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Electronics for dummies - McComb G.

McComb G., Boes E. Electronics for dummies - Wiley publishing, 2005. - 433 p.
ISBN: 0-7645-7660-7
Download (direct link): electronicsfordummies2005.pdf
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Four risers separate the two deck pieces. You can use standoffs for the risers. Standoffs are lengths of metal that have threads on either end to accept common sizes of machine screws (these threaded ends are referred to as ‘female’). The longer the standoff, the greater the distance between the two decks. You can get standoffs at electronics supply stores. Or, you can use 2-or 1>2-inch long 6-32 machine screws that you can get at most hardware or home improvement stores.
Keep these points in mind when choosing what to use as risers:
^ When using standoffs as risers, the minimum length that you can use is )2-inch; 1- or 1>2-inch standoffs work even better.
^ If you’re using machine screws as risers, remember that the length of the screw must accommodate whatever distance you want between the deck pieces, plus the thickness of the deck piece material, plus the thickness of the retaining nut. For example, if you want 1 inch of clearance, and you’re using X-inch thick wood or PVC, then the machine screws must be at least 1X inches. The remaining 1/4” is just enough for you to fasten a nut at the end of the screw.
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330 Part V: A Plethora of Projects
Building the Body of the ‘Bot
Now that you have your building plan and materials in hand, you’re ready to actually start construction. So put on your hard hat, and read on! (Oh, and don’t forget to grab safety glasses to protect your eyes.)
Cutting and drilling the pieces of a robot body
The first step in the building process is to use the robot layout from Figure 15-1 to drill holes for mounting parts, and then cut out the deck pieces.
Follow these simple steps to make the body pieces for your Rover robot:
1. Lay out the holes and cutting dimensions from the template in Figure
15-1 directly on the wood or plastic material. Or better yet, draw them first on a piece of paper, then tape the paper over the wood or plastic material you are using for the decks.
2. When all looks right, drill the holes for Rover using a /8-inch drill bit.
You can use a hand drill (manual or motorized), but a drill press helps you to make more accurate holes. The distance and alignment of the four holes that you use to mount the two motors are the most critical.
3. After you finish drilling, cut the pieces to size.
You can use a hacksaw (see Figure 15-2), coping saw, jigsaw, band saw, or scroll saw — whatever you happen to have in your shop. We prefer the scroll saw because it provides more control.
4. Sand down the corners of the pieces to produce a beveled edge. This removes the sharp angles at each corner.
Use a motorized sander, such as the one that you see in Figure 15-3, to remove the sharp corners. But if you don’t have this tool, use a sandpaper block with 60- or 80-grit paper and a little elbow grease to get the job done.
When you saw pieces without the benefit of a straight edge, you should cut a little outside the line that you marked onto the paper layout or material and then clean up any irregularities with a file or sandpaper block.
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Figure 15-2:
You can cut the Rover pieces using a hacksaw.
Chapter 15: Cool Robot Projects to Amaze Your Friends and Family 331
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332 Part V: A Plethora of Projects
Assembling and mounting the motors
Set aside the body pieces for now and turn to assembling the two gear motors. You put these motors together by following the instructions that come with your motor kits. Use a #1 Phillips screwdriver to assemble the motors; note that the screwdriver doesn’t come in the kit, so you’ll need to buy one if you don’t already have it. You also need a small hex key wrench. You’ll be happy to hear that the hex key wrench does come as a part of your motor kit.
Figure 15-4 shows how the gear motors should look when you’ve assembled them.
Attach the two motors to the bottom deck using some 6-32 screws and nuts. Refer to Figure 15-5, which shows you how to line up the motors with the holes in the bottom deck of your robot.
Figure 15-4:
A Tamiya gear motor, assembled and ready to go.
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Chapter 15: Cool Robot Projects to Amaze Your Friends and Family 333
Figure 15-5:
The motors attach to the bottom deck of the Rover by using small screws.
Doing a wheelie
With the motors attached, it’s time to secure the wheels in place. Putting the wheels for your little robot buddy together involves two steps — mounting an axle to the gear motor, and then attaching the wheels to that axle.
You get two styles of metal axle in the gear motor kit, one with and one without a hole on each end for a roll pin. (A roll pin is a small stick of metal that comes with the gear motor kit. It’s tiny, so be careful not to lose it!) You use the axle that has the holes to build your robot. You can throw the other axle in your junk bin, ready for another project.
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