Introduction: Auto-Based 12 Volt Expeditionary Rotary Hole-Maker
If you're anything like me, you spend a good portion of your time living out of your truck, DOWN BY THE RIVER! Well then, I don't need to tell you how many times I wish I had a drill for one reason or another. Sure, you could get a cordless drill, battery charger, and converter. But that's stupid! Wouldn't it be better to have a straight 12 volt drill that doesn't need recharging? Of course it would! And that's where I come in. There are a couple similar approaches here on Instructables, but nothing that addressed my needs exactly or, frankly, as elegantly as this little jewel. The project turned out much better than I hoped, so I see it as the first in a series. Eventually, I'd like to have a direct 12v circular saw and reciprocating saw. Okay, then, let's kick this mule!
Step 1: Bring Out Your Dead (Drill)!
You see these at thrift shops by the boatload: poor, lifeless, cordless, batteryless drills. Skil, Ryobi, DeWalt, Makita, Milwaukee. Piles and piles of them. They come in all shapes, sizes, and colors. 9.5 volt, 12 volt, 18 volt, 19.2 volt, 28 volt lithium ion cadmium isotropic Cadbury bunny eggs. Their said story is written across their hollow bases: their crappy, proprietary, obsolete-inside-of-a-week batteries gave up the ghost and it was easier -- nay, necessary! -- to toss them aside and buy a new drill. So they end up at your Goodwill; your Savers; your St. Vincent de Paul's. Maybe some bloke's got a fully-functioning, Makita brand, model MK56729L-08, 9.5-volt CI battery, with charger, but no drill for it. Uh, yeah, right. So these lost children sit on the shelf, gathering dust until the thrift shop manager finally shovels them into the dumpster. What we need is a 12-volt model. Who cares about the rest of that crap? Here's the one I got for $3.00. I could have waited for half-off day, but what the hell.
Step 2: De-Exoskeletonization
Start by removing the obvious (and less than obvious) screws that hold the drill body together. The screws in mine were Torx T10s and odds are yours will be something just as annoyingly obscure. They came out pretty easily, for the most part. A couple were recessed deeply and my Torx bit wouldn't fit down far enough so I "enhanced" the approach hole a bit with another cordless drill that I have yet to drop off at Goodwill.
Step 3: Check Out Them Guts!
Once all the screws were out, I could lift off the one side of the casing, revealing the drill's innards. I'm not very mechanically oriented and have trouble differentiating between electronics and electrolytes. Nevertheless, this seemed pretty straightforward. There were two metal prongs jutting downward, into the battery well. One was marked "B+" and the other "B-". I assume the "B" stands for battery and the +/- signs indicate positive and negative. I've been wrong before. These prongs go into a black thing, that is connected by some wires to a round thing. There's a gear on the end of that, which fits up to another black thing that goes out and holds your drill bit. See? Like I said, pretty straightforward.
Step 4: From "Competition" Grips to "Combat" Grips
I got to thinking that the case looked kind of stupid, what with the big battery flanges at the bottom. So I cut them off. Problem solved.
Step 5: Wiring
I broke down and got a pair of $10 jumper cables from Harbor Freight. I cut these in half, so I'll be able to use the other half down the road. After cutting the cables, I stripped 1-1/2" of insulation off each of the wires.
Step 6: Making Connections
The "B+" and "B-" prongs were oddly shaped, as you can see in the picture. I don't really know how to describe them and I don't particularly want to try. Yours will probably be different anyway. To make mine work best, I folded the stripped cable wires in half. They then slid into the weird prong end thingies. For consistency, I attached the red wire to the "B+" terminal and the black wire to the "B-" terminal. I suppose a "professional" would have soldered the wires to the prongs, but I don't happen to have some fancy soldering machine. What I did have, though, was a couple zip-ties, which seemed to do the trick. Then I used about 3/4 of a roll of electrical tape, making sure to cover all metal parts, keeping the two terminals apart. Once the two terminal/wire connections were adequately insulated, I taped around everything to prevent movement.
Step 7: Reassembly
Things are pretty anticlimactic from here on out. I shoved all those parts back into the modified case and screwed it shut. The jumper cables exit through the old battery compartment. I thought that looked a little unprofessional, so I used the rest of my electrical tape to create a seamless transition from handle to cord. Now it looks pretty much like a sci-fi death ray laser gun or something. But don't let the looks fool you, it's really just a drill. Not, not just a drill, a bad-ass, off-road, adventure-seeking, alpha drill! Now when some un-holey nightmare threatens to derail your camping trip, you just pop the hood, clamp the cables onto your old Optima yellow-top, and get to perforating! You're welcome.