In the Shop
As a farm machinery mechanic and writer, Dan brings a hands-on approach that only a pro can muster. Along with his In the Shop blog, Dan writes a column by the same name as well as the Shop Series for Farm Journal magazine. Always providing practical information, he is a master at tackling technical topics and making them easy for all of our readers to understand. He and his wife, Becky, live near Bouton, Iowa.
MIG Welding On Big Equipment
Jan 13, 2010
MIG welders are great for farm repairs, but have one downfall: their ground cable and welding hose/cable are often less than 10 feet long. That makes welding inside combines or on the inner frames of big tillage equipment difficult.
The problem is that it's difficult to "push" wire from the spool in the welder through more than 10 or 15 feet of wire guiding-hose. An alternative is to use a spool gun attachment to extend the reach of the MIG unit.
Spool guns have 20 or 30 feet of cable/hose to feed power and inert shielding gas to a gun-like assembly. A small 5-pound roll of welding wire is spooled on the rear of the gun, and the gun's trigger activates that spool to feed wire during welding.
Spool guns are commonly used for aluminum welding, since it's difficult to push soft aluminum wire very far. The spool gun I've been using is a Miller Spoolmatic 15A hooked to a Miller 212 Autoset MIG welder, spooled with .025 steel wire rather than aluminum wire. We rigged our regulator with a T-valve so we can supply gas to either the 212's regular .035 wire gun, or send gas to the spool gun's nozzle. That lets us use the "big MIG" for most of our welding, and the spool gun for long distance welding.
One concern with using a spool gun to weld on big equipment is that the welder's ground cable is still only 10 feet long. So the potential for shorting or "spiking" power through any computers or circuit boards on combines, sprayers or tractors is increased. Disconnecting the ground cable from the battery is one solution, but annoying and time consuming. I'm experimenting with a little gizmo called a "Zap-It" that's supposed to prevent surges and spikes to computerized components. The theory is that if I hook the Zap-It to the battery terminals I can have the ground connection 50 feet from where I'm welding on a piece of machinery without worry that I might surge or spike an on-board computer. I'll let you know how it works.
Otherwise, I'm very impressed with the potential of adding a spool gun to a traditional MIG unit. It's not cheap, but convenience often comes at a price.