as is mentioned above, you do not need to use a hole saw. In fact, I'd advise against it unless you can't find the round knock-out punches. The hole saws are really messy and have a tendency to wander as you drill.
Go to your local airport and find an aircraft mechanic that will give you a hand. Here's a link to Aircraft Spruce. Scroll down a little and you'll find them.

http://www.aircraftspruce.com/catalo.../knockout2.php

Oh yeah... those work great on electrical boxes for conduit to pass through... but if you try to use them on anything thicker than about 18 gauge sheet metal... you won't be able to get it to cut. Good luck.

Reed, I don't profess to know everything like you, but having used these knock-out punches in the course of one of my hobbies, which happens to be flying and maintaining aircraft, I HAVE gotten quite familiar with these. They work.

I built my own dash and when I did I used a 2 1/8 holesaw. The hole is slightly oversized for the gauge and I made up the diference with rubber electrical tape. This allows you to keep the gauge body from touching the panel and you can get a nice snug fit.

Will they work on 1/8" aluminum 6061? I have a set of greenfields but I never figured they would go through anything that thick.

I can make you a panel if you end up scrapping yours. Is this for your Formula? I have templates for just about every Formula panel along with all the other usual suspects, ei. Fountain, Cigar. Hustler, etc etc. Let me know, I can do Formula side panels for less than you'll pay for a panel punch, ALLOT less! Drilling seldom does a clean job on this type of panel, it leaves a raggedy edge.

Side panels run $100, punched, powder coated and laser etched. How many holes do you want?

Finn
510.541.8124

F31, yes, they will. I prefer to use the hydraulic setup but the Greenfields will work. We use them occasionally to build instrument panels for the Van's RV-series aircraft.
How you been? Long time no see in the chatroom.

I've used them before... Like I said... they work great on sheet metal. I didn't think about them because the last dash panel I made was 1/4" thick aluminum... I KNOW they won't work on that. But if the side panel is thinner.. It may work. Most of the aircraft holes I've seen also have a "flange" pressed into them for stiffness.

I think they will, i have a friend that has a sweet set from snap-on, he used them on car firewalls, sometimes double thick. It may take a little more butt to twist it, but should work. Heck, I'd get the measurement and send to Lofty for a 100 bucks.

Back to the holesaws:
Why would you guys want to use a 2" or a 2-1/8" holesaw to cut a hole for a 2-1/16 gage?
A good 2 inch holesaw cuts a 2 inch hole! Then you'll have to hog it. A 2-1/8" will cut too big of a hole.
Buy the 2-1/16 holesaw to cut the 2-1/16 hole.
You won't find it at Sears, but 2-1/16 holesaws are made by several companies.
Same story for a 2-5/8 inch.
DS