Working the Mig weld Bead
Yes Bead itself needs to be stretched as my friend Chop is saying.
The idea that is trying to be duplicated is shown in this Video. Keep in mind this is a Technique called Hammer welding done with Gas which has the softest weld bead of the three welding techniques. But the idea is the same.
https://www.youtube.com/watch?v=Rv5bKXJ3kEMWhen I am gonna stretch a Mig weld bead I have had better luck Grinding away most of the weld bead away first then stretching it Hammer on Dolly as Chop explains.
Care must be taken not to overstretch.
As well great care must be taken to stretching evenly!
A panel as large as this will begin to distort as welding progresses as well as when you start stretching the Beads avoid the urge to start working Dolly off hammer trying to straiten panels till all beads have been stretched evenly IF you work the stretching evenly the panel will settle down and straiten itself.
Working off Dolley to soon can lead to all sorts of problems such as Oil canning.
When your repair panel fit up has Zero Gap fit up before welding you give the bead very little room for shrinking of weld bead, As welding progresses the panel starts to distort due to the weld bead shrinking the two pieces together showing you the need to stretch the beads to get the panel to settle back down. When their is a large Gap between the two panels the shrinking is greater and the distortion is greater.
Dennis B.
A&P Mechanic, FCC General radio Telephone Operator
Line Maintenance A&P Mechanic and MOC Tech specialist.