Derby Talk

Here's a very useful website for doing weight-to-volume calculations:

http://www.allmeasures.com/Formulae/

Specifically, this page will help you figure out your wood body will weigh:

http://www.allmeasures.com/Formulae/sta ... ensity.htm

Does anyone have a simple chart that shows typical denisties and volumes for materials likely to be used a weights.

I would think this would be a help in planning the design.

Thanks

Jthompson wrote:Does anyone have a simple chart that shows typical denisties and volumes for materials likely to be used a weights. Thanks

I've weighed over 50 PWD blocks. I've seen from 93 grams to over 140 grams!! You can feel the major difference the densities, even though they're all pine!! You'll have to weigh a few blocks and use the lightest one you can find.

Some densities (per SolidWorks): tungsten 19 g/cm3, steel 7.8 g/cm3, lead 11 g/cm3, brass 8.5 g/cm3, copper 8.9 g/cm3, aluminum 2.8 g/cm3, pine 0.34 g/cm3, oak 0.56 g/cm3, maple 0.49 g/cm3.

Your mileage may vary.

It might be worth noting that for what we gain by losing weight (using the lightest block) we give up by losing strength.

An Oakwood Derby Car would be considerably stronger than a Balsawood Derby Car. Some radical designs might benefit from the use of wood that is more dense especially if the design focuses weight where it becomes an advantage.

www.matweb.com is another great source for material properties. Density, etc.

Stephen's Dad wrote:It might be worth noting that for what we gain by losing weight (using the lightest block) we give up by losing strength.

I've also come to that conclusion. I've weighed nearly as many blocks as Pinewood Daddy and I get anywhere from 90 grams to 152 grams. In order to boost the strength on the lighter blocks (especially if there are going to be thin cuts to the design), I glue a piece of 1/8th inch hobby plywood to the bottom of the block. When I cut out my car the plywood makes a big difference in keeping the wood from cracking or splitting (especially along the grain).

-Nitro Dan