Pinewood Derby car imitating a bench plane.

Plane Car

Here’s my finished plane car. I kinda like it. I went to Lowes tonight and bought a three-foot chunk of 1/4″x1″ slab of steel. I did some calculations and found that it was going to be very difficult for me to drill holes in this thing and fill them with lead to get the weight up to 5 oz (aka 141 grams). I weighed it first, and it came in at 52 grams. That’s a wee bit on the light side. If I drilled a quarter inch hole into the sole and up through the rear grip, it would have to have been something like 7 inches deep so that when filled with lead, it would add another 90 grams. A half inch hole was more like it, but the handle isn’t a half inch wide, so the tolerances aren’t just tight – they’re impossible. So I turned to the next strategy which was to replace the wooden blade with a steel one. a quarter inch thick blade one inch wide would need to be just under 3 inches to weigh in at 90 grams. And yes, I love converting between metric and English. Not.

Thus the trip to Lowes for a slab of steel. I ground an edge onto the end, and then measured off three inches. I cut it a little short, but that’s OK, because I had forgotten to weigh the thing with the wheels and axles first, so everything will be off anyhow. Then I tapered the top end and sanded the black junk off the steel. And of course this gets more ridiculous, because then I put it in my sharpening jig and zipped it over my 1000 grit stone. I refrained from using the other side of the stone which is 6000 grit. No need for that much overkill!

Once I was happy with my blade of steel, I glued it on. I couldn’t find my bottle of Gorilla glue, so I just used Elmers School glue. I am almost certain to regret that, but it is what it is. I really need to reweigh the whole shooting match now just to make sure I’m under 141 grams, but our balance only has 100 grams of weight! To get semi-close though, I filled a cup (with non-zero mass) with about 140ml of water (eye-balling the line between 125ml and 150ml). That should be pretty close to 141 grams, and it was heavier than the plane car. But we’ll see. I ought to bring my drill and a bit along in case I need to drill a hole in the blade to reduce the weight. Or just say “forget it” because this car is really not built for speed anyhow. I’m hoping to win the in the “style” department.