THE SHOP

September '18

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58 THE SHOP SEPTEMBER 2018 I t's one of the most dreaded tasks in automotive panel replacement. Very few people enjoy removing spot welds. But it's also one of the most important steps in the process. When you're replacing a panel, you want a good, solid, undamaged surface to mount it on. Eliminating spot welds the wrong way can damage the bottom layer of metal, possibly adding hours of repair to the job. The technique used to remove a spot weld also depends on its location. Restorers need to have several techniques in their wheelhouse and be able to quickly adapt to whatever technique the spot weld situ- ation requires. The ideal result of removing spot welds is to cut through the first layer of metal without damaging the second layer under- neath. Thing is, the spot weld is a little harder than the metal surrounding it. Anyone who has ever drilled or tried to center-punch a spot weld will know this firsthand. That's why the cutter or drill usually used in these instances wants to slip off the spot weld and dig into the softer surrounding metal. And it's why some technicians prefer to use a grinder, cut-off wheel or plasma system to remove the spot weld. Let's look at the most popular ways to remove spot welds and then examine a newer process. We tested and timed three of these methods to get a handle on what works best in a variety of spot weld removal circumstances. SPOT WELD CUTTERS Using a spot weld cutter was the third- fastest method we tested. There are several styles of spot weld cutters for customizers to consider. The first uses a small centering pin or drill that contacts the surface to stop the cutter from wandering. The pin is on a spring so that once pressure is applied it depresses and the circular cutter begins to cut through the first layer of metal. The cutter is much like a hole saw and is slightly bigger than the spot weld. Cutters can be replaced when worn or swapped-out for different sizes. Spot weld cutters like this range from $25-$75. The second spot weld cutter style is sim- ilar, only it has a centering drill instead of a pin. The drill bites into the surface and gives the tool stability so that the cutter is stable as it slices around the spot weld. The hole-shaped cutters can also be replaced when they wear out. The lon- gevity of these first two styles of cutters varies greatly depending on the quality of the cutter and what you're cutting into. The third style of spot weld cutter is the most basic. These are simply a very-wide- but-flat drill bit with a self-centering tip to help keep the tool from wandering. But, since they are made from one piece of metal, once they get dull they need to be sharpened or replaced. These cutters come in various sizes—1/4-, 5/16-, 3/8- and 1/2-inch. Prices can range from $30 to more than $100 for a kit, depending on the quality. To use any type of spot weld cutter, it's best to start by creating a divot in the middle of the spot weld. Use a metal punch and hammer to form the divot. Then line up the cutter and try to cut only through the top layer. As I noted, this was the slowest of the three methods we tried, averaging 3-1/2 minutes per weld. GRINDING OFF SPOT WELDS Grinding was the second-fastest method we tested. Some folks use a cut-off wheel for the entire procedure. Others do the bulk Fast & Easy Is there really such a thing? By JoAnn Bortles To grind off a spot weld, first grind off most of the top layer of metal without getting too far into the spot weld. Then switch to a cut-off wheel to precisely remove what's left of the top layer. When grinding off spot welds, this is what you're looking for as you're grinding. See that little circular line? That's the spot weld! The grinder and cut-off wheel have worked through the top layer of metal. That line is the bottom edge of the top layer. Now use a chisel or Seam Buster to separate the layers. There are several methods for removing spot welds when replacing automotive panels. We tested and timed three alter- natives to simply drilling through them. 58 THE SHOP SEPTEMBER 2018

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