Poor Man's Gram Scale

[NamG]

I saw this in a video presentation for the IIT International Bridge Building Contest and thought it was interesting.

Take a meter stick and balance it on a pencil. Put your bridge on one end. Use nickels on the other end, each nickel has a mass of 5g. This gives you precision to every 5 grams. To get within 1 gram, take another nickel and place it at every 10cm until it balances out. This is as far as the video went, but I imagine you could get even more precise if you wanted to. The principle is very similar as a triple beam balance.

I don't have my bridge building stuff, i.e. my gram scale, with me (away at college), but could someone verify that this works? Is it an accurate method for weighing bridges? Obviously it isn't the most precise, but for someone who doesn't have their own gram scale it could be helpful to give you a general idea of the weight of your bridge. Maybe with practice one could actually get very close.

If anyone is interested, here is the video:
http://video.google.com/videoplay?docid ... 1445&hl=en

[jazzy009]

How much does your bridge approximately weigh? if you wanted to be creative you could get whichever teammates are building your JYC scale and see if they can weigh it. That'd be cool, an event serving a purpose in real life!

[rman]

http://cgi.ebay.com/100-x-0-01-Gram-Dig ... 7C294%3A50

This is a 100 gram scale that can measure to 0.01 gram. Total cost with shipping is $15.99. I hope every SO team can afford that kind of expense. I would expect that most teams spend more then that on the glue they use on their bridges. Between the Sigment, cyanoacrilate (super glue) polyurethane (Gorrilla glue) and some wood glue I used, I am sure I spent way more than $16 on just my glues. Actually the balsa probably cost less then the glue. Anyway, get a good scale that can read to at least 0.01 gram, you will need it for measuring pieces of the bridge as well as the completed bridge. It is so so hard to build a good bridge when you have no accurate way of measuring the weight of the pieces and glue going into it.

[NamG]

I agree with you, rman. A good, precise, digital gram scale is a must for any serious builder. I was more interested in the novelty of this method. I can't test it out myself right now, and was hoping someone from the forum could mess around with it and post results.