Page 148 - Robot Builder's Bonanza

THE METALSMITH’S ART 117

Figure 11-8 By using pillars (also called
risers or columns), you can literally stack
frames together to make boxlike body
shapes for your robots.

2. Drill corresponding holes at the approximate center of each side of the frame. (See
“Drilling Metal,” next section.)
3. Assemble, using 4-40 1/2″ machine screws and nuts. Use flat washers on the
screw- head side.

When building large frames— say, over 14″ square— use two pillars per side; that means
eight total. Position each pillar about 1″ to 2″ from the corners of each frame. This gives you
room in the middle of the box to work.

DRILLING METAL

Metal requires a slow drilling speed. That means, when using a drill, you should set it to no
more than about 25 percent of full speed. Variable- speed power drills are available for under
$30 these days, and they’re a good investment. Use only sharp drill bits. If your bits are dull,
replace them or have them sharpened. Quite often, buying a new set is cheaper than profes-
sional resharpening. It’s up to you.

Punching a Starter Hole
You’ll find that when you cut metal, the bit will skate over the surface until the hole is started.
You can eliminate this skating by using a center punch tool prior to drilling. (In a pinch, a nail
works, too.) Use a hammer to gently tap a small indentation into the metal with the punch.

Dabbing On Some Oil
When drilling aluminum thicker than 1/16″, or most any thickness of steel, first add a drop of
oil over the spot for the hole. If you’re drilling a very thick piece, you may need to stop periodi-
cally and add more oil. There’s no rule of thumb, but one drop per 1/16″ or 3/32″ of thickness
seems about right. The purpose of the oil is to keep the bit cool, which makes it last longer.

Using a Drill Press
When it comes to working with metal, particularly channel and pipe stock, a drill press is a
godsend. It improves accuracy, and you’ll find the work goes much faster.
Always use a proper vise when working with a drill press. Never hold the work with your
hands. Especially with metal, the bit can snag as it’s drilling and yank the piece out of your
hands. For best results the vise should be physically attached to the base of the drill press.
Anchoring the vise may not be critical if it’s heavy, and it will hold the pieces you drill in place
just by its sheer weight.
If you can’t place the work in the vise, use a pair of Vise- Grips or other suitable locking
pliers. The pliers allow you to adjust the jaw size and “lock down” on the material for a sure

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