Firewall Heater Hole

Steve · #1 10-11-2005, 06:31 AM

What's everyone using to cut the 2" hole in the firewall for the heater valve?

Thanks all,
Steve

Kahuna · #2 10-11-2005, 06:44 AM

Beg borrow or steal a 2 1/8" panel hole cutter. Couple of dies that squeeze together to punch out a hole. I borrowed mine from our EAA chapter.
BEst,
Kahuna

McFly · #3 10-11-2005, 08:49 AM

I used a step bit to start the hole. I then used the coarse grit sanding drum on my Dremmel, which work amazingly fast, for final size. Do your final smoothing with a die grinder mounted Scotchbright wheel. Keep a wet towel handy to keep the temp down. Good luck.

kevinh · #4 10-11-2005, 09:43 AM

I used one of those rotary fly cutters, held in my handdrill. It was a pain because access was limited. Worked great - completely safe!

just kidding

A rotary fly cutter would have been a disaster.

I used a regular hole saw bit from home depot. Worked great - the scotchbright wheel cleaned things up nicely.

robertahegy · #5 10-11-2005, 10:58 AM

Hole saw. Cheap and safe if the punch isn't available.

Roberta

Radomir · #6 10-11-2005, 11:28 AM

walmart had a hole saw set for about 10 bucks total.. it was called something like door set.. included two hole saws 1" and 2 1/8"... you'll need 1" for side skins...

johnp · #7 10-11-2005, 01:52 PM

Quote:

Beg borrow or steal a 2 1/8" panel hole cutter. Couple of dies that squeeze together to punch out a hole. I borrowed mine from our EAA chapter.
BEst,
Kahuna

dang, is this timely. i haven't yet cut that hole (my buddy who is building dulled several hole saws on it and wound up taking it to work -- he works for a steel company).

and my instrument punch and die arrived last week. i hadn't thought about using them for that.

thanks, kahuna

john

f1rocket · #8 10-11-2005, 02:20 PM

I actually used the fly cutter in a variable speed drill and it worked fine. If you go slow, you can get it to work. I tried grinding that sucker with my Dremel tools and the stainless ate them up. Of course, you have to have your mount off to get to it with the flycutter.

BTW, you should mount the box as high on the firewall as you can. If you have a fire in your engine compartment, there's less chance of your box melting (if it's aluminum which it shouldn't be) or less chance of it sucking in smoke if the exiting airflow doesn't flow past the heater box.