Technical Difficulties from on Top of the Mountain
2005-04-03
  The bicycle
Max is getting to the age where he's ready to go mobile and because of our backwoods location, there aren't too many sidewalks conveniently located for riding smaller hot-wheels type vehicles. So I started thinking along the lines of a real bike.

Due to a random fluke, I was over on the other side of town with some minutes to kill; so I popped into the nearby Salvation Army to see if there was anything interesting in the bins. Nothing grabbed my attention, so I wandered into the back, where behind a row of pressboard shelves and steel office furnature from the 1950s, I discovered a row of bikes, from adult size all the way down to just-starting-out size. The price seemed right too: $5. So I grabbed one from the end, and checked out, very pleased with myself.

Max was pleased as well, though there was still some work to be done. None of the bikes had training wheels, so something would have to be arranged. Also, on closer inspection, the back tire had been worn clean through and the innertube was flat. So there was some fixing to be done.

bicycle tire

After some misdirection, looking for a wheel size that does not exist (how I got 10" in my head instead of 12" I'll never know), I had a new tire and a patch kit. Back in the old days, patching a tire took some real skill. I never had to use the 'melt-it-on' style, but we still had to cut out our patches from some square stock, prep the area, apply the glue, and press the whole thing together until it set. Now the entire kit is a couple plastic bars for prying off the tire and a sheet of stickers. Kind of takes the mystery out when a three year old can do it.

So with the tire fixed, it was time to think about some outriggers. Once again the internet turns out to be pretty worthless, as shipping for a set of wheels is more than the wheels themselves. Guess its all that steel and bulkiness. The local bikeshops weren't much help either, as new bikes generally come with a set. Special ordering something for $20 that usually comes for free with a $40 bike didn't sound very good. Time to come up with Plan C.

A few years ago, my only option would be to scrounge around, asking other parents for leftovers; but now thanks to hundreds of hours of professional training at the local community college, I had a little knowledge of metal fabrication. And as we all know, a little knowledge is a dangerous thing.

After picking up some wheels at the local hardware store, I set off to the metalshop to concoct my solution.

It started off pretty straightforward. The ironworker was able to turn a four inch wide strip of quarter inch plate into two two inch wide strips with one quick chomp, then put some holes in the ends with another chomp (of the punch end), and then after moving the press brake into place, I had put two 90° bends into each piece. So far, so good.

The next part to do was the axle for the wheel. The plan was to find some half inch bar stock, weld one end to the bent strip, and drill a hole for a cotter pin in the other end. It sounded like a good plan except for the fact that there was no half inch bar stock in the metal pile (school stockrooms are often annoying that way).

Well, there was some 5/8 stock and a full machine shop. A lathe is especially good at making a large round thing into a smaller round thing, so onto the lathe. One has to be especially careful with school machines when following the readings on the dials. One would think that turning the crank in 0.005" would reduce the diameter 0.01", but its just as like to reduce it 0.015" on the machine thanks to the hundreds of impatient highscool students who have come before. Luckily I've learned never to take anything for granted, so I hit my target just right. With a final polish pass using some 120 grit sandpaper, I had a nice & shiny axle and I was just about ready.

The last hard step was putting a hole in the end for the cotter pin. Here the taper in the bar stock (I only milled down the end for the wheel) helped, as I was able to fit the rod through the plate, add a washer on the back, the wheel, and then a washer in the front, and measure where the pin hole would need to be. Unfortunately, drilling a small hole in the side of a hard round object is rather difficult, and the drill kept wanting to swerve off to the side, but after some adjustments and a couple of attempts, we managed to get a hole drilled (though not in the center exactly) and the fine work was all done. Taking all the pieces home, I finished assembly with my own MIG 200 welder which did a nice job joining the two thick pieces

So after putting it altogether, we took it for a spin. Everything seems to work great at this point, though the outriggers are so strong and large (I was really aiming at building a trike for starters), that occasionally Max rides over a rut and the back tire starts free-wheeling, but I'm sure he'll figure it out. The bars should be strong enough that his little brother could stand on them and ride behind once Max gets his peddling strength up. And I'm sure someday down the road when he no longer needs training wheels, those wheels will see use in some other project.

Was it worth it? If you just look at the costs of the parts and time vs the cost of a new bike, probably not. But there's non-tangibles that balance it out. For one, Max got to learn that getting something doesn't always mean going to the store and buying it. Sometimes to get what you want, you have to make it, and that takes time and effort. I also got a good review on the iron-worker, the lathe and the mill; as well as having something else I was able to weld with my welder, which was all good. To paraphrase "throw mama from the train": a metal fabricator fabricates–always.

 
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