Which welding problem is commonly caused by excessive drive-roll tension, tangled wire, a clogged gun liner, or too small a contact for the wire diameter?

• A. Bird nesting
• B. Porosity
• C. Burn through
• D. Distortion

Answer: (A)

Bird nesting is being tested here—the problem happens when the wire feed into the gun isn’t able to move smoothly and instead folds back on itself inside the drive system or liner. When drive-roll tension is set too high, the wire is pinched and buckles. If the wire spool is tangled, or the gun liner is clogged, there’s extra resistance that the motor can’t overcome, so the wire backs up and forms a tangled nest. A contact tip that’s too small for the wire diameter adds back pressure, pushing the wire against the liner and contributing to the jam. These feed-path issues create a classic nesting of wire rather than defects like porosity (gas issues), burn-through (excess heat or thinning), or distortion (warping from heat). To prevent it, set the drive-roll tension so the wire feeds smoothly, use clean, straight wire, replace a tangled spool, clean or replace the liner, and match the contact tip size to the wire diameter.