I'm building a set of headers that requires welding some pieces together.
My question is this:
When I butt weld the 18 gauge tubing together, I want to grind the welds flat and smooth for a good appearance.
I can't seem to get the welds ground flat; there's almost always a ridge that appears -- worse in curved sections. If I try to grind out the ridge in a curved section, I sometimes grind a hole in it.
Here's my process: tack weld the tubing together. Weld the tubing up completely with my Miller 210 Mig. (Heat set on tap 2, wire speed 35)
Grind the welds with a 60 grit flap disc. Sand the welds with a 80 grit 2" disc on my die
grinder. Use a 3M 4" stripper disc on my drill to smooth it all out.
What am I doing wrong? If I weld several short pieces together it looks bad with all the seam ridges.
I have never built headers but have lots of experience grinding welds on sheet metal. I would recommend using a weld buster in the die grinder to start with (its a triple thick cut off wheel I can't remember the real name) always working across the weld and stoping about a 1/16th from your base material then I would step up to a 40 grit hard backed flap wheel or roll lock sanding disk in the die grinder ( a angle grinder Is to big and clumsy for something this small) once again work across the weld to where your just starting to grind the metal on either side if the weld but the weld should still be slightly visible then switch to 80 grit on a High speed sander to finish up you would be surprised how fast that a sander will take the weld down. Always grind across the weld and focus on bringing the centre of the weld down and the edges will follow don't try to feather the edges till you have switched to the sander. Hope this helps and you can follow me sometimes I ramble
I have built a lot of headers over the years and in my opinion it will be tough to mig a set of headers together and grind the welds flat and have them hold up. Usually the welds will not be very strong after the grinding and will likely break.
Gary
Didn't have any luck mig welding my headers and grinding them smooth. Got lucky and talked my boss into letting me bring them into work and tig welding them an then they'd grind smooth. Not a welder by profesion so I'm not saying it can't be done.
It sounds like you're just stacking the weld on the surface and not penetrating the tubing. Then you grind the ridge off and there's nothing holding things together.
Tig would be the best apearing (as long as the operator can lay down a good bead) and grinding away all the bead leaves you with no weld. Gas welding is my second prefered method for welding light guage metals.
Rob
Wish I could Tig weld ... I have the welder to do it, just haven't learned how to do it right.
When mig welding, I turn the heat up while stack welding -- so the penetration is there;
I can look into the tubing and see the backside of the weld is almost as tall as the front side.
X2 on tig welding. Mig welding is more for speed. With tig, it's about fusing the two metals together and only using filler to fill the weld pool up.
There are loads of lessons on the net on how to tig weld and once you get the idea it's practice, practice, practice.
Cheers
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