[mkling]

I had a lot of trouble with this when I started welding. Tried the penny thing and all sorts of stuff. It justs takes practice. I can now weld in holes very easy with nothing behind them. Play with your wleder settings. Start on an edge, and pull it across the hole. Or larger holes, go around in a circle building the edge and then you have it filled.

If you are getting them filled but have pin holes, I'm guessing you need to turn up the power on the welder a little and play with your feed rate. Use thin wire. Or you need to clean things up with a wire wheel. I'm assuming your using a MIG.

[Mr Twister]

Yes, C25 gas, .024 wire. Heat on low setting. Thanks everyone so far.

[First Bird]

A trick I use MIGing holes: I grab a scrap of sheetmetal, a cut-off a few inches long. Then with aviation snips i cut a piece to fit the hole. Don't cut it all the way off, cut it ALMOST off. (sometimes I use wire cutters to do the last cut on 18ga - seems aviation snips like to cut the piece all the way off no matter how careful I am). I leave it hanging off the scrap handle. Then I bend the hanging piece so its easy to hold in the hole. Zap it a couple times. Then wiggle the scrap back and forth to break the handle off. This leaves the little piece tacked in the hole. Easy to finish weld from there.

[Greg Reid]

Originally Posted by First Bird

A trick I use MIGing holes: I grab a scrap of sheetmetal, a cut-off a few inches long. Then with aviation snips i cut a piece to fit the hole. Don't cut it all the way off, cut it ALMOST off. (sometimes I use wire cutters to do the last cut on 18ga - seems aviation snips like to cut the piece all the way off no matter how careful I am). I leave it hanging off the scrap handle. Then I bend the hanging piece so its easy to hold in the hole. Zap it a couple times. Then wiggle the scrap back and forth to break the handle off. This leaves the little piece tacked in the hole. Easy to finish weld from there.

I do this too...also, I will use scrap welding wire for the same purpose. Sometimes I twist it up to get it thicker.
I definitely am not great at filling holes though. In fact, I kinda suck at it.

[63Banshee]

Originally Posted by First Bird

A trick I use MIGing holes: I grab a scrap of sheetmetal, a cut-off a few inches long. Then with aviation snips i cut a piece to fit the hole. Don't cut it all the way off, cut it ALMOST off. (sometimes I use wire cutters to do the last cut on 18ga - seems aviation snips like to cut the piece all the way off no matter how careful I am). I leave it hanging off the scrap handle. Then I bend the hanging piece so its easy to hold in the hole. Zap it a couple times. Then wiggle the scrap back and forth to break the handle off. This leaves the little piece tacked in the hole. Easy to finish weld from there.

This is how you do it. General rule of welding is to not use weld to fill holes.

[Shiny]

I have to fill a hole that's about 3/8" dia. Good info in this old thread!