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The Vice-Prez Sez

Karl Lunt

The latest Robothon, held Saturday, 17 May 1997, was a great hit and drew a crowd of over 100 humans and about 40 robots. Glad to see such a good turnout and my thanks to all who made it such a successful event. A special "Thank you" to Kevin Ross, who put in so many long hours of legwork and preparation.

Seeing all of the robots brought home once again how important a well-stocked junk box is to this hobby. If you do only electronics, you need a big junk box. If you do only mechanics or machining, you need an even bigger junk box. If you do only software, your room usually looks like a junk box. But if you really want to succeed at robotics, you have to have a BIG junk box.

As a case in point, consider the little project Marvin Green and I worked on after getting back to my place from Robothon. We had stopped at VETCO and picked up some of these neat pale-blue ABS project boxes. I wanted to put wheels on one and turn it into a robot base (what else).

We decided to use a friction drive, rather than the standard hobby servos. So we rooted through my junk box to find a couple of high-efficiency motors from defunct cassette drives. I also found some cool hobby airplane wheels in the old JB. These happened to have 3/32" bores, so they slip-fitted onto some brass rod I scrounged from the JB.

I cut the brass rod to about a two-inch length and clamped it in my bench vise. I then used pliers to twist a 4-40 nut onto one end of the rod. The steel nut cut threads into the rod, but didn't make the clean cut that a real die would have made. Instead, it left a very tight fit that wouldn't back off or need any extra hardware to stay in place.

I then slid a wheel down the other end of the brass rod, then added a small brass rivet, left in my JB from my many hobby servo purchases. I used the old 100 watt Weller soldering gun to solder the rivet onto the brass rod, acting as a retainer to hold the wheel in place.

I then drilled a 1/8th-inch hole in the project box at the proper location to hold the axle, then slid the long portion of the axle into the hole and held it in place with foam tape and hot glue. I also drilled the proper holes immediately above the wheel so the cassette motor shaft would press against the wheel's surface. I had to dink around a little to get the fit just right, but a Dremel tool and milling bit works wonders.

After only about an hour of work, Marvin and I had two wheels and two motors mounted on the project box. We added some batteries and a steel furniture foot (for a front caster) and the little box was scooting around the floor.

Of course, I'm ready to tear it all apart and do it over, since I've figured out a better way already. But the point is that with a large junk box to draw on, Marvin and I could simply sit down and create. If we needed a tool or some type of material, it was within reach. We spent our time building, not driving.

I'll warn you, however, that building up such a large and serviceable junk box takes time and dedication. Such a huge resource doesn't appear overnight. You have to spend many hours and mucho bucks at VETCO, Active Electronics, and the best mail-order houses to create a top-notch stock pile.

And don't be tempted, as the years go by, to toss something just because you haven't used it yet. I bought the motors we used on this base over five years ago, kept them faithfully, and had them ready when they were needed. Ditto on raw materials; after all, brass rod doesn't evaporate, and you never know when it will be the exact item you need for that Sunday afternoon project.

I realize that storing such a large inventory can take up quite a bit of room, so I advise you to move early and often. Linda and I just finished moving to a new house, and suddenly I have LOTS of room for my junk box. You should do the same, whenever it looks like you don't have room for even one more surplus parking meter or microfiche machine.

So now I hope you see the importance of having a well-stocked junk box. If your spouse doesn't understand this yet, leave a copy of this article laying around in plain view; I'm sure you'll get a reaction.


Here's a tip for those of you who have a lot of neat motors in your junk box, but you can't get the neat but useless metal gear or pulley off the shaft. Use your 100-watt Weller to heat the heck out of the pulley, then real quick use pliers to give the pulley a yank. It will usually pull off the shaft after a good heating. After all, these are press-fit onto the shafts; heat them up and they will expand just enough to loosen up.

Keep on keeping on...