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The 12V Trail Drill
 

So there we were on the Cliff Hanger trail in Moab, enjoying the sites with those who had gotten together to participate in the 4th Annual Jeeps Unlimited Moab Run, 4AJUMR.  We had just gotten down to the creek crossing and one by one were climbing out.  Larry decided his line wasn't quite right so he slipped his TJ into reverse and started to back up a few feet.  His rear tire caught a rock just right and it flipped up and hit the yoke on his rear axle.  No problem except that it clipped the head of the bolt that holds the u-joint strap in place.  The thread locked bolt sheared off in the yoke with nothing protruding to get hold of.  While we had spare bolts, spare straps, and even a set of Easy Outs by which to extract the sheared bolt, we didn't have a drill to make a hole for the Easy Out.  DOH!  It was at that point that I promised myself that I would remedy that situation and be ready for the next time this happened.

After I returned home from Moab, I finally got around to e-mailing a note to the the local club members to inquire if anyone had any old 12V cordless drills laying around that they no longer wanted.  Given the more current 18V and 24V cordless models now available, it is not uncommon to find the older technology 12V drill sitting on the garage shelf, complete with a battery pack (or two) that will no longer hold a charge and/or a toasted battery charger.  I received a couple of responses and made provisions to pick them up.  What follows is my 12V trail drill project.  ScottK stopped by just before I started the project which was good news for me as that gave me someone else to blame if things didn't go quite right! 


The only purpose of this drill is to sit in the storage box for however many months/years are necessary until it is needed for a trail fix.  As such, relying on a rechargeable battery for power was NOT in the plan.  I had no intentions of baby sitting a Ni-Cd battery pack so that the drill would work when it was needed.  Scott and I discussed various ways by which to turn this 12V cordless drill into a 12V corded drill.  Although it was possible to gut the bad battery pack and use the shell to attach the 12V power cord to the drill, it sucked up good storage space which is always at a premium.  We decided to ditch the battery pack completely and attach our 12V power cord directly to the drill body itself.  A hacksaw and a few strokes took care of the battery pack mounting flange on the drill.




With a couple of female spade lug clips crimped onto the end of the 12V power cord, I managed to slip them onto the existing power terminals that would normally make contact with the battery pack...yeah, this was our plan.  However, I was not satisfied with the fit...or I guess I should say the lack of a good connection that this configuration provided.  OK...scrap this idea....."Scott, I told you this wasn't going to work!"
 


A half dozen screws later, we had the drill's plastic case apart and I was identifying the red and black power leads that connected the battery pack's terminal block to the speed control.  Using a soldering iron, heat shrink tubing, and some electrical tape, the 12V power cord was connected to the drill's speed control.
 


The two case halves were reassembled and the screws replaced.  There was a good sized gap in the case where the power connector block had been.  We took some plastic wrap and wadded it up into a couple of tight pieces and then packed it around the 12V power cord.  We were going to put RTV in the bottom of the drill handle to seal things up and act as a stress relief for the 12V power cord.  However, most (all?) RTV is not copper wire friendly (it will corrode it) and the warning label on the tube I had clearly stated this.  The plastic wrap would serve as a barrier between the end of the handle where the RTV would be put and the inner workings of the handle where the speed control (and copper wires) were located. 
 


The last step was putting the RTV into the handle's void.  As I write this, the RTV is still curing.  At this time, I'll probably be stopping by the local Radio Shack store to pick up a pair of small battery clamps and I will be replacing the cigarette lighter plug at the other end of the 12V power cord.  While plugging the cord into an empty lighter socket is certainly handy, the intent is that this drill can be used on any vehicle and powered by that vehicle's battery.  If the vehicle's lighter socket is bad (not an uncommon situation), the drill won't work.  By using small battery clips to power the drill directly from the vehicle's battery, the possibility of a malfunctioning lighter socket is eliminated.  I'll include an in-line fuse holder near the positive battery clip to guard against any possible melt downs if the drill faults or the power cord is damaged.

There are, no doubt, other methods by which this project could have been done.  This one turned out pretty good, in my opinion, in spite of the bad ideas that Scott kept coming up with.  <grin>  If you decide to add a 12V trail drill to your inventory, drop me an e-mail with a couple of pics so I can see how yours turned out.


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