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On welding machines.....Hi frequency start ( common on the better machines
) is best, but continuous hi-freq. is bad for you without some shielding. RF
radiation gets to you, and is difficult to shield against.
As for skill, TIG welding is easy to learn, and generally pretty forgiving.
But it is slow, and can overheat the weld zone if not done right. I like to
do root welds with a TIG machine, and then wire feed ( MIG ) the cover
passes. Cleaning all the start/stop zones before continuing is essential. Grind
them out to expose bare metal before running the next bead. Use shielding gas on
the back side of the welds, to prevent and gas pockets. Or you can grind the
weld backside after you're done and run a cover pass on the inside of the
hull.
There are dyes you can apply which will show most pin holes, and these can
be drilled out and re-welded.
Some materials require pre-heating, and post heating. Usually done with a
torch and thermal blankets.
There are some companies that have stress relieving ovens large enough to
put the whole thing into after all the welding is done. I expect it's
expensive.
Stick welding machines ( DC for steel, AC for aluminum TIG) are not
compatible with Mig, but a simple TIG torch can be plugged into a stick machine.
You can get a simple TIG torch and hose for about $100 and a flow meter and hose
for another $150/$200. Add a bottle of gas, tungsten tips, regulator, and
miscellaneous stuff, and you're looking at a minimum of $600.
MIG ( wire feed ) is useful for almost all welds, is easy to learn, good
for out-of-position welding like vertical and overhead, and when gas shielding
is used, can produce a TIG like weld with practice. I've never had a problem
getting into corners or tight spots with the MIG gun.
The heat applied to the weld zone is minimal when using MIG. If you are
going to have one machine, it should be a MIG. Miller makes the best ones, but
Lincoln is ok too. Hobart is crap. Frank D.
Stick welding requires more skill than TIG or MIG.
A gas drive welder is portable, but the pulse of the gas engine makes it
difficult to produce very fine welds.
Not really suitable for TIG applications when a critical weld is
needed.
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