Bot Body Toolbox

The original content for this entry was an except from Chapter 5 of Gordon McComb's Robot Builder's Bonanza, 4th Edition. Changes may have subsequently be made to the text here.

Basic Tools for Constructing Robots ¶ 

Construction tools are the things you use to fashion the frame and other mechanical parts of your robo-buddy. These include such mundane things as a screwdriver, a saw, and a drill.

Take a long look at the tools in your garage or workshop. You probably already have everything you need to build your robot. But if you're short a tool or two, relax in knowing that constructing an amateur robot-at least the ones described in this book-doesn't require anything special.

There are other tools for constructing robot electronics and those will be covered elsewhere.

Tape Measure ¶ 

You need a way to measure things as you build your robot. A retractable 6- or 10-foot tape measure is most convenient. Nothing fancy; you can get one for a few dollars at a discount store. Graduations in both inches and metric is helpful, but it's not critical.

A paper or fabric tape measure-one yard long, available at yardage stores, often for free-can substitute in a pinch but may not be as accurate. They're handy for measuring in tight places.

Screwdrivers ¶ 

You need a decent set of screwdrivers, with both flat and Phillips (cross) heads, as shown in Figure 5-4. These come in sizes; get #0 (small) and #1 (medium) Phillips, and small- and medium-tip flat-blade drivers. Magnetic tips are handy, but not necessary. Be sure to purchase a good set. Test the grips for comfort. The plastic of the grip should not dig into your palm. Try soft (rubber) coated grips for extra comfort.

Hammer ¶ 

None of the designs in this book call for pounding nails into wood, but you might still use a hammer for tapping parts into alignment or for using a center punch to mark a spot for drilling a hole. A standard-size 16-oz claw hammer is perfect for the job, but a ball-peen hammer also works, as long as it's not too large. You don't want a sledgehammer when a gentle knock is all you need.

Pliers ¶ 

Pliers hold parts while you work with them. A pair each of standard and needle-nose pliers is enough for 94.5 percent of all jobs. Don't use either as a wrench for tightening nuts; they'll slip and round off the corner of the nut, making it harder to remove later on. Instead, use a nut driver, detailed below.

For heavy-duty applications, purchase a larger pair of needle-nose pliers. A set of "lineman's" pliers can be used for the big jobs, and they provide a sharp cutter for clipping nonhardened wire.

Hacksaw ¶ 

The hacksaw is the mainstay of robot body building. Look for a model that allows quick blade changes. Common blade sizes are 10" and 12" in length. The smaller blade length is recommended when working with metal. Purchase an assortment of carbide-tipped blades in 18 and 24 teeth per inch (referred to as tpi, or pitch).

By convention, hacksaw blades are inserted so that the teeth face forward. That means the saw cuts when you push the blade away from you. However, there is no strict rule about this. Experiment to see what works best for you.

Electric Drill ¶ 

You use a drill to make holes; an electric drill makes the whole hole process easier. Pick an electric motorized drill with a 1/4" or 3/8" chuck-the chuck is the part where the drill bit is inserted. Chuck size determines maximum diameter for the shank of the bit. The vast majority of work on small robots will require bits of 1/4" or smaller.

RoboTip!

Spring for an adjustable-speed, reversible drill. The slight added price is well worth it. Adjusting the speed is important when working with different kinds of materials, as some (like metal) need a slower tool.

Drill Bits ¶ 

A drill is what turns a bit; the bit is what actually makes the holes.

So, with that amazingly helpful clarification out of the way, let's get on with the advice: purchase a drill bit set in so-called jobber length. In the United States and other locations where they still use inches, drill bits are measured in fractional sizes. The typical fractional drill bit set contains 29 bits (give or take), in sizes from 1/16" to 1/2", in 64ths-of-an-inch steps. For most robotic creations, you'll use only a third of these, but it's nice to have the full set in case you ever need the others.

FYI!

Drill bits under 1/4" are also identified by their numerical size. For example, a #36 bit is the same as 7/64".

• The least expensive drill bits for robot building are made of high-carbon steel.

• Better drill bits are made with high-speed steel, and these keep their sharpness for longer. These are fine for most amateur robotics workshops.

• Tungsten carbide bits stay sharp the longest even when cutting metal. They're more expensive than the others.

