Page 142 - Robot Builder's Bonanza

METAL FROM YOUR HOME IMPROVEMENT STORE 111

Table 11-1 Summary of Metals for Robot Building

Metal Common Robotics Main Benefits Main Drawbacks
Applications

Aluminum Bases; arms; all structural Reasonably priced; Plethora of alloys makes
parts lightweight but strong; picking the right one
easy to cut and drill using difficult; can be hard to
proper tools weld
Brass Brackets and straps; Commonly available at Relatively soft; low tensile
structural parts for small hobby and craft retail strength
robots; nonstructural parts stores
for larger bots
Copper Brackets and straps; Easy to cut, bend, and Somewhat expensive;
nonstructural parts shape; readily machined tarnishes easily
Steel Heavy- duty frames Very strong; inexpensive Rusts if not protected; can
be hard to drill and cut
Stainless steel Heavy- duty frames Resists rust and corrosion Can be hard to cut and
drill; more expensive than
other metal choices
Tin* Sheet metal bodies; Soft and malleable; thin Can be hard to find
easy-to- make parts like sheets ideal for robot bodies; locally; look online for
motor mounting straps relatively low melting point “punch tin” sheets used
(450–725°F) for craft projects

* Some sources sell thin sheets of tin- plated steel and call it “tin.” Though not the same, the materials may be interchangeable depending
on the application.

Metal from Your Home Improvement Store

Your local home improvement or hardware store is the best place to begin your search for
metal. Depending on the store, here’s what you may find:

EXTRUDED ALUMINUM
Aluminum comes in all kinds of forms, including sheets, bars, rods, and something called

extrusions. It’s the last form that’s really— and I mean really— useful in robot making. I
started using it for my bots back in the ’80s, when most folks were still cutting out sheet metal
to form robot bodies. Ugh! Extruded aluminum has now become the number one metal for
making homebrew robots.
Extruded aluminum is made by pushing molten metal out of a shaped orifice, as those
Play- Doh Fun Factory play sets do. As the metal cools it retains the exact shape of the orifice.
Extruded aluminum generally comes in various lengths, from 12 inches to 12 feet. My local
stores routinely sell it in 4- foot lengths. It’s often used in home improvement jobs to trim the
edge of wood or tile and to make channels for shower doors.

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