On Fri, 03 Sep 2004 00:44:12 GMT, "David Liles"
wrote:

What are the different types of welders? I found an arc welder for sale,
which I might buy. It would be mainly used for hobby work, and possibly
automotive work too.

If you don't know what the available types of welders are, you aren't
ready to buy one. You need to educate yourself a bit more...and
asking here is one way to do that of course, but getting training in a
class, reading some books, and doing some web searches are even better
ways. I know this is true, because I'm interested in the same
question myself, and have been working on it using those methods in my
spare time for a few months now (except the "take a class" one...don't
seem to be any around here at the moment).

Another responder listed the most common types available in the
electric welder class, but don't forget OAW (Oxy-Acetylene Welding).
It has some advantages over the electric types, as well as
disadvantages, but it's worth considering depending on your needs.
Having a torch around can be useful for cutting, heat treating,
bending, annealing, pre-heating, and playing noisy practical jokes on
unsuspecting victims...things you can't do very easily with any
electric welder. A OAW torch is also portable (i.e. no need for a
power source to plug it in). Most shops I've seen have one, even if
they also have TIG, MIG or other types around.

The various methods of welding (not all of which require a torch at
all...such as the thermite welding they use on railroad tracks on the
D.C. Metro system) all have their uses, and limitations. Buying one
without knowing ahead of time what you are going to use it for is like
buying a wrench without knowing the intended use. You could end up
with a nice ratcheting box wrench and actually need a pipe wrench.

My limited (so far) understanding says that it breaks down sort of
like this in the electric arena (happy to hear corrections from those
who know more if I've got any of this wrong):

Arc/stick welders: good for easy welding on steel, even fairly thick
steel, without requiring a huge amount of skill in most cases. Not so
good on thin (sheet) metal, or where a pretty bead is needed (you get
breaks where you have to stop to change welding rods). The sheilding
comes from flux, which you either dip the welding rod (which is also
the electrode) into, or have pre-coated on the rods, and this flux
will leave a glassy slag on the work which will have to be chipped off
afterwards. Not very useful for welding stainless, copper, aluminum,
etc., but they tend to be the cheapest form of electric welder.

MIG or "wire feed" welders: good for easy welding on steel, or, with
the right wire and gas combination, other metals, such as aluminum.
Used for things like welding exhaust systems, body work and light
structural stuff (up to about 1/4" thick). They are fairly easy to
use, and can come with a variety of capabilities, depending on price.
They start at prices about the same as a good arc welder, and go up
from there. Can be used with or without gas, depending on what you
are doing and what sort of wire you are using. With gas, rather than
flux-cored wire, you don't get slag, so cleanup is not required,
except for appearance. Probably the most common welders for auto work
or light fabrication and for hobbyists.

TIG welders: expensive, tricky to master (have to coordinate both
hands and one foot, all doing different things at the same time), and
the most capable of all. Can weld almost anything that can be welded,
including steel, aluminum, stainless steel, and copper. The arc
provides the heat, with the current controlled by a foot pedal, and
fill metal is added with the other hand, same as with OAW. The
electrode is not consumed by the weld (unless you screw up ;-). Some
fancy TIG welders are programmable so that current is varried exactly
as needed for startup, shutdown, and welding for the material being
worked on so you get a predictable weld every time...with a skilled
welder. The precise heat control can allow welding of very thin work
without as much heat distortion as you will get with stick or MIG or
OAW.

That's what I remember from my reading anyway. So far I've been
concentrating on OAW myself, with the electric stuff left for "some
day". OAW seems to be the most flexible system to start with, and the
skills developed will come in handy if I ever try TIG welding
(coordinating torch hand and filler rod hand while watching and
controlling the melt puddle to form a good penetrating weld). It's
also probably the cheapest way to start...though you can buy expensive
torches if you want to (like the Henrob/Dillon II). I figure that a
OAW setup will always be useful for something, even if I end up
getting a MIG or TIG later, so I started there. YMMV.

Good luck! Whatever you do, learn and practice the safety rules for
whatever you get. This stuff can kill you if you are unlucky and
careless, and will hurt you in lesser ways in a hearbeat if you don't
do it just right. Proper training, however you do it, is a wise move.
Half the stuff I've found so far never would have occured to me on my
own...(like all arc welders putting out strong UV, the vapors from
some metals and fluxes being toxic, and being sure to stand in the
right place when you first crack the valve on a high pressure tank of
O2...all seems obvious enough *now*, but it wasn't until I read about
it...)

-- Mike B.
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