Anyone who has created an aluminum wire bird's nest in a wire welder's gun knows what a headache it can be. It is easier to unroll tangled barbed wire.
Once rare on the farm, aluminum welding is more common with increasing numbers of aluminum grain boxes and livestock trailers needing repair. Farmers have taken to buying spools of aluminum electrode. But feeding aluminum wire down a welding gun's cable is like pushing a wet noodle, says Jon Ertmer of Miller Electric.
"Think of steel electrode as a hard noodle," Ertmer explains. "It has more column strength, allowing it to be more easily pushed down a cable without the wire folding over on itself when it meets resistance (like bends in the cable)."
Aluminum, being a softer metal, is like a wet noodle. Push it down a cable that has lots of bends and, well, you can get a bird's nest. The wire folds over on itself forming a clump.
Now you can get by welding with aluminum by keeping the gun's cable as straight as possible. "I've even seen fabricators tape broomsticks to the gun and cable to keep them straight as possible," Ertmer says.
Or you could invest in a spool gun. As the tool's name implies, spool guns carry a supply of welding wire in small, 4-inch-diameter (or smaller) spools. That wire travels less than 12 inches (depending on model and make) from the spool to the tip of the gun, says Frank Armao of Lincoln Electric. Electricity and shielding gas (flux-core aluminum wire is a rarity) is piped down the gun's cable from an existing welder.
The beauty of spool guns is that they come with cables stretching from 12 to 50 feet and longer. That makes them ideal for repair work inside the hopper bottom of a semitrailer truck's grain trailer. And since most spool guns work with either aluminum or steel wire, the tool comes in equally handy for repairing grain legs, grain tanks on combines, any work that's a long way from your welder.
What makes a spool gun an almost essential tool in any welder's arsenal is that they are "fairly simple to use and provide the benefit of being relatively inexpensive," Armao says.
For this article, entry-level spool guns are featured. But the market has an array of advanced, feature-rich models. A good example is Lincoln's line. The Magnum 100SG is an aluminum-only gun with few features. But for $684, you can buy the Magnum SG, which provides 25 feet of cable and an integrated wire-feed speed control.
As you would guess, the cost of such feature-rich guns escalates. For example, Miller Electric's Spoolmatic 30A lists for $1,200 but delivers a whopping 200-amp output with a 100% duty cycle, which means it can weld just about continuously.
But be warned. Not every spool gun is compatible with every make, let alone model, of welder. Many are configured to only work with a specific brand and model or require an adapter kit or control box to make them compatible.
For example, HTP's RSG200 only works with HTP welders. But you can opt up to HTP's RSG250, which includes a control box that can be installed on virtually any brand of MIG welder.