Welding question

[fireguyfire]

How would you guys go about making a small circular patch to weld up a hole in 18 gauge, say about a 1" hole?

[Chryco Psycho]

Hole saw ?
Or better yet a knock from an electrical box

[7E-Bodies]

My method is to place masking tape over the area to be welded, then trace the exact hole. I then have the exact pattern to cut out. Cut it a hair large so you can gradually shape it to perfection on a bench grinder (using needle nose vise grips and required safety gear). Once I have it perfect, I use the right clamps to hold it perfectly flush. I also use a piece of 1/4" copper plate clamped behind the weld to prevent burn through. The weld won't stick to the copper.

Kevin

[tparker]

I fretted over this for a while, but it isn't that difficult. If you can get pre made circles, that would be great. But I just cut out a circle with tin snips that is close to the size of the hole. It should be close but doesn't have to be perfect. Just make suree there isn't any huge gaps. As mentioned above, a whole saw is perfect assuming you have something for the point to drill through. If not, then you might want to use a die grinder to grind a hole.

[76orangewagon]

Hole saw ?
Or better yet a knock from an electrical box

X2 on the electrical box knock outs

[jamesroney]

Is this a trick question?

The fastest way to weld up a round hole (like for an antenna, or some other drilled hole) is to cut the hole square, and install a square patch.

Round plugs are a pain in the ass.  If you are going to MIG weld it, then the corners won't matter.

A 1 inch round hole has 3.14 inches of weld.
A 1 inch square hole has 4 inches of weld.  That's about 10 seconds of welding.

In the time it takes you to find a round disc from an electrical box that is exactly the right size, grind off the zinc layer, fit it in the hole, and get it tack'ed in place, I can use a 1/16 wheel on my die grinder, square up the hole, shear cut an square patch, tack the corners, and stitch the rest.

Hole saw "holes" make good plugs, but you have to dress up the edges for the inevitable flange from the sawcut.  And you have to weld up the center hole.

My $.02.

[IRON MAN]

Good idea James. I also like to use a magnetic plug weld tool for sheet metal...saves time too.

[750-h2]

Welding any square patch is likely to cause distortion. When making any patch, shaping it with curves will always do a better job than shaping your patch with angles.. 

[jimynick]

Welding any square patch is likely to cause distortion. When making any patch, shaping it with curves will always do a better job than shaping your patch with angles.. 

Yeah, I agree with that. Think about it again- you're pushing heat into a corner, twice. 

[JS29]

Any aggressive welding has potential for distortion, The same is true for grinding.