butt head, butt weld.., I need some help |
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butt head, butt weld.., I need some help |
TravisNeff |
Feb 14 2005, 02:09 PM
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#1
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914 Guru Group: Members Posts: 5,082 Joined: 20-March 03 From: Mesa, AZ Member No.: 447 Region Association: Southwest Region |
Hey all,
I have been trying to patch up A/C holes in my tub and having a helluva time blowing holes in the metal and voids around the weld area. I start with tacks in the corners and start tacking around the world in an offset pattern, when I have about 12 tacks in a circle I try to join the tacs. However when I tac, I most always blow a hole in the new sheet metal, or in the old panel. I have the worst time in the vertical position. I have ground down both sides of the panel (and patch) to clean metal. If I am not blowing a hole, only about 50% of the weld gets good penetration, when I hit it a little longer I blow a hole. I have even used a sorta chill bar to back the joint (1" copper pipe squished flat with a bend, suggested by another lister). Also, I am making most of my holes just buzzing a tack, not so much once I have an arc established. I have a Millermatic 175, using .023 wire and Argon/CO2 (about 24lbs pressure when I hit the switch), Guide states I should use #2 on voltage and 50 on the wire feed speed. I have no problems welding lap joints at these settings and it sounds like bacon frying when it does it, so I know I am close. I have gone down to 1.5 on voltage and reduced the wire feed to 40, still no luck. I have expanded my stickout (experimenting with 1" plus down to the 3/8's I normally do). The welds suck. Once I get done and grind the welds down smooth I almost always find a crack/void where the metal joins the weld. Weld, grind, weld grind. I can eventually get it right, fixing each one of the patches once I grind it down. I have tried the butt weld clamps, but the gap is huge, I can get the metal to almost (or actually touch) and hold it in with a magnet. What am I missing? Should I be using metal ready to clean the metal even further, try another technique? I am holding the gun at an upward angle and a touch over to the side (hell I have tried just about everything). |
John Kelly |
Feb 17 2005, 02:42 PM
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#2
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Senior Member Group: Members Posts: 692 Joined: 1-May 03 From: Moclips WA. Member No.: 640 |
KT,
Thanks for the kudos, but I'm no master...I overlap lots of places, and I don't care what a panel looks like on the inside...I just like to save my best work for the body skin...butt welds are not that much more work and provide a nice smooth surface for filler if you are not going to metal-finish your welds. Lap joints leave an edge into which filler can shrink over time showing the seam. Or, if you flange the lap joint, you run the risk of distorting the panel that is flanged where the seam curves....and use more filler. Just a question of making an informed choice....we all make our own rules in the end. Some of what I do would horrify a concourse judge...do I care? No. John www.ghiaspecialties.com |
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