Hi,
For general body work on British cars, you need more than a straight
wire-feed welder. You need a shielding gas, like MIG or TIG can provide.
MIG - Metal Inert Gas
TIG - Tungsten Inert Gas
MIGs are generally wire-feed units where the welding wire speed is
adjustable. TIGs require that you manually feed wire into the "puddle".
MIGs are considerably easier to use, as TIG requires a bit of practice to
get the technique down. TIGs primary advantage is that the heated area is
much more concentrated than MIG (which is fairly well concentrated in its
own right), so with TIG you can be even less concerned over warping.
However, with any welder you need to be concerned about warping owing to
the large temperature variations of the entire piece being welded.
The cheapo welders are generally "flux-core" wire feed. These make a lot of
heat at the weld site and are generally destructive in applications like
welding fine British steel. You can buy some of these kits with a MIG
conversion. DO IT.
As for gas, with MIG, use 75/25 (CO2/Argon) and get the largest bottle you
can. I bought a 60 cubic foot bottle and it lasts about a week of casual
body assembly. Anything smaller would last less than one project's worth
where a project == one or two welding beads... and you _know_ you'll run
out of gas on Sunday morning where you have the whole day for your project!
;-)
Last word about MIG - the units that are in the 125/130 DC AMP range (that
run on a standard 15 amp household circuit) are more than adequate for a
hobbyist. However, read the label on the "duty cycle" of the welder. Most
of the cheap-o welders have a 20% duty cylce. This means weld for 2 min,
rest for 8, weld for 2 and so on. This can be a pain in the butt in a big
job, but (as I said) is likely adequate for a hobbyist.
Personally, I have used a Miller 150 (not cheap) and a Lincoln 110 (also
called a MIG-Pak 10) with excellent results. The wire feed on the Lincoln
unit is touchy (I have to fiddle with it when I change the wire spool), but
not excessivly so. The Miller unit is awesome if you have the money, but it
is more of a professional unit and you'd have to do a lot of projects to
justify the more than $1k cost...
Another word - before you start a project like this, identify at least two
local sources for grinding disks, welding rod and gas. That way, you know
where to go when you run out. In my case, my primary source for grinding
disks and wire was the local Home Depot - came in handy a few times when I
needed welding wire at 10:00 PM... hey, I'm a "night owl" (probably to the
chagrin of my nieghbors, I might add).
So, figure on spending $600 min. for a MIG welding kit then get an angle
grinder and all the other stuff and have a ball.
Good luck!
rml
p.s. practice on some metal that does not matter to get your "technique"
down before you commit to welding your body... and to fully understand what
I mean about flux-core welders making too much heat - try laying a bead 1/8
inch wide by 2 inches long on a piece of 16 guage steel (with the flux core
wire)... believe me - you don't want to subject your car's body to that
kind of abuse!
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