Much like most scratch-built items in R2 building, Artoo's outer legs and center ankle are built up of layers of varying thickness using one material or the combination of different materials, whether it be plastic, wood or metal. These layers are specifically arranged so they match the dimensions of the club blue prints. Consulting Victor Franco's leg tutorial , I gained an understanding of how all the layers of plywood were put together.
Materials & Tools:
Outer Legs / Center Ankle Layers:
1 -3/4" x 4' x 8' Birch Plywood
1 -1/2" x 4' x 8' Birch Plywood
1 -1/4" x 4' x 4' MDF Board
1 -1/4" x 4' x 4' Hard Board
_______________________
Router/ Router Table
1/2" Router Template Bit (w/ bearing)
Table saw
Power Hand Held Drill
Drill Press
General Hand Tools: Hammer, Screwdriver, pliers, etc...
Power Hand Held Jig Saw
Power Circular Saw
Power Miter Saw
Disc/Belt Sander
Assortment of Sand Paper
Pencil
Metal Ruler/Straight Edge
Digital Caliper
Compass (to draw circles)
Assortment of Clamps
Dremel w/ Router Attachment
Pneumatic Brad Nailer + Air Compressor
1 -1000 pack 1 1/4" Pneumatic Brad Nails
1 -Bottle of Wood Glue
1 - 1/2-Pint Elmer's E848D12 Carpenter's Wood Filler
Several cans of Rustoleum White Spray Primer
Several cans of Rustoleum Satin White Spray Paint
1- Can Valspar - Bright Silver Spray Paint
Most importantly: Eye, Ear and Respiratory Protection
* I actually used every tool I owned for this part of the project!
Making the Templates
Two uniquely shaped templates were needed to create the different layers of the legs. There was one for the outer layers and one for the inner layers. The templates had to be as perfect as possible or else the defects would have been replicated in all the layers I made.
Using the dimensions in the club prints, labeled "Assembly Outline Drawing" , I redrew the general outline by hand on a 1/4" MDF board. This one was made particularly for the outer layers.
A power hand held jigsaw using a fine-cut blade was used to carefully cut the straight portions of the template. When I got to the circular portion (shoulder) I cut a 1/8" margin around the outline because I wanted to use a more accurate method of cutting a perfect half-circle. To achieve this, I created a jig that allowed me to pivot the template against a disc sander. I did the same for inner leg layer template as well (not shown).
The results for both templates turned out pretty good. The inner layer template is the one on the left.
Cutting the Layers
Using a template router bit, I was able to route several copies of all the needed layers for the legs.
Shown below are all the cut layers used to create one leg. Because Birch plywood is not so common in 1/8" and 1/4" thicknesses, alternatively, I used hardwood board and MDF board, respectively.
In order to get the "armpits" to spec, the outer layers needed some special attention using a router, Dremel, and wood chisel.
The center ankle was made up from a total of four layers: two inner layers of 1/2" Birch plywood sandwiched between two layers of 3/4" Birch plywood. Since the center ankle was only one unit, no templates were needed. The outlines from the blue prints were just hand-drawn directly on the wood.
Just to get an idea how they look at this point, here they are roughly put together with clamps:
With respect to the blue prints, the curved section of the ankles were made from cutting several segments of 6.0" diameter circles made from 3/4" Birch plywood and then gluing them together.
Rather than cutting each individual segment one by one, to expedite the process, I screwed together two circles and cut them as one piece. This way, one chop from the miter saw got me two segments. As you can see, in the pic below, I used a piece of scrap plywood (green arrow) to clamp the circular pieces in place. There was no way I was putting my hand near the blade! Safety comes first!
The red line you see, in my dimly lit garage, is a laser, which is a an unreliable feature that comes with many of today's power tools. I say this because you can't even see the laser if you use this outside or with a bright light.
To make one piece, it took about six segments that were glued and clamped together...
...which equated to a total of 24 segments for both legs and center ankle.
The next day I had to cut a 55 degree angle on each of the curved ankle pieces. This was very tricky, since my cheap miter saw maxed out at 45 degrees. To make the correct cut, I had to create another jig that angled the piece an additional 10 degrees from the horizon. I mounted the jig with a combination of clamps and viola!, 55 degrees.
Here's how two newly cut pieces looked like.
After the pieces have been filled, sanded and followed up with a few coats of Rustoleum white primer, they were aligned, glued, and secured using a pneumatic brad nailer.
Here's how they look before the lengthy process of filling and sanding. According to spec, the holes, located in the outer side of the shoulder, were drilled. On the inner side, 1" and 3/4" gas pipe flanges, which will be later used to connect the legs to the frame, were installed. We will visit this process again at another time.
At this point, the filling-sanding-priming-filling-sanding-priming process began. Then it was repeated over and over and over again until the wood grain and the surface imperfections were all gone. As they say, patience is a virtue.
The 3/8" hole near the apex, which supposed to use a 3/8" bolt to connect to the foot motor mounts, was drilled 1/8" lower than the blue prints called for. This was recommended to eliminate the foot shell-to-ankle clearance problem that builders have experienced when Artoo was in his three-legged stance. ...and what great timing that the newly drilled holes could now double as an ankle joint and a paint drying apparatus!.
The legs were primed again and finally painted using Rustoleum satin white. They were hung and left to dry in the garage for a week. Also notice the flanges (used for electrical conduit) installed on the outer legs. This flanges will be used later as a way to connect the legs to the body.
Other Details
According to the blue prints, there is a channeled section located at the angled face of the ankle (green arrow). I simply dug this out with a chisel, then lined the inside with left over styrene from the skins. This great idea came from Victor Franco's leg tutorial.
I purposely made the styrene lining stick out a little past the surface so I could sand it flush. The gaps were later filled and sanded smooth.
Using a two-part filler (Bondo) made things go alot quicker as it only took a few minutes before I could begin sanding it.
After filling, sanding, filling, and sanding more areas of the leg (it never ends!), primer was applied once again and left to dry for 30 minutes. The entire leg was then immediately painted with Rustoleum satin white (again).
The following day, the "armpits," were painted with Valspar bright silver. As you can see, the styrene patch really cleaned things up nicely.
A beautiful detail that I really admire is the thin channel that goes around the periphery of the lower middle section of the leg which is also continuous on another separate piece called the "booster covers" (I will cover this later). In the final product, this channel was painted to simulate "bare metal," which supposed to indicate a metal foundation beneath the white exterior. To accomplish this, the 0.1" wide channel was created by clamping a metal straight edge and using a Dremel with a router attachment adapter with an appropriately sized routing bit. I had to make a few practice runs on a few pieces of scrap wood before I used it on the leg that took so long to make. God forbid I screw that up! After finding the optimal RPM and the optimal speed in which to move the Dremel along the straight edge, I followed through, on each side of the leg, with a steady, continuous pass. It was a scary endeavor, but a successful one.
Here's how the leg looked with the channel painted with Valspar bright silver.
coming up next... Cutting The Dome
