grinding

[coolman]

I welded a piece of flat 0.25" plate to the side of a 3" x 3" x 0.25" square tube. The plate warped and is no longer parallel to the tube. I need to grind it off without destroying the tube and I am new to grinding. I bought a Milwaukee 4-1/2" 8.5 Amp grinder and got some thin grinding wheels. What is the method to successfully grind this plate off? I plan to weld a new plate where the old one was placed. Any hints or advise so that I can do it right the first time?

Thanks,

[HuFlungDung]

The plate warped? Now, why am I not shocked to hear that?

Grind out the bulk of the filler metal. You'll have to grind in a bit deeper at the joint, depending somewhat on how much penetration the weld puddle made into the joint. Then, clamp the part in a vise and use a big hammer to loosen it up. Once you crack one side loose, just work your way around. (PS: do this in the middle of the day so you don't wake the neighbourhood )

Wear a full size face shield and safety goggles underneath that. Make sure no combustible paper or materials are anywhere in sight, and watch where the sparks are going. Lots of fires start from grinding sparks flying several feet and lodging beneath something.

[scott m]

When you are grinding the plate off, it will start to turn colors when you are close. Also, to keep it from warping next time maybe drill some holes in the plate and tackweld these to the tube when you have it in place. Fill up the holes with weld and buff off level, then make your final weld all round. Also skip welding helps out on the warping problem. Scott.

[Konrad]

You should have no problem grinding the plate off with your thin wheel, just cut into the weld, all the way around, then, bend it back an force with a "large" hammer, that should do it, if not, you have to grind some more.
As for welding your new one, a mild steel plate will have the most distortion after welding, see, if you could get some harder plates, like QT 100, or 4140.
Tack the plate on the ends first, then just do small lengths of beds, on both sides, [not all to one side first]
You could also heat the plate up, after tack welding, nice and hot....just about before it would get red.