Page 181 - Robot Builder's Bonanza

150 RAPID PROTOTYPING METHODS

foam, usually either 1/32″ or 1/8″ thick, and from 1/4″ to over 1″ wide. The tape is coated
with an aggressive adhesive on both sides. To use, peel off the protective paper and apply the
tape between the parts to be joined. The adhesive is pressure- sensitive and cures to a strong
bond within 24 hours.
Many consumer- grade foam tapes are engineered with an adhesive that never fully cures.
It stays gummy so that the tape can be more readily removed from walls. Maybe this is what
you want, or maybe not. For a more permanent bond, look for industrial- grade double- sided
foam tape; it’s available at better hardware stores, as well as industrial supply mail- order out-
lets, such as McMaster- Carr. One such product is 3M VHB self- adhesive tape.

CABLE CLAMPS
Motors need to be fastened to the base of the robot in such a way that they won’t easily come
off or go crooked. Motor shafts akimbo result in misaligned wheels, which make your bot
harder to control and steer.
When using round motors (the most common kind), look for suitably sized plastic cable
clamps, available at hardware stores and online at computer accessory outlets. These clamps
can accommodate cable thicknesses from 1/4″ to over 1″, and are secured to a surface using
screws— see Figure 14-5 for an example. Use one or two clamps as a motor mount; if the
motor is a bit too small for the clamp, wrap electrical tape around it to thicken things up a bit.

When using just a single clamp per motor, you’ll need a way to keep the clamp from pivoting at
G its fastener hole. You can try tightening the fastener as far as it’ll go, but a better method is to
put “stops” in front of and behind the clamp. The stops— which can be something as simple as a
screw head sticking out of the robot’s base— prevent the clamp from moving. For larger motors
you can use two clamps, with the mounting holes on either side of the motor.

ALTERNATIVE ADHESIVE DISPENSERS FOR RAPID PROTOS

Typical adhesives are dispensed from a tube or bottle. There are other methods, too, and
many of the following ones are easier to use for making rapid prototypes. Give ’em a shot.

Glue Dots, a trade name, are representative of a method of applying premetered adhe-
sive. The dots are provided on a long roll and can be applied by hand or by machine.
The dots come in various “tacks”: high- tack provides permanent bonding, and low- tack,
a temporary sticking place. The dots cure upon pressure.

Figure 14-5 Cable clamps, designed to
hold bundles of wires or cables together, can
be used to attach small motors (and other
things) to a robot.

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