Robot Builder’s Sourcebook

Metal Stock at the Corner Hardware Store
Materials-metal 307
Have a hankering to construct the next Terminator robot? You’ll need about $300,000 in
titanium to do it. A better idea: Make another robot and settle for commonly available
metal stock, such as aluminum plate, channel, and rod. Your local hardware or home
improvement store is the best place to begin. Here’s what you’ll find at the betterstocked
stores.
Extruded Aluminum and Steel
Extruded metal stock is made by pushing molten metal out of a
shaped orifice. Extruded aluminum and steel come in 2-, 3-, 4-, 6-,
or 8-foot sections; some stores will let you buy cut pieces. Aluminum
is lighter and easier to work with, but steel is stronger. Use steel
when you need the strength; but otherwise, opt for aluminum.
Extruded aluminum and steel is available in more than two
dozen common styles, from thin bars to pipes to square posts.
Although you can use any of it as you see fit, a couple of standard
sizes may prove to be particularly beneficial in your robot-building
endeavors.
• 1 by 1 by 1/16-inch angle
• 57/64 by 9/16 by 1/16-inch channel
• 41/64 by 1/2 by 1/16-inch channel
• Bar stock, widths from 1 to 3 inches; thicknesses 1/16-inch to
1/4-inch
Mending Plates
The typical wood-frame home uses galvanized mending plates, joist hangars, and other
metal pieces to join lumber together. Much of it is weird shapes, but flat plates are available
in a number of widths and lengths. You can use the plates as is or cut to size (the
material is galvanized steel and is hard to cut; be sure to use a hacksaw with a fresh
blade). The plates have numerous predrilled holes in them to facilitate hammering with
nails, but you can drill new holes where you need them.
Mending plates are available in lengths of about 4, 6, and 12 inches by 4 or 6 inches
wide, and also in 2-inch-wide T shapes. You can usually find mending plates, angles, and
other steel framing hardware in the nail and fastener section of the home improvement
store.
Iron Angle Brackets
Extruded aluminum
(and steel) comes in
common bar, angle,
and channel shapes.
You need a way to connect all the metal pieces together. The easiest way is to use galvanized
iron brackets, located in the hardware section of the store. Angle brackets come in
a variety of sizes and shapes and have predrilled holes to facilitate construction. The 3/8inch-wide
brackets fit easily into the two sizes of channel stock mentioned previously. You
need only to drill a corresponding hole in the channel stock and attach the pieces
together with nuts and bolts. The result is a very sturdy and clean-looking frame. You’ll
find the flat corner angle iron, corner angle (“L”), and flat mending iron to be particular
useful.