I can't stress enough how important a really good ground is to making good welds. I've known many certified journeyman welders that fail to verify a good ground before they strike an arc. When the weld doesn't go right(arc blow, porosity, sticking, poor appearance, heat fluctuation, etc), they blame everything except the ground. Many, if not most, of those problems will improve if you just take the time to verify a good ground.
Obviously, DC and AC current travel in a circuit. Anything that restricts or interrupts that circuit affects the quality of the arc. Your ground cable should be the same gauge as the electrode cable. Broken wires at the ground clamp reduce current carrying capacity. Ever see a ground clamp attached by just a few little strands of wire? That spot creates resistance. Resistance causes heat. Any heat that concentrates at that skinny spot is stolen from the electrode arc. Whether you use stick, MIG, or TIG, its all affected by ground. The reason the arc is hot is because the current is jumping across a small gap of air, also known as the arc length. The longer the arc length, the hotter the arc. That's why a stick welder will shorten his arc length when its getting too hot. The shorter arc cools the arc down. When the arc length is reduced to zero, the arc goes out and the rod sticks.
To verify a good ground keep your cables and connections in good repair. Do not rely on a ground through a metal table. Even if your table is grounded, put a clamped ground onto the work piece. Grind off paint and rust at the grounding point and at the weld. Wipe off oil and other contaminants. Don't use wet or contaminated rods or MIG wire. If your welding machine is grounded to the superstructure of a building or other structure, don't just put the spring clamp onto a rusty or painted column. Weld a 1/2" bolt to the superstructure in a spot that won't weaken the structure. Put an "eye" on the ground cable end and nut that eye to the bolt with a lock washer.
Last, but maybe most important of all, ground directly to the part that you are welding. This is particularly necessary when welding any part that moves in any way. Moving parts on a machine, vehicle, or other usually are only touching the rest of the structure through a bearing, bushing, hinge, slide, pneumatic or hydraulic cylinder, or some other connection that will be damaged if you run welding current through it. If you run weld current through a bearing, you will leave arc spots on the balls or rollers. That bearing is shot. Same with bushings and hinges and cylinders.
So, put a moment's effort into your grounds and things will go better.
Obviously, DC and AC current travel in a circuit. Anything that restricts or interrupts that circuit affects the quality of the arc. Your ground cable should be the same gauge as the electrode cable. Broken wires at the ground clamp reduce current carrying capacity. Ever see a ground clamp attached by just a few little strands of wire? That spot creates resistance. Resistance causes heat. Any heat that concentrates at that skinny spot is stolen from the electrode arc. Whether you use stick, MIG, or TIG, its all affected by ground. The reason the arc is hot is because the current is jumping across a small gap of air, also known as the arc length. The longer the arc length, the hotter the arc. That's why a stick welder will shorten his arc length when its getting too hot. The shorter arc cools the arc down. When the arc length is reduced to zero, the arc goes out and the rod sticks.
To verify a good ground keep your cables and connections in good repair. Do not rely on a ground through a metal table. Even if your table is grounded, put a clamped ground onto the work piece. Grind off paint and rust at the grounding point and at the weld. Wipe off oil and other contaminants. Don't use wet or contaminated rods or MIG wire. If your welding machine is grounded to the superstructure of a building or other structure, don't just put the spring clamp onto a rusty or painted column. Weld a 1/2" bolt to the superstructure in a spot that won't weaken the structure. Put an "eye" on the ground cable end and nut that eye to the bolt with a lock washer.
Last, but maybe most important of all, ground directly to the part that you are welding. This is particularly necessary when welding any part that moves in any way. Moving parts on a machine, vehicle, or other usually are only touching the rest of the structure through a bearing, bushing, hinge, slide, pneumatic or hydraulic cylinder, or some other connection that will be damaged if you run welding current through it. If you run weld current through a bearing, you will leave arc spots on the balls or rollers. That bearing is shot. Same with bushings and hinges and cylinders.
So, put a moment's effort into your grounds and things will go better.
