Rukkian wrote:No worries, it was an interesting topic. As far as offering free weights to everybody, maybe offering a cheaper weight would be fine, but the bar weights can get pricey, especially for a pack with limited funds (we serve a fairly low-income area). What is the cheapest way to offer weight - Pennies, washers? Are there other weights readily available?
Steel is easy to find and it is relatively cheap. Brass is denser, but tends to be more expensive per ounce because it contains copper. U.S. dimes and quarters are about as dense as brass because they are mostly copper inside. To make, say, 3.5 ounces of brass ballast, you would need about the same amount of metal that is in eighteen (18) U.S. quarter dollars or forty-four (44) U.S. dimes. Now, pennies made since 1982 are actually 98% zinc. To reach 3.5 ounces, you would need about 32 copper pennies (made before 1982), or 39 zinc pennies (made after 1982).
IMO pennies may be the cheapest form of weight ounce per ounce, but if you collect 39 new pennies (or 44 dimes, or 18 quarters), then ask yourself how you might attach that much metal to an existing car design, you should discover that it may not be very practical to use zinc, steel, brass, or cupro-nickel as ballast on a finished, unweighted car because it can take up a lot of space.
This is why I
suggested lead tackle - it takes up half the space of zinc. We are able to get lead fishing weights from the local Walmart. Also, as
Darin noted, depending on where you live, scrap lead can usually be found around tire service centers (ugly but
free). (Lead tape is also available from golf pro shops, and lead is sometimes sold at hobby stores for ballast in radio-controlled model airplanes and cars, but I agree that this is one of the most expensive ways to obtain lead.)
Material v. Density (oz/in3) (approximate)
Pine Wood ~0.3
Craft Plywood (Baltic Birch) 0.38
Water 0.58
Hot Glue ~0.44
Zinc (Cast) 3.8
Tungsten Putty 4.0-4.6
Steel 4.5
Brass 5.0
Cupro-Nickel Alloy (U.S. Nickels) 5.0
Cupro-Nickel Alloy (U.S. Dimes & Quarters) 5.1
Copper 5.2
Lead 6.6
PWDRacing TundraTM Composite 7.1?
Tungsten 11.2
Rukkian wrote:No worries, it was an interesting topic. ... (we serve a fairly low-income area).
Thanks for your understanding. Low-income situations is
exactly why I questioned whether councils should be in the business of regulating ballast materials without adequate justification; a competitive builder usually must spend ~$20+ per car on tungsten or tungsten-based lead substitute.