The top of my box sides looks like a piece of swiss cheese. The holes where probably drilled for tool boxes, toppers, etc. I have a Miller 175 wire feed which sould be sufficent. How do you go about welding a hole? Can you just start welding the hole and it will fill in or do you need somthing temporary under the hole for the weld to build up on?

small holes less than 3/8 inch i'll just go in a circular motion to fill them// get a piece of scrapmetal drill a bunch of holes and practice b-4 starting on the bed

A piece of copper clamped flush against the back side works wonders.

The copper works very well you can get it at the hobby store about 1/32" thickness. use anti spatter spray on the copper and by all mean never hold it with you fingers while trying to plug holes... it hurts.. do the technique cdowns describes.

of course what they neglected to tell you with the copper trick is to get it under the bed rails you'll need arms that are at least 6-7feet long:)

the copper does work if the holes are accessable //i'll just use a scrap of copper tubing smash it flat with a hammer around a piece of wooden dowel for a handle

Thanks for the tips. Does the copper get ruined with every hole you patch or doesn't the heat affect it? After you weld over the copper will it just pull off by hand and be able to move onto the next hole?

nothing sticks to the copper it can be reused many times i usually loose them b-4 using them up might want to wire brush them off every once in a while

some times i'll ducttape them in place if i cant hold or clamp them while welding

What I have always used is a thick piece of aluminum stock held under the area to be filled. Just like copper, the steel wire won't melt into it.