Basic Guidelines for Pinewood Derby Car Design
The possibilities are endless when it comes to picking a shape for your Pinewood Derby car. Before you begin, consider the following general guidelines:
Avoid designs with a pointed nose. A pointed nose will make it difficult for your Pinewood Derby car to rest on the pin at the starting gate. It may also cause your Pinewood Derby car to get bumped around when the pin drops, and it can create problems for electronic timing systems.
Leave enough wood in the rear of the Pinewood Derby car so you can place additional weight there. You will end up placing most of the weight in the rear of the Pinewood Derby car.
Make the maximum weight. Your car should weigh as much as it’s allowed. In most races, a Pinewood Derby car’s weight is limited to 5 ounces. If your car weighs less than that, add coins or other weights.
Be sure that it is very clear which end of your Pinewood Derby car is the front and which end is the back. In many races, the race officials —- not you -— will actually place each Pinewood Derby car on the track. Sometimes the officials put the Pinewood Derby car on the track backward because they can’t tell which end is which.
Choose a design that allows the air to move over and around the Pinewood Derby car body in a smooth manner. Pinewood Derby cars with aerodynamic profiles go faster.
Follow this article for the secrets to the ultimate Pinewood Derby car.
Post by ExtremePWD » Mon Dec 29, 2003 9:47 pm We baked 5 blocks this year at around 230 degrees and checked weight periodically. In 1.5-2 hours the mass was reduced by 6 grams on average. We flipped the blocks 1/2 way through. My Tigers “thin” car body was 8g (0.28 oz) before sanding. The lead was attached prior to final sanding so I can only estimate the final wood mass based on the ratio of thickness before to thickness after. The final mass is estimated at 6 g (0.21 oz).
Post by Scoremaker » Mon Dec 29, 2003 8:06 pm The intent of this step is to remove fluid weight from the wood block, thus allowing the additio of more lead at the rear of the car.If the wood block has been properly dried,or if the you live in a dry climate,baking the wood block will have virually no affect on the weight of the block.However,if you love in a damp climate ,this step might be useful,If you choose to bake the block,put the wood block on a middle rack,set the oven temperature to 325,and bake for 2-4 hours before you do any work on the body. By Randy Davis
Post by MaxV » Tue Dec 30, 2003 9:12 am The difference in wood density is mainly from the location within the tree from which the wood came. The denser wood comes from the heartwood, that is the inner portion of the tree. The lighter wood comes from the sapwood, which is the outer portion. Of course wood also varies from tree to tree depending on the speed at which the trees grew, and other factors. The heartwood is definitely harder, and I would guess stronger. But I dont know that for sure.
Post by PWD » Mon Dec 29, 2003 9:43 pm Our car is under 1/2 ounce after cutting. We use to bake the block but as Stan, I think, is pointing out that after the cut and you are already down to 1/2 ounce it really adds little value. Baking can make a difference with a 5 ounce block but not much difference with a .5 ounce block. The block right out of the box can differ signficantly in initial weight. One of our blocks last year felt more like a brick than a block of wood. Something was wrong with it so we did not use. I planned on bringing back this year but never did so still have the heavy block. BTW, I really question how much advantage it really is to drop the weight much less than 1/2 an ounce. Yes you can control the placement of the weight a little better but the difference is going to be very insignficant. -Stev-
Post by Da Graphite Kid » Tue Dec 30, 2003 1:17 pm Stan, since we are located in the steamy South, I had the same thought: dry the wood of your pwd car out just prior to final assembly of the axles and wheels, place it in a airtight container along with some desiccant packs (those little packs that say “DO NOT EAT!” on them) and that keep sealed items dry, than bring it to the race. I check in was fast enough and all your calculations were correct, you would check in a car that was near or just under 5.0 ounces. Ideally you would be first in line so that your pwd car could sit for a longer period of time to soak up moisture (and weight!). Since the weight of a pwd car is usually the biggest issue at the races I have been to so far, this is always checked first. Boy, those sweaty palms are going to pay off big time this year as I hand my sons car from inspection person the inspection person! This would all go well and unnoticed unless your pwd car had to be re-weighed for some reason during or after the race. Some design factors would be: – Paint your car or not? Not painting it would allow more surface area to absorb the moisture from the air. – The amount of pineblock needed after shaping your pwd car. You would need enough wood to be able to absorb enough water to make a difference. Looking at what others have reported: 6 to 14 grams difference when a pineblock was baked. That’s 0.2 to 0.5 ounces (I rounded) lighter when a whole pinewood block was baked. Now how many of us race the whole block? If we did, we wouldn’t be able to add all of the weight that we do now. For worse case here, you would need to have 1/2 of the original pineblock left after shaping your car to get a 1/10 ounce weight gain from moisture. For a best case, you would need only 1/5 of the original pineblock. I’ve weighed some pineblocks in the past and found my measurements fell within the 3.5 to 4.4 ounces that ExtremePWD found. That means that your shaped pineblock would need to weigh anywhere from 0.7 to 2.2 ounces (best case vs. worse case). We have built pwd cars that weighed anywhere from 0.5 to 1.00 ounces after shaping and painting (no added weigh or wheels/axles), so I know that in theory that this is possible due to block weight. Is this worth further consideration? I don’t think so, as there are too many variables to contend with: – Wood density. – The humidity percentage where you will be racing. – The timing issue between checking the car in for inspection and it being weighed. – The additional timing issue allowing your pwd car to soak up enough moisture to make a difference. Now, would this a rules violation? Unethical? or just good strategy? Da Graphite Kid
FAQ
How long should I bake my pinewood derby car?
How do I make my pinewood derby car straight?
- Bake your block. …
- Max out your weight at the regulation 5 ounces. …
- Use all of the graphite (dry lubricant is usually allowed). …
- Sand and polish your wheels and axles. …
- Check alignment. …
- Spend time on sanding. …
- Use a high-quality paint. …
- Add decals!