In a past thread I brought up the subject of replacing parts of the floor in my 67. I bought a pneumatic cut off tool with 3" wheel. This thing sucks at cutting. I just marked out my new pan where I wanted it cut, and this thing barely puts a dent in the pan. It would take me at least a few hours to cut this one section of pan (removing a couple inches from the edge of the entire pan)

I was wondering if a plasma cutter is ok for something like this? I could probably rent one for the day and do the entire floor. I've never used one, so I don't even know if this is the way to go, but I know that cut off wheel sure isn't

I use a cut-off tool quite a bit. (1/4's, Drop offs, outer wheel houses, floors, Ect.) - Buy the best wheels you can & I reccommend using 1/16" as they don't need to remove as much material.
The plasma would work but you want to keep clear of the floor braces. I like the cut off tool because it leaves a nice edge of you are using that edge to weld to. They are very noisy & dirty though.

LK

As you found out a cut off wheel sucks at cutting metal. My cut offs are pretty much grinding tools not cutting tools.
Depending on what am doing Ill use an air hammer with a sheetmetal ripper bit. It will eat that metal up.

I have a Miller 375 xtreme that I love. With practice you can remove spot welds with a plasma cutter and not harm the underlaying panel.

You can get a good hard fast hitting Ingersoll rand air hammer for about 45 bucks. You can go to sears and get a 4 piece bit kit for about 20 bucks.
Its a great tool to have, I rough out ALL my panels with the air hammer or plasma.

Air hammer makes no spraks no mess and not that much louder then a cut off, cheaper too...Eric

I've used 3" cutoff wheels on every piece of sheetmetal I've replaced (floors frt to rear,1/4's,rockers,etc) with little problem,but you have to have a compressor that will keep up. 1 thing I found is to use the 1/32 thick for cutting and 1/16 an up for grinding. The biggest drawback I have is noise,mess,and expense (3m brand are good but expensive)

The problem might be due in part to my compressor, that and I think my new floor pans are made of titanium! :) I have an older Craftsman 20gal 5 hp compressor,and it doesn't seem to be keeping up

Die grinders use more CFM's than any other tool. Only a commercial air supply can keep up with one for constant cutting.

Plasmas are great, but you want to keep your floor braces in as good as condition as possible. Do a search for floorboard replacement and you'll get a TON of ideas, methods and advice with lots of good pictures.

I just checked my compressor, and it says it can deliver 7.1 SCFM @ 90 PSI. The cut-off tool I have says it needs 4 CFM @ 90 PSI. But I just read up a little on compressors, and it seems these 'hobby' compressors are pretty much only good for filling tires.

Maybe an electric cut off tool?

A plasma cutter will do the job … if you have one, great. I wouldn’t invest in one though.

Basically, as they’ve said … you’ll have to be very careful and avoid all the crossmembers. The guy that cut my floor with a plasma cutter didn’t pay much attention! But that brings me to my point. Since you still have to remove all the spot welds on the crossmember, the plasma cutter doesn’t buy you much anyhow.

Now, for a secret on shop tools … USE electric!! A lot of air tools are not for home use. The primary reason for using air tools in plants/factories … is we’re not allowed electric extension cords. Air hoses are an easy replacement. Your cutoff wheel is the same as what I bought (and many others), completely gutless. Mind you, there are very good air cutoff’s out there (I have them at work) … but they start at over $300, and consume 20+cfm!!

Here’s what I use … and it is totally ir-replaceable! I have a 7.0A (can always go more amps), 4.5” angle grinder … and purchase .040” Dewalt cut off blades. I use that thing absolutely everywhere. It slices metal so fast, you have to cautious of what’s in it’s path. Now if you want to spend a few extra $$ … what I have at work puts it to shame, that’s a Metabo Slicer. Now that thing has balls. Don’t go any larger though, as this size fits in many places.

Definitely get the angle grinder and cut off wheel, that will eliminate that frustration.

After that, you’ll want to remove the spot welds. I tried the spot weld cutters that look like a mini-hole saw … hated them, burnt up in just a couple spots! I purchased the actual bit that goes into the pneumatic spot weld cutters, and just use it in my drill. The bit will cost you about $20, but it’s sharpen-able … and I still haven’t even sharpened it once. The whole pneumatic tool looks great, but I think they’re like $400, and you’ll have to a lot of spots to recoup that.

Past that, you’ll have to learn some of your own tricks as you go. Cut the floor out in smaller pieces I found easier to handle. I chose to install my floor pan underneath the rocker panel (most people don’t). This was kind of a pain … I cut the spot weld through the top 2 panels (they’re 4 thick in places), then would take a 7-in-1 putty knife and smack it hard with a hammer in between panels to pop out the rest of the spot.

Anyhow, take care. Lots of rambling here. Lose the air cutoff, and get an electric.
Neal

+1 ^

I use an angle grinder with a cut-off wheel. So much better than air die grinder.

I just tried my angle grinder. Works MUCH better than that air grinder. I bought the air grinder thinking they would work better.

It cut through the new pan nice. Now to see how is does on the originals in the car. Any tips or tricks for cutting across the braces?

Get the November 07 issue of Chevey High Performance, great artical on floor replacement and the tools they used. Hope this answers some of your questions. Good luck.
Tom

Actually, the pneumatic hammer with a slitter tool gives about as clean a cut and remaining edges as anything else - and it is cheap and easy to use. Drill a start hole about 5/16" and point and shoot. Ear protection is always needed with any air hammer use. The hard to get to corners can be cut out with a metal blade in a reciprocating sa, if needed. The slitter is safer to use around the crossmembers too.

A single clean cut is best to provide a good pattern for the replacement metal. i usually weld the replacement metal in with about a 1/4" to 1/2" overlap and seal the bottom with seam sealer after the welding is done. then POR or undercoating to finish. OLDED