Worth it to rent a plasma cutter?

[Lucy's Driver]

I'm in the process of cutting the cast frame end front track bar mount off my TJ. Its a big cast piece factory welded to the frame on two sides: bottom of the frame and the inner framerail. I've gotten through the welds under the frame with an angle grinder. It took many unpleasant hours to do this.
Now I have to get most of the inner section of the ear off. Because I need to have the frame underneath it mostly intact to weld on the mount I'm fabbing up and due to the tight confines the only tool I can get in there is the angle grinder and in such a way that I can't cut the welds: I can only grind the entire section down. This is about 1/2 to 3/4 of cast.
I've never used a plas before but I can get the mig welder in there easy enough, so I figure the head of the plas would fit.
Basically my question is this: would a pretty decent welder whose never used a plas before screw it all up and hack the frame?
Basically I'd need to cut the welds in such a way as to not cut the frame. I have plenty of scrap around the garage to practice on.

Sorry no pics, but if someone has a pic of the stock cast ear on a TJ, especially from the inner framerail view, please post.

[NVCJ]

Plasma is the way to go.Make sure you specify thickness you are cutting when you rent. My little 250 will only cut up to 5/16..Makes for a clean job.

[Scramblah]

Have you thought about using a plain old Acetylene torch to cut the weld? I used my torches to blast off a bunch of my welds on my CJ. Just as long as you keep the heat concetrated on the weld you should be able to do it without messing up the frame.

[302YJ]

I agree, acetylene is probably just as good

[Lucy's Driver]

Originally Posted by ryankopecki

Plasma is overrated. And yes I do have one, for cutting sheets into strips quickly. For most other things I still use a torch. A torch is a very valuable tool if you can use it good, other than cutting, it can also heat things and blow out welds. And then there's the air gouger, it hooks to an arc welder and air compressor and blows out welds faster than you could make them, that would probably be the best tool for the job you're doing. It actually does use plasma and it heats the work piece very little.

A buddy of mine is a breacher on a SWAT team. One of their cool breaching tools looks like an arc welder using very large sitcks. This device is hooked to a compressed gas tank (not sure what gas they use). This is used to burn quickly through metallic doors and also to get into safes. Is this an air gouger?

Second, does anyone know some place that would rent a torch or air gouger (or plas) in the northern NJ or eastern PA area? I've tried some searches and come up empty.

[D60]

What sort of "cast" are we talking about here?

I've tried to hack up a wheel bearing hub flange with my plasma (5/8" cast .... iron? I'm guessing?) and it took forever & made the ugliest cut you've ever seen. But I've cut 1/2" mild steel with it no problem. It's rated to cut 7/8" and sever 1.25"...............but cast is clearly different.

Bottom line, be sure the plasma will do what you want.

[randii]

Originally Posted by Lucy's Driver

A buddy of mine is a breacher on a SWAT team. One of their cool breaching tools looks like an arc welder using very large sitcks. This device is hooked to a compressed gas tank (not sure what gas they use). This is used to burn quickly through metallic doors and also to get into safes. Is this an air gouger?

Nah, that's a Broco burning setup (Google). I got to burn a half-rod of this at a vendor show a while back... I cut up a scrap engine block like butter. Picture an exothermic cutting rod hooked to a pressurized 02 canister. Light it, fire it, and you can cut underwater, underground, you name it. No way they'd let you use it in a junkyard, but man would it make pulling parts a breeze.

Randii

[couchracing]

Plaz is the way to go when gouging welds out. If you can turn the head to the side it's like a little Jedi lightsaber. You can typically rent the Force for about 40 bones a day. Remember, clean dry air, it's your friend.
To all the peeps out there in internet land, electrodes and tips last a long time. Just because it's called a consumable, doesn't mean you change it out every 1' of cut. Good luck with you quest, Grinding sucks. Scott.

[Just-fabricate-it]

I'd opt for the cutting torch myself. Mainly because I think its easier to control . I have cut off mounts with my plasma cutter and it seemed the consumables got eaten up quicker. If you even 'blink or sneeze' while using the plasma cutter it is going to cut whatever gets in its way in half a heartbeat. For me, in these situations, the light plasma torch can get me into trouble. By the time I let go of the little button I have a hole or 1" cut where I didn't need one.

[Foxfab]

I have both and I'm in Central CT if ya wanna drive

[jerseyzuks]

Originally Posted by Just-fabricate-it

I'd opt for the cutting torch myself. Mainly because I think its easier to control

I am totally confused by this comment. I feel I have a lot more control with the plasma cutter than a torch. With an plasma cutter, it's just "point and shoot". With the torch, is it constantly lit, so you have an open flame to worry about while crawling under and around a vehicle. Plus, with a plasma cutter, the heat affected zone is far smaller than a torch.

If you are having trouble with the torch slicing through things too quickly, can't you just turn it down? I thought all of the larger plasma cutters were adjustable.

[Just-fabricate-it]

The reason I like the torch for cutting some things off is that (at least for me) is that once I get the plasma cutter cutting and moving around I tend to forget to let go of the switch some times and it just keeps on its merry way cutting away Yeah, I know, dumb operator. The cutting torch make me think a little more and yes its harder to get into those tight spots.

My experience with the plasma is I have a hard time controlling cutting something big/bulky off of a thinner piece without accidently slicing the thinner piece. With the torch I can sort of watch it happen at a slower pace.

I probably need more experience with the plasma but I have more experience torching things off so thats what I go with in certain cases. I tend to use up the plasma consumables fast when I'm 'butchering' things off.

[whthilux]

there is absolutly no HAZ w/ a torch built in pre,during & post heat.