I'm trying to figure out how to convert a 7spd shimano 600 wheel to fixed gear. Ive heard of something about drilling the axle- but need some more help. Thanks

There's a product by surly called the fixer that will convert freehubs to fixed, but I'm not sure if it works with 7 speed stuff. I assume it would but you'd have to check on their site.

The fixer or I think I have heard of some technique involving the freehub body and well placed JB Weld

You can remove the freehub with a 10-mm hex wrench, then use a torch and brazing wire to braze the internal parts together.

A better option is to buy a formula hub (about $45) and rebuild the wheel. It'll take a few hours if this is your first wheelbuilding experience, but it'll be worth it in the long run.

Edit: before you braze the freehub, be sure to soak it in solvent to remove the grease from inside, otherwise the brazing won't adhere to the metal.

... and then let the solvent evaporate. Because common sense isn't all too common. Also, there are a few articles on fixing a freehub in the how to section of 63xc.com.

-Rob.