Are you having trouble cutting fan holes?
 

What you want is a "Trepanning Cutter" or "Tank Cutter". This is a tool with a pilot drill, which fits in a pillar drill. An arm is connected at a right angle to this drill and a slideable cutter blade is on this arm in parallel with the pilot drill. This cutter will do ANY fan hole size, as it is adjustable and cuts perfect round holes (no jaggies at all). Here is one found in the UK. You should be able to find a supplier fairly easy in the U.S. :D

http://diytools.com/productTypes/9.asp?Guide=9

Whats wrong with just useing a hole saw atachment on a drill?

A tank cutter has a variable radius, so the one tool does any size and its a lot neater (and cheaper), I've used both and I know which I prefer but if you do use one, the panel you are cutting, has to be firmly clamped to the bench.:)

Ive never seen one of these. i would be interested in seing one. the link you posted is broken.

Sorry about the link Superart, I've amended the first posting. Heres a piccy of it.;)

http://diytools.com/productTypes/9.asp?Guide=9

im just seeing a red X, but i think i know what you mean.

Is this what you mean:
http://www.smithfrancistools.co.uk/images/tank.jpg

Yep, that's exactly what I was referring to, thanks.:)

how long does it take to cut a hole with one of those?

Drill the pilot hole first, securely clamp the panel down and drill slowly letting the blade do the work, if you force it too fast it will catch, use plenty of cutting oil. Should take no longer than a couple of minutes. In the UK they are priced about £14, for you in the States should be about $20.

Note: It is very important when using this tool that the electric drill is mounted in a stand (or pillar drill). You need to be drilling at a right angle to the panel surface, so you cut through the panel evenly.

Ho do i keep the part that goes into the pilot hole from slipping?

It wont slip, the centre part of this tool sits in the pilot hole and is the anchor for the cutter blade revolving around it.

OK, i getit, like a compas

Yep, that's right.

my dremel rocks ur lil drill press stuff....thank god for molding =D

I've got a Dremel now but theres no way this can come close to the perfect round hole a tank cutter cuts.:D

thanks for the heads up. I bet next time i buy one of those to cut perfect holes :D