My two children are currently in Cub Scouts and participate in the annual pinewood derby which leaves me to stumble through trying to help make their cars.
I have strong memories of building cars with my father. My cars were consistently some of the best in the pack so my room had several resulting trophies (at least one first place). My father had a nice woodworking setup in our basement and corresponding experience, though my primary memory is spending what felt like a long time sanding and using hand tools after which he'd use power tools to have far more effect in far less time. Things have also changed significantly since then as information on the Internet and a cottage industry for gear have led to cars which would likely leave the cars I had made in the dust.
At the moment I don't have much of a workshop at all, and instead have a pile of unsorted inherited equipment with little supporting knowledge and a small corner of my basement somewhat cleared out. I generally want to make sure my children are more active participants than I likely was, and I also don't want to lean on specialized equipment since that seems to me to possibly invlalidate the original spirit of the pinewood derby and also goes against some of my minimalist ideology. For making the cars in general it seems as though hand tools should mostly be sufficient and more accessible for children, with the exception of drilling since hand drilling is a pain (I may pursue this for some other projects, but for this it would just be a recipe in frustration. I do however purchase some more tailored supplies such as weights.
This page acts to capture some of my discoveries and progress year to year in the hopes to improve over time. Last year was the first year with only a single car and my primary goal was that the car would make it down the track in one piece. It performed just above average - enough to make it into the finals and then pretty much lose every race there. The car itself was cut and then weights were mostly just plopped on top in mount of tungesten putty. My son only wanted to color it with markers so it certainly didn't look particularly good. Looking at the car this year I also noticed that while the axles were bent, the bend did not seem to be enough to leave the wheels properly cambered.
This year unforutnately the flu worked its way through my family right before the derby, and so preparation was delayed and then squeezed in to the week days prior to the race.
Cutting the cars was done with a hack saw, particularly given the child participation some of the cuts ended up less than straight (not that I'm adept at straight cuts) and so I'll probably look at picking up a mitre box for next year.
Both cars were current with very little height which left both less weight and less space in which to inconspicuously add weight. For one of the cars I drilled out a hole using the largest drill bit I had on hand...I have some larger hole cutters but I couldn't quickly find them and they may have needed more depth to work effectively regardless. I then ended up using a hammer and chisel to widen the hole to a rectangle large enough to hold enough weight (weights and putty) and deep enough so that the result was fairly flush. For the other car I drilled out three 3/8" holes which are the right size for stacks of weights and added weights along with some putty to those holes along with some weighted tape which was cut roughly in half and stacked on top of itself.
I quickly attempted to smooth out the wheels using sandpaper and a drill, this is something that I'll probably look at paying closer attention to next year as I didn't use some of the additional supplies which are sometimes mentioned, and I had mixed luck in making sure the wheels were held tight enought to rotate.
Polishing the axles is something I did last year with unclear benefit. Similar to the above I may want to get some actual polish, but this year I'll do the same tehnique I did last year of clamping the drill and taping the trigger, and then using sandpaper against the axles. Last year I think I just used dry sandpaper but this year I'm doing wet sanding based on advice found on the interwebs, with a ladder of 1500, 2500, and 3000 grit since that's what I readily found for fairly fine papers.
This year I improved the process a bit by noticing a nearby strap wrench that I'd acquired at some point over the years, which provided a far more efficient route than the tape - simply tightening and loosening the wrench to turn the drill on and off respectively. I also luckily found a file nearby which I could use to smooth out the head, and I added a couple steps of 600 and 800 grit dry sanding before the wet...I'm not sure whether this had impact (most of this is pretty speculative without some kind of metric) but I added this additional step when noticing some of the remaining marks on the axle...but those marks still remained after doing ten seconds each of filing the head, the shaft, and using each of the five papers. After doing that for the eight axles I'm pretty much out of time regardless.
In the derby both cars did better than the previous year, though there was a significant difference between the two. One ended up winning third in the pack - performing where it was comfortably faster than most of the cars but the fastest cars were comfortably faster than it (so it will likely end up in the middle of the pack in the regional competition)...the other car won a couple races but as much due to the luck of the draw than speed. My guess is that the slower car had its weight slightly too far to the back of the car. One clear takeaway from me is the notion that I should not only spend more time but also have a means to test the speed of the cars, when testing for alignment/rail riding the car that ended up being slower seemed faster and so I could certainly use some means to more accurate gauge how the cars will perform.