Cutting large holes in the stainless firewall

Blake.Harral · #1 12-30-2007, 10:22 PM

When I built my RV-4, I cut one large hole in the firewall for cabin heat. Used a hole saw turning slowly, and a lot of patience. I eventually got the job done and it turned out OK

I am now retrofitting Cabin Heat to an already built RV-6, and the location for the 2" hole is not very accessible. I have purchased a Greenlee punch for this job, but my limited experience in 'shearing' stainless makes me wonder if the punch is a good idea.

Does anyone have any experiences to report with regard to using Greenlee punches to make openings in the stainless firewall?

Captain_John · #2 12-31-2007, 06:29 AM

Nuttin' to it but ta do it!

I have used Greenlee punches on more materials than you can shake a stick at. They have never failed me. It will work fine.

The stainless is ideal. I am sure it will slice the firewall as good or better than you expect.

Do it up!!

CJ

Randy Hooper · #3 12-31-2007, 07:02 AM

The Greenlee punch will go through the firewall like butter. I used a step drill to make the punch bolt hole. It will cut that size better than a regular drill bit.

Caution! I found that my punch was sized for conduit, so the 2 inch side was to large. Fortunatly the other side of the punch was 1 1/2 and actully cut the 2 inch hole I needed. To be safe measure the punch before you start.

Randy Hooper
RV-8

videobobk · #4 12-31-2007, 07:10 AM

I used a Greenlee with no problem EXCEPT it was a bit small. Something like 1/8", IIRC. Used a 1 1/2" drum sander to bring it up to size. This was done after the engine had been hung, something I don't recommend, but it worked out fine.

Bob Kelly

McFly · #5 12-31-2007, 08:55 AM

For the big holes like the heater, I used the sanding drum attachment on my Dremel. It actually enlarged the hole in fairley short order. Keep a wet towel handy to keep the temp down.

I'd rather use a Greenlee but if you are on a budget or just don't want to wait, it might be the way to go. Good luck.