butt welding 1" plate

bdog · Feb 24, 2014

I say plate but it is actually two pieces of angle iron 6" long butted together to make a U shape. The two bolts go through the two sides and the block and the end that is welded together holds the pin in. I was just trying to make the question as simple as possible regarding the weld in question.

The current one is made out of 6" x 1/2" plate and has two welds one on each corner. I was thinking with the angle there would only need to be one weld.

SquirmyPug · Feb 24, 2014

bdog said:
I say plate but it is actually two pieces of angle iron 6" long butted together to make a U shape. The two bolts go through the two sides and the block and the end that is welded together holds the pin in. I was just trying to make the question as simple as possible regarding the weld in question.

The current one is made out of 6" x 1/2" plate and has two welds one on each corner. I was thinking with the angle there would only need to be one weld.

This is why we need pictures

The more info you give use the better we can help. If the last time it was "fixed" was by an exhaust shop you might be able to just clean it all up and weld it correctly to fix it. If its been repaired several times its probably easier to make a new one though.

bdog · Feb 24, 2014

Yes I know pictures help a ton but I don't have any and was hoping to work on it in the morning. I have the rest of the project figured out I just needed advice on the butt weld of the thick material. I can get some pics tomorrow of how it turns out though.

Gary Fowler · Feb 24, 2014

Double bevel it using 37+- degree bevels. A double 37 degree bevel is less welding than a single 37 degree bevel and doesn't warp as much. Weld a pass on each side as you fill up the bevels so it equalizes the heat input and thus limits the warping. You don't need big rods, smaller the electrode, the less heat input and the less warping you will get. I would use at max 1/8 E 7018 rods. Alternate welding from each end of the joint. Final passes, Weld from the ends toward the middle and stop so the ends of the angle get filled and don't leave the puddle hole low spot.

Contrary to what some have posted about welder amperage, you only need enough amps to effectively melt the size rod being used regardless of how thick the parent metal is. Preheating to 150F is as much preheat as you need even on thicker material and this has nothing to do with effectively burning in the electrode, it is more to prevent stressing the metal when the hot weld metal is applied. SMAW and FCAW/MIG (excepting aluminum) welding is not like acetylene welding or brazing where thicker metal sucks the heat away, these processes apply concentrated heat to a small area so welding a 1/8" plate is not much different from welding an 8" thick plate except perhaps the joint prep.

Brad_Blazer · Feb 24, 2014

The weld volume increases with the square of the base dimension. As a result, a single bevel will require twice as much fill as a double bevel.

ray66v · Feb 24, 2014

Ditto on the preheat.

Set it up right, and you could weld it with anything.

I could weld that with a my SP175 mig. Working with, and around the duty cycle's cut thermal out would be the only issue.

ericher69 · Feb 24, 2014

ray66v said:
Ditto on the preheat. Set it up right, and you could weld it with anything. I could weld that with a my SP175 mig. Working with, and around the duty cycle's cut thermal out would be the only issue.

Just because you could (doubtful) doesn't mean you should.

My previous mig was an sp170-t and there is no way I would even attempt 1/2" with that welder.

Just saying

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Gary Fowler · Feb 24, 2014

ericher69 said:
Just because you could (doubtful) doesn't mean you should.

My previous mig was an sp170-t and there is no way I would even attempt 1/2" with that welder.

Just saying

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I don't think anyone is saying make one pass with your machine and weld 1" thick material. Thickness of metal has nothing to do with size of machine used to weld it with as long as you make multiple passes. I have no idea why manufacturers would rate a machine as welding xx thickness. If it will weld 1/4" thick metal in one pass, it will weld 4" thick metal also, you just have to make a pass, clean it, weld another pass etc till it is filled up. Ability to produce enough amps to melt a .035 wire properly and run at least a 50% Duty cycle is what I would be looking at in a wire feed welder. A MIG welder with less than 60% is pretty useless for heavy and large weldments as you would spend too much time in the cool down cycle on the machine to get very much welding done.

Mark @ Everlast · Feb 24, 2014

That would count out most Millers if you are referring to maximum amps output. Duty cycle is a ratings game with MIG welders. All MIG welders (except the cheapest of the cheap) at some point produce 60% duty cycle. However, if you look at the maximum output, especially of transformers the duty cycle point is usually set well below maximum output. With that said...look for a MIG welder with the 60% duty cycle rating at least in the area of your "usual" maximum amp requirement. If you were going to regularly weld say, 1/4" single pass welds, you're going to need about 180 amps or so with .035. That's a lot, and very few "common" MIGs put that much out. You'd need a 250 amp mig in most cases to accomplish this.

As far as the joint prep. You can get away with 30 degrees on each bevel, for a total of 60 degrees. No need to try to kill yourself with a precise 37 degree. Just make a slight gap at the bottom about 1/16-3/32 for the first pass to get in the root really good. You'll likely want to run a little bit cold and lay down just a minimum thickness in the first pass.