I am going to install a power antenna in my 69 Camaro and the instructions says to drill a 22MM hole in the fender.What size drill bit does this match?

22mm= 22x.03937=.866 so you can use a 7/8 (.875) drill.

Or, use a 55/64 and file away the extra 7 thousanths, while a 7/8 will get you 9 thousanths over. If I were doing this, I would go 55/64 because you're going to want to file the hole a bit to take off some sharp edges and such. You may find it safer to make the hole undersize the first time...

Why not use a 22mm metal cutting hole saw?

Better yet: use an electrician's hole punch, like a Greenlee 724BX. Fast and clean: you won't even have to file/deburr.

I agree with z28andrs, Greenlee punch makes a cleaner hole and doesn't dimple the surrounding metal, as in a hole saw.

Besides, when was the last time you seen a hole saw make an exact hole relating to its size?

Millimeters to inches: http://www.aboveboardelectronics.com/raf/reference.htm

Fractional equivelants: http://www.aboveboardelectronics.com/raf/decimal.htm

Originally posted by Everett#2390:


Besides, when was the last time you seen a hole saw make an exact hole relating to its size? Well I certainly wouldn't use a hole saw if I was measuring the hole to the nearest ten thousandth, but it should do just fine for an antenna hole.

The greenlee punch sounds like a great idea, but I would definitely do a test hole on a piece of metal that isn't perfecly flat, because the top of your fender isn't. If it can make a clean hole without buckiling or puckering the surrounding metal, then it would be the tool of choice. My guess is, (and I've never actually used one, so it is purely a guess) that the tool would first flatten the metal, and then punch through it.

http://www.camaros.net/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=3;t=004665

I still haven't pulled the trigger on mine yet...so I'm listening!