch them together revealed a good heft to them, too.

The 1/8" birch spacer is also glued onto the back of the shoulders.

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.

The new layers of aluminum and styrene are glued in place.

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.

As for the outside edge of the shoulders, a strip of 1mm polystyrene was cut and glued around the edge. Good-bye sanding, hello perfection!

To make it easier, I ran the ege of the shoulders through the bandsaw once more, then used the metal file to smooth out any anomalies.

A thin layer of Liquid Nails set fast, and the edges turned out fabulously. Now the corners are square all the way around the outside edge.

Another shot showing the top of the shoulder. The 1mm styrene is flexible enough to be easily bent around that curve, but retains enough rigidity to hold a nice, flat shape.

Extremely close up, you'll see that even the veneer is not perfect. these gaps (actually caused by the fact that I cut this all out by hand) will be filled with putty and sanded smooth. Cutting the holes after it was glued together may have prevented some of the variance in the inner walls. Next time...

Bondo Glazing & Spot Putty fills in the gaps, sets very hard, and sands nicely to a perfect finish.

A quick coat of primer vindicates the process. Any gaps that were there before, are now gone.

I finished puttying and sanding the outside of the shoulders. The results were quite impressive.

By knocking off the perfect 90° corners and giving the horseshoes another coat of primer, you can't even tell the veneer is there. It looks great.

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 insides of the shoulder holes are veneered the same way. Each piece is cut to length, then coated with glue and held in place for a minute or so.

Even a thin layer of epoxy between each layer of styrene is enough to thicken the shoulders an extra millimeter, so I left the styrene a bit long vertically.

A few slices with the utility knife brings the hole veneers to the correct level. You can see the places where the Dremel jumped and accidently hit the sides earlier, and why it won't be a problem.

Here's a long shot of both shoulders after veneering the holes. The putty will fill in all of the gaps.

The legs are puttied and sanded smooth.

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.

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.

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.

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.

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. A couple had to be hand-drilled a bit to fit the mounting bolts.

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.

Now to address the biggest flaw inmy 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.

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.

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.

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.

The A layer of JB Weld was slathered over ONE SIDE of the ankle, and the styrene was lined up and taped in place.

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 hand-cutting).

The old nylon spacer was replaced with an aluminum one.

Now to mount the shoulder horseshoes. First, I traced the horseshoe onto paper and made some on-the-fly decisions about where I want to add mounting points.

Using the paper template, I poked holes through the paper into the horseshoe and the main leg.

I drilled out the holes for the mounting system. I left the side with the shoulder hydraulic empty, since I didn't want to risk geting too close to the edges and causing breakage.

These are grill guides. They are press-fit mounting brackets for speaker cabinets. I got them at Parts Express here. I saw this idea on one builder's site, and loved the concept. I've never seen it since, though, so I hope it holds.

The hole for the female plug is counter-sunk a bit to make room for the lip at the top.

The male and female plugs are tapped into their corresponding holes.

Just line them up and press firmly. The shoulder snaps into place, and feels nice and tight. It also releases easily for future upgrades or repairs.

The center leg began as two pieces of 3/4" birch ply laminated with .020" styrene, and one piece of 3/4" birch ply laminated on both sides with .125" styrene, to bring the thickness up to an even inch.

Each of the three pieces were cut on the bandsaw, and the ankle pivot was drilled.

With the styrene layers pointing out, the three sections were glued together.

A mounting plate and angle brackets were created to install the leg.

The center leg is attached to the mounting bracket.

The center leg assembly is installed to the frame for testing. The solid wood leg proved to be very tough.

After testing, the center leg was removed and skinned with styrene on the front & back.

The three curves faces around the bottom of the ankle are also skinned in styrene.

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PREFACE

I had actually spent a few months working on the legs before I even started this journal. I got acquainted with a few different materials, and even learned to hate a few. There was a major problem, though. I was working with wood only. Since this was originally going to be a stationary replica, I wanted the legs to be strong. Solid. Well, between layers of oak and birch I had a pair of decent legs. I was pleased with them, no doubt. I went the way of some who build droids, choosing to spend the majority of my time in the finishing of the wood. It worked great.

I would get the layers lined up, glued and set overnight, and sanded down to an almost perfect match. Then I would use Bondo glazing putty (great stuff) to even the pieces out, and as a skim coat for the surface of the wood. Well, the thing that finally frustrated me to the point of scrapping them in search of something better was that I would spend hours coating, drying, and sanding down to a glass-like surface, only to have everything that bumped into the legs leave a big dent. Every single time. The wood and bondo just weren't hard enough to stand up to any impact.

There were other problems, too. When the plywood was glued up, small beads of Liquid Nails seeped out of the cracks in between. It gummed up my sandpaper until I finally scraped it all off with a utility knife. But then, even after coat after coat of puttying and sanding, you could still see the lines of glue. Also, after so much hand-sanding, the edges moved farther and farther away from square. In the end, the top of the leg and the top of the shoulder horseshoe were off by a full quarter inch. Unacceptable.

I was working on the legs, thinking about this, when I looked at the table I was on and saw the answer. I had a dozen sheets of 1mm polystyrene (I use it for vacuum forming), and it hit me to screw all this sanding and use the polystyrene to "veneer" the entire droid. Now, with having a perfect droid a more viable option, I naturally started over. I am glad I did, and since I was starting over anyway, decided it would also be a good idea to compile this log as a companion to the project. top