• Cobalt bits are the Terminator of the bunch. They drill into most anything, including hardened steel.

Drill bits have different kinds of coatings, which extend their life. However, when coated, the bit usually can't be resharpened, as the resharpened edge will no longer have the coating. Black oxide coating is the least expensive of them all, and is useful for wood, soft plastic, and thin aluminum. Various titanium coatings greatly extend the life of your bits, allowing you to use them on thicker aluminum and steel.

RoboTip!

Save money! Get a standard fractional drill set in standard high-speed steel, then augment that set with specific sizes of more-expensive longer-lasting bits. The most commonly used bit in my shop is 1/8", so I get extras of those with a titanium coating.

Screwdriver Bits ¶ 

When you find you're doing a lot of screw assembly, invest a few dollars in a set of Phillips and flathead bits for use in drills and motorized driver tools. These fit into the drill chuck like any other bit but are used to tighten and untighten screws. To be useful, your drill needs a variable-speed motor; you'll surely strip out the screws if you try to use the bits at high speed.

Hobby Knife ¶ 

Hobby knives include the X-Acto brand, sporting interchangeable blades. They're ideal for cutting cardboard, foamboard, and thin plastics. A word of caution: The blades in these knives are extremely sharp. Use with care.

Nut Driver ¶ 

Nut drivers look like screwdrivers, but they're made to tighten hex-head (six-sided) nuts. They come in metric and imperial (inch) sizes. On the imperial front, common driver sizes are:

Driver/ For Hex Nut

1/4"/#4

5/16"/#6

11/32"/#8

3/8"/#10

7/16"/1/4"

1/2"/5/16"

Optional Tools ¶ 

There are a couple more tools that are nice to have but aren't absolutely critical to build a robot. Add them as your budget allows.

• Miter boxes help you make straight and angled cuts into tubing, bars, and other "lengthwise" material. Attach the miter box to your worktable.

• A vise holds parts while you drill, cut, or otherwise torment them. What size vise to get? One that's large enough for a 2" block of wood, metal, or plastic is about right.

• A drill press sits on your workbench or table. It helps you make smoother, more accurate holes. Lower the bit and drill the hole by turning a crank.

Hardware Supplies

A robot is about 70 percent hardware and 30 percent electronic and electromechanical components. Most of your trips for robot parts will be to the local hardware store. The following sections describe some common items you'll want to have around your shop.

SCREWS AND NUTS ¶ 

Screws and nuts are common fasteners used to keep things together. Screws (called bolts when they're bigger) and nuts come in various sizes, either in metric or in imperial (inch) units. For this book I stick with imperial sizes, because that's still what we use in the United States, and it's what I'm used to.

Anyway, here are the very basics of what you should have to build your robots.

• Use 4-40 size screws and nuts for the typical tabletop robot. The "4" means it's a #4 fastener; the "40" means there are 40 threads per inch. Screws come in various lengths, with 3/8", 1/2", and 3/4" being the most useful for small robotics. I use 4-40 x 1/2" screws the most.

• For bigger parts and bigger robots, use 6-32, 8-32, and 10-24 screws and nuts. The most commonly used screw lengths are 1/2", 3/4", 1", and 1-1/2". These and other sizes are available at any hardware or home improvement store, and you can pick up what you need when you need it.

• For very heavy duty work, you want 1/4"-20 or 5/16" hardware. (1/4"-20 means the screw is 1/4" in diameter and has 20 threads per inch; the standard for this size). Get these only when plans call for them.

Locking nuts are a special kind of nut you'll use a lot in robotics. They have a piece of nylon plastic built into them that provides a locking bite when they are threaded onto a screw.

Washers ¶ 

Washers are used with screws and nuts and help to spread out the pressure of the fastener. They're also used when you want to make sure the nut and screw don't come apart. The most common is the flat washer, which is typically used to keep the head of the screw (or the nut) from pulling through the material. Tooth and split lock washers apply pressure against a nut to keep it from coming loose.

Angle Brackets ¶ 

Also ideal for robot construction is an assortment of small steel or plastic brackets. These are used to join two parts together. They come in different sizes, the smaller sizes being perfect for use on desktop robots-smaller brackets weigh less. I often use 1-1/2" <mult> 3/8" flat corner steel brackets when joining two pieces cut at 45° angles to make a frame.