September '18

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60 THE SHOP SEPTEMBER 2018 All that's left to do is grind off what's left of the spot welds. Plasma-gouging this series of five spot welds took about 2 minutes. moving. Or continuously press and release the trigger so that the top-layer metal never gets hot enough to affect the bottom layer. To use this method, set the amps as low as they will go. The Hypertherm Powermax45 XP system I use goes down to 10 amps. If you have a system that allows for air pres- sure adjustment, set the air pressure at the lowest setting. Lay the plasma torch at a flat angle next to the spot weld. Press the trigger and use an up-and-down feathering technique with the torch to gouge away the top layer. It takes a little practice to get the hang of it. Make sure to practice on old parts with spot welds until you feel comfortable with it. It takes me less than 30 seconds to go through a spot weld using this technique. Another place the plasma system comes in handy is in hard-to-reach spots. There are places where it's difficult to fit a drill or grinder. In those circumstances, set the plasma on Cut, place the end of the torch directly over the spot weld and precisely pierce through it. Granted, the hole will pass through both layers, but other methods probably would have the same result, as the difficult access makes it harder to be precise with your tools—if you can even fit them in there. DRILLING SPOT WELDS If none of the above methods appeals to you, drilling is one of the oldest techniques for removing spot welds. You won't need any special tools—just a drill and plenty of good-quality drill bits. This method works, but it takes more time than the other methods and the drill bits tend to wear down quickly. The biggest Here's the end result of plasma-gouging a spot weld. It took less than 30 seconds to gouge around the weld. Look closely and you can clearly see the bottom layer of metal is pretty much unaffected by the process. The dark shadow is the separation between the two layers of metal. In some cases, you can hear the pop of the layers separating as you're gouging. The narrow width and awkward location of the mounting flange of this taillight panel makes it challenging to remove the spot welds. The plasma system quickly pieced them away. No plug weld holes needed to be drilled into the new taillight panel. I simply angled the MIG torch and plug-welded from the opposite side as the holes were in the mounting flange. In hard-to-access areas, it might be easier to pierce the spot welds with a plasma system. The Eastwood Skip-Proof Spot Weld Cutter worked better than any other spot cutter I've used. It has a 3/16-inch pilot drill bit with a 3/8-inch diameter cutter. It costs $38.99 and replacement drill bits and cutters are available. When cutting out spot welds, a center- punch is used to create a divot. The drill is held at an exact 90-degree angle and gentle pressure is applied. The small drill bit in the center of the cutter creates the pilot hole and gives stability to the cutter. The spring-loaded drill bit hits the second layer and slides up. The cutter slices around the weld through the first layer. I'm using a Hypertherm Powermax45 XP set on 10 amps. The torch is outfitted with precision gouging consumables. Place the torch next to the spot weld and gouge a path around one side of the weld, flipping the torch up and down to wash away the melted metal. When you see the metal starting to melt or see the bottom layer, turn the torch upwards—don't allow the arc to dig into the bottom layer.

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