Here then are some of the more common welding mistakes and how to rectify them.
Lack of preparation
A strong weld needs a good foundation and a rough, cracked or dirty surface isn't it. Welding over cracks is about as effective as papering over them – they'll still be there to keep on cracking and create a weld of hurt later. So grind them right out. Likewise rust, old flaky paint and dirt. Take the time to completely remove them until you have a clean, uncontaminated surface and your weld has every chance of success.
The wrong metal
A good weld will always test your metal and if that metal is overly worn or too thick, it will probably fail. Welding weak metal is like giving a 90 year old a bionic knee; it's simply not going to solve the problem. If your metal is fragile or fractured, forget it or reinforce it. Also watch out for metals more than ¼ inch thick if you're planning to do your weld in one flourishing pass. Cranking up the current won't help either no matter how slow you go. The filler metal won't bond and it will be goodbye cruel weld. If you're going to use thick metal, weld in multiple passes.
The wrong current
Too little and your weld won't hold. Too much and you may well burn right through the metal. If you're welding a particular metal for the first time, your welder's guidelines should tell you what current to use. It's also a good idea to cut off a few scraps and test your settings on those. Otherwise it will be the end of the weld as you know it.
Bad electrodes
If you're trying to use a moist electrode for stick welding or a MIG wire with oil or rust on it, you're wasting your time. Only use clean MIG wires and keep all electrodes warm and dry in a proper electrode storage oven or heat them up before welding.
Bad technique
Losing your place on the weld is a common mistake, especially if you're wearing an old fashioned flip down face shield. Here's the trick: get your hands positioned so you're ready to strike your arc and start welding. Flip your face shield down with a brisk nod of your head and strike your arc right beside the joint you're welding.
And while this may not yet be an exhaustive guide to welding mistakes, I've run out of bad puns.
