Automotive Welding

Any precautions I need to take before doing a repair in the bed of a 2007 pickup truck? Is it necessary to disconnect the batteries first?

Reply to
Bob La Londe
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I have never disconnected the battery on any vehicle I have welded on. Just make sure you have a good ground connection directly to the part you are welding on. Your results may vary. Steve

Reply to
Up North

I was thinking I would use a magnetic connection terminal right next the piece I am welding in after grinding the paint off so it would make a great connection.

Reply to
Bob La Londe

I would not grind paint off. But be sure that whatever you ground to isn't isolated by rubber. Maybe just a little brushing to remove road crum would be as good as grinding.

Steve

Reply to
SteveB

I've never had any issues either... but also suggest a good ground.

I've heard that leaving the ignition switch in the off position is good protection for the emission control computer... as in living without the stereo during weld operations.

Also, take a good look at the 'other side' of the repair area, you don't want any surprises.

Erik

Reply to
Erik

Too late. Paint is gone. Didn't see any major issue since I have to clean, prime, and paint the welded area anyway.

Welding that thin stuff is sure a pain. Had to do micro welds and let it cool for a second between each pull. Still looked like crud, but I planned to grind it smooth anyway.

Reply to
Bob La Londe

Yeppers. Its right over the pumpkin. I threw a couple welding blankets in there for good measure anyway.

Reply to
Bob La Londe

"Crud" usually comes from paint, oil, dirt, or shielding gas that is being blown away by the wind. And it don't take hardly any wind. Sometimes, too, it comes from a weld not being backed up, and infiltrating air coming in from the back. In that case, copper backup strips are good because they block off the air coming in, act as a heat sink, and don't melt and stick to the weldment.

I define "crud" as spongy looking welds. If it has holes like a sponge, you got paint, oil, dirt, air, air infiltration, or shielding gas not being on, not being on strong enough, or being blown away. If it doesn't look spongy, but just cruddy, you just need some lessons.

Yah done good by doing a series of tacks. Next time, just wait until the red goes to black when viewing through your shield, and stack those little tack welds like dimes. But you have to wait for the previous one to cool. Hint: there's still enough light while one cools to have that wire in exactly the right place for the next. Take some scrap and practice. I guarantee, you'll be remarkably better in fifteen minutes. Tack every two inches or so first, then fill in between tacks, or the joint will spread out, and it's a whole nother discussion.

Steve

Reply to
SteveB

On Sat, 29 Nov 2008 14:40:18 -0700, Bob La Londe penned the following well considered thoughts to the readers of rec.crafts.metalworking:

Best practice is to disconnect the battery, computer, and the alternator.

I've welded on vehicles without doing this with no damage, but with the advancing complexity of computerized everything on a vehicle, I don't think I would do it again.....

YMMV....

Reply to
Gene Kearns

"Gene Kearns" wrote: I've welded on vehicles without doing this with no damage, but with

^^^^^^^^^^^^^^^^^^^^^^ I've welded on vehicles without wearing suspenders. My belt held up my pants quite well, and no damage to the vehicles occurred, but with the advancing comlexity.... :-)

Reply to
Leo Lichtman

Make sure you don't get near any of the combustable fluid lines or the gas tank. Like everyone said, attach the ground wire clamp onto the piece of metal you are welding to. Never let the current run through a bearing race or through the whole truck frame. If the engine to chassis bonding is defective the voltage drop will wipe out electrical components.

John

Reply to
john

I'd leave the battery connected as a buffer or filter condesnser to absorb any transents which should be none.

John

Reply to
john

I had one fellow tell me to ALWAYS disconnect the battery before doing ANY welding on a vehicle. It's a simple precaution and doesn't take all that much time.

Reply to
Al Patrick

Basic electrical fact that by leaving the battery connected you essentialy have a low impedance circuit which is less likely to pick up induced stray currents. The whole key is where the ground connection is connected and if the welder has a floating ground, it should but if it is internally shorted, all bets are off. The ground return is now connected to the earth ground and the incoming electrical ground. Weld on another piece of equipment that is partially grounded to the electricl building ground and anything can happen.

John

Reply to
john

Disconnect the battery and short pos to neg. Makes "resl low impedence" circuit to clamp any strainduced voltages.

Reply to
clare

wrote: Disconnect the battery and short pos to neg. Makes "resl low

^^^^^^^^^^^^^^^^^^ I tried that and the cable turned red hot before I could get it unhooked. I'll bet you meant short the car side, not the battery. ;-)

Reply to
Leo Lichtman

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