If you've just cracked open your official BSA kit, the very first thing you'll probably notice is the particular specific dimensions of pinewood derby block that a person have to work with. It appears like a simple chunk of wooden, but that rectangle-shaped piece of pine may be the foundation with regard to everything you're about to build. Whether you're a search trying to win the trophy with regard to speed or the parent just wishing the car makes it to the finish line without shedding a wheel, understanding these measurements will be step one.
Most people see the block and instantly think about what they wish to cut aside, but it's really essential to know what you can't change. The track has really specific physical limitations, and if your own car winds up too wide, too long, or even too low, it simply won't run. Let's break lower what you're in fact looking at when you pull that wood out of the box.
The normal Measurements You'll Find in the Container
A regular official BSA pinewood derby block generally measures 7 inches long, 1. 75 ins wide, and 1. 25 inches high . It sounds fairly straightforward, but these numbers are actually quite intentional. The 7-inch length will be the optimum allowed in many events, though you'll usually see people trim a tiny little bit off the back again or front to accommodate specialized bumpers or weight storage compartments.
The thickness is arguably the most critical dimension. At 1. 75 inches, the block is designed to sit perfectly on the track with no rubbing against the particular side rails too significantly. If you determine to narrow the particular body for the "needle" style vehicle, you have to be careful. A person still need sufficient wood at the axle points to keep the wheels spaced properly. If the wheels are too close up together, the car may straddle the middle railroad and grind to a halt.
Then you've obtained the height. In 1. 25 ins, the block offers you enough "meat" to carve out a wedge, a smooth sports car, or also something goofy like a hot canine or a college bus. Most speed-focused builders end upward cutting away the massive chunk of this height to lower the center of gravity, often leaving behind the car only about half an inch thick at its tallest point.
Why Those Accurate Inches Matter
You might wonder why we're being so picky in regards to a piece of pinus radiata. Well, the monitor itself is the fixed environment. Most pinewood derby tracks possess a center guidebook rail that's about 1. 625 ins wide. Since your own block starts from 1. 75 inches wide, you might have simply enough clearance to match the wheels on the outside while the body of the vehicle clears that center rail.
If you mess with the dimensions of pinewood derby block without the plan, you operate into "clearance" problems. For example, the distance between bottom of the car and the track surface area (the "ground clearance") needs to be at least zero. 375 inches (3/8"). If you include weights to the bottom of the particular car and they will stand out too much, the car will certainly scrape against the particular center rail. Nothing at all kills speed faster than friction, and nothing creates rubbing faster than a car dragging the belly throughout the monitor.
Dealing with the Axle Slots
If you glance at the bottom of the block, you'll observe two grooves cut into the wooden. They are the axle slots. In the standard kit, these types of are usually spread about 4. twenty five inches apart. This particular "wheelbase" is the huge factor in exactly how the car holders.
Some scouts like to exercise new holes instead of using the particular slots to ensure the axles are perfectly right. However, many competition rules require you to make use of the original slots. If you're allowed to move them, individuals often extend the particular wheelbase (moving the particular wheels further toward the ends of the car) to make the car more steady. But even then, you have in order to respect the overall dimensions of pinewood derby block rules—the wheels can't stick out past the particular front or back again of the 7-inch limit.
It's also worth noting how the slots aren't always perfectly square from the factory. I've seen plenty of kits where 1 slot is somewhat crooked. Checking this particular before you begin carving is a lifesaver. In case the slots are crooked, your car will "dog-track" (drive sideways) and strike the rails constantly.
Weight Distribution as well as the Remaining Wood
While the exterior dimensions are usually fixed, what you are along with the internal volume of that wood is where the wonder happens. The particular goal is almost always to achieve exactly 5 oz. A raw block of pine usually weighs somewhere close to 3. 5 in order to 4 ounces depending on its moisture content, but when you start cutting it into a cool form, that weight drops significantly.
Because you're removing so much wood, you need to include weight back in—usually in the type of tungsten or even lead. Knowing the particular dimensions of pinewood derby block can help you figure away where that weight can go. Most benefits want the middle of gravity to be about 1/2 inch to 1 inches in front of the rear axle. This means you require enough wood thickness in the back of the vehicle to drill holes for your weights with out snapping the vehicle in half.
If you shave the car down in order to a paper-thin sliver, you won't have anywhere to hide the weight. I've noticed some really cool-looking "wafer" cars that ended up being incredibly fragile since the builder forgot they needed a place to place the tungsten.
Techniques for Cutting Your Block Without Damaging It
Prior to you have a found to the wood, grab a pen and a leader. It sounds old-school, although drawing your style quietly and the top of the particular block first is definitely the only way to stay within the lines.
- Don't thin the axle area: Keep the full 1. 75-inch width where the axles go ahead. This provides stability and keeps the particular wheels from massaging your body.
- Watch the nose: Most tracks have a starting pin that drops right down to begin the race. In case you make the particular nose of your car too high or even too pointy, it might not sit down right against the particular pin, or this might get caught when the pin drops.
- Leave some "meat" for the axles: In the event that you cut the block too thin vertically at the factors where the axles go ahead, the wood might split whenever you attempt to push the nails within. You want a minimum of a quarter-inch of solid wood over the axle slot machine if at all possible.
Guidelines and Tech Examinations
Every competition includes a "tech inspection" where someone along with a specialized package or a collection of calipers investigations your car. They're checking to make sure you didn't exceed the maximum dimensions of pinewood derby block limits. Usually, the car needs to suit inside a box that is two. 75 inches broad (including the wheels) and 7 ins long.
In case your car is 7 and 1/16th inches long mainly because you added a fancy plastic vender on the back again, you're going in order to be in the particular parking lot having a hacksaw five a few minutes before the race starts. It's way better to build slightly under the maximum dimensions in order to try and push it to the particular absolute limit and get disqualified.
Wrapping it Upward
At the end of the afternoon, the dimensions of pinewood derby block are there to give everyone a fair starting place. It's a standard canvas for a really creative project. Once you understand that the 7" x one. 75" x 1. 25" box is definitely your playground, you can begin focusing on the particular things that can even make the car fast—like wheel alignment, rubbing reduction, and weight placement.
Don't be afraid to get creative with all the shape, but always keep the ruler handy. A car that seems like a lightning bolt but is as well wide for the track is really an extremely pretty paperweight. Stick to the dimensions, leave enough wooden to back up your axle assemblies, and you'll be in great form when race day rolls around.