How to Plug Weld - and Why You'd Want To
A viewer is making some furniture and wants to make some T-joints but has very tight clearances. She doesn't want to have to grind all the welds so the drawer will slide in and out. Is there a way to weld it, make sure it's secure, and not have to do all that grinding?
Yes: plug welding. "It's really easy," says Kevin.
Draw a line on one piece of metal where you want the other piece of metal to sit. Then mark where you want to drill holes. Then put the other piece of metal on the line over the holes and weld right through the holes.
Before he drills the holes - ANY hole, Kevin says - centerpunch where you want the hole. That makes it clear to you where you are going to drill and gives your drill a place to center so it doesn't walk across the metal and end up with a hole off center.
Kevin is using a woodworking centerpunch. He puts the pointy end where he wants the hole, pulls up on the other end and lets go, creating a mark where he wants his hole.
Now he puts on his safety glasses and goes to his drill press. As he drills, he explains how important it is to just use the weight of your hand to cut. Pushing down too hard just damages the drill bit. Drills last a lot longer if you don't push down hard!
With his holes drilled, Kevin steps over to his bench grinder, which he uses to buzz off the back of the metal where he drilled the holes. You can use a handheld angle grinder, too.
Kevin has stuck the bottom plate to the edge of the other plate, which is held on a welding magnet. He looks down through the holes to see the bright shiny metal of the bottom piece.
The magnet is stuck to the bench, the ground is clipped to the bench, and he has his Everlast PowerMTS 251si set on TIG mode at 131 amps.
Now he'll come in with the TIG welder but no filler wire and just tack through the holes - just on / off to spot weld it.
Kevin knows that the two pieces of steel are at right angles because he has the welding magnet sitting flat on his welding table, and the two pieces of metal perpendicular to each other on two sides of the magnet, so he has a nice right angle.
He has the welder set on 2T, not 4T, so he can just zap through the hole and let it go, then works his way along as he welds. Kevin then tacks through the holes.
Next he comes back with filler wire to fill in the divots so he can grind it smooth again.
Now the moment of truth! Kevin removes the pieces of metal from the magnet and shows that he has a nice clean T joint at 90 degrees and no welds to clean up. On the outside, he can use a grinder to grind it smooth. Now you're ready for your finish.
But first, stick around for a moment to see if Kevin can, well, stick something else ....
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