Our last foray with Metal Inert Gas (MIG) welding—which, by the way, is generally a misnomer for GMAW (Gas Metal Arc Welding), but it’s so commonly used, we’ll continue to do so—will be a general overview of its application with aluminum. Yes, that’s right, MIG welding aluminum … with Miller Electric Mfg. Co.’s Spoolmate 100 Series wire-feed spool gun. (The Spoolmate is not limited to aluminum, as it will also accommodate mild and stainless steel.)
For those of you gun shy about learning to TIG weld (a topic we’ll begin covering next month), but would like the ability to weld aluminum, the Spoolmate 100 MIG accessory—compatible with Millermatic 140/180/211 and Passport Plus machines—may just be the perfect solution. For one, the investment is a fraction of the cost of a complete TIG welding setup—new or used. Secondly, you don’t have to learn a whole new welding process (that is, if you’re proficient with your MIG welder in the first place).
The Spoolmate is a direct-connect accessory (a retrofit kit is required for pre-AutoSet Millermatic 140/180s), meaning all you do is swap out your MIG torch for the spool gun and hook up the appropriate shielding gas. It’s as easy as performing the process itself. The gun features a recessed contact tip and a clear spool cover to help reduce the number of burn backs (which is when the wire burns back and melts to the tip, ultimately ruining it). Another great feature is a pair of dual V-knurled drive rolls that help ensure consistent feeding of aluminum, which lacks the column strength to reliably feed through a standard MIG gun. Users can also adjust drive roll tension to match the wire being used.
The Spoolmate is great for hobbyist-type work—it’s affordable, easy to use, and can handle a good variety of jobs. However, when it comes to welding thinner materials, or for more than just occasional use, as you’ll see in next month’s Metal Shop, you still may want to consider stepping up to TIG welding.
Miller’s Spoolmate 100 Series spool gun is rather compact considering it’s a wire feeder in itself! It’s also quite ergonomic, and can accommodate 0.030-0.035 aluminum wire and 0.023-0.035 mild steel and stainless steel wire.
6 & 7. There are two types of general filler metals (wire) for welding aluminum with the spool gun: 4043 and 5356. For our uses, 4043 is best suited/recommended. Installing the wire reel is very straightforward. With the see-through cover off, hold the drive roll release lever down while feeding wire through the inlet guide.
8 & 9. With the contact tip removed (just as you would with a standard MIG gun), thread wire through with just enough stick-out to re-install the tip and nozzle.
10 & 11. The Spoolmate gun is factory-set for proper 0.030-0.035 aluminum wire pressure. To ensure proper drive roll pressure, with the tip/nozzle installed and your machine powered up, feed the wire directly into a block of wood, as shown, and using a flat blade screwdriver, adjust tension accordingly with the recessed screw directly in front of the release lever.
