torching through 2 plates simultaneously

[jklingel]

Anyone have any tricks for torching through two plates that are welded together? It seems to help a little bit to (1) go very slowly (2) angle the torch a bit ("bevel") and (3) use plenty of gas. That said, I STILL go along nicely for a few inches, then all of a sudden Mt Vesuvius erupts and molten steel from the top plate blows all over the show. Why the lower plate suddenly cools I don't know. Advice? Thanks. john

 

[D KRAGER]

That's always been a problem for me also.

The problem is that you are not getting heat transfer from the top plate to the bottom. It will be worse when the plates have just a slight gap in them.

Can anyone chime in and say if a plasma cutter would be any better in this situation.???? I've only ran a plasma cutter once in my life.

 

[Bigrhamr]

Usually plasma will not be any better at that. What happens is when one sheet warps or you get any kind of gap between them the arc has to go through the top sheet then hunt and reach for a path to the bottom. It might go straight through but more often it will wander and cut only partway through the bottom or even find a new path off to the side of the top sheet making a big mess. The other big problem with that in machine cutting applications is that the torch height control is usually controlled by measuring the arc length, so if it's stretching out to reach the bottom sheet the height control will drop the torch until it hits the top plate. In certain situations it is possible though. I run CNC plasma every day and have succesfully stack cut 20 gauge that was perfectly flat and stuck together with oil to the point where it had to be pried apart.
Hand cutting small pieces that you can keep tightly clamped together you might do okay at it.

 

[rsanter]

a plasma will be better, but the plasma will need to be oversized for the job.
in other words. if you have 2 plates with a total thickness of 1/4 you will need a plasma with a capacity of 3/16 to 1/2 to blow through them without a similar problem

bob

 

[Hal]

MAPP gas or propane will cut through stacked plates much better than acetylene. You will still get an occasional eruption but it is not as frequent. If you do a lot of cutting on anything besides clean plate, either of these gases are, in my opinion, a better choice.

The flame is not as hot, and the heat is not concentrated at the point of the inner cone, so you can cut without being as careful about the distance you hold the tip from the plate. It is also less likely to weld thin material back together behind the cut. The slag is not stuck as tightly to the edges of the cut off pieces, and is easier to clean up

 

[crewchief888]

Anyone have any tricks for torching through two plates that are welded together? It seems to help a little bit to (1) go very slowly (2) angle the torch a bit ("bevel") and (3) use plenty of gas. That said, I STILL go along nicely for a few inches, then all of a sudden Mt Vesuvius erupts and molten steel from the top plate blows all over the show. Why the lower plate suddenly cools I don't know. Advice? Thanks. john

the trick is to keep the bottom plate as hot as the top plate, slow travel speed, and angling the torch head is keeping the bottom plate hot also.

have you tried preheating the bottom plate along the cut line before starting the cut?

 

[notme_76]

a lil weave always helps...if its a tight joint it will cut not bad, if theres a gap, expect o make a lil mess!

 

[jklingel]

Thanks for the replies. Interesting about the MAPP gas. I thought about pre-heating, but I was nearly out of gas. Dang. I used a whole 200 cf of oxy and an accompanying acet tank to make grapples for my skid steer bucket. I am amazed at how much gas I needed. I guess all the cutting of 1" plate, pre-heating T1 pieces and the bucket, and having to heat and beat two, 1" x 4" plates to bend them (small error on the designer's part....) sucked up a lot of fuel. That damn rose bud is the culprit. No access to a plasma cutter, but I understand that they are super machines if you need one a lot. j

 

[diesel research]

 

[jklingel]

WTF? A gasoline torch? Man, that video was sure interesting. Talk about cutting a few plates stacked up; this requires some research. Thanks for the link. john

 

[brianvantol]

I would probably burn it off leaving 1/4" excess and then trim it back to the line by skimming off the last little bit much like cutting sheet metal.

 

[basthen]

Wow, that's impressive!

 

[v2jafer]

Very nice. Has industry started using any of this yet? Does anyone know?

 

[galooph]

I want one! Very impressive!

Dan

 

[Pukeballs]

Anybody have one of those Petrogen set ups? Too cool.

BTW, whats up with the damn techno music in the video. So annoying. Not everyone's from the Jersey shore.