A few points that may be helpful as you get more familiar with the welder
you're using.

A mild steel wire is important, there are special grades of wire that are
really tough to grind away.
Lincoln SuperArc L-56 is a ER70S-6 wire, and I believe I found that it was a
mild steel wire when I looked it up.
The ER70xx designation is the majority of wire that I see at retail stores,
so it's very common.

Choosing wire with a bright finish has always worked well for me, even when
choosing fluxcore wire. I've known some guys that have had nothing but
problems with a fluxcore wire that had a dark appearance, almost as dark as
black oxide.

Putting the wire on is a lot easier than removing it.

I try to get the Heat setting a little hot, and attempt to move the tip
quickly, to avoid a lot of build-up of bead above the surface of the
sheetmetal (which is a very different method than making structural welds
with thicker, stronger parts).

A build-up/weld height of 1/16" may not look like much to remove, but it
consumes (essentially wastes) a considerable amount of time.

When grinding, the fastest removal of weld is accomplished with the very
edge of the abrasive wheel (like using a bench grinder wheel), not the
broader face, as would be appropriate for sanding.
With the edge of the wheel contacting the metal (grinder spindle parallel to
the metal's surface), the edge is continuously refreshed as material is
ground away.

--
WB
..........


"RogerN" wrote in message
m...
Got my welder out and practiced running some beads on 22Ga sheet then
proceeded to weld the patch panel in place where I cut out the rusted
metal. I had to do a bunch of tack welds until I got it solid, boy that
auto darkening helment is great, first time I ever used one. All these
little tacks and filling in holes with short bursts left me a good bit of
weld to grind. My patch panel didn't match up perfectly at a bend so I
tacked the top and then finish formed the panel in place, it didn't need
to be perfect but did need to be below the surface to be built up with
bondo.

After welding and grinding I built up with bondo and inline sanded, built
up with bondo again, inline sanded again, and a couple times again! I had
to weld up a thin place in the metal that showed up when trying to inline
sand the repair flat. The last time I bondo'd I didn't use quite enough
hardner and maybe it will be ready for sanding tomorrow after work. The
previous time I bondo'd it started looking real good, sandpaper made
contact with the whole surface except an angled part I think will take
some hand work.

At first I set my welder to feed about 10" of wire in 6 seconds, I saw
this recommended to set 100"/min feed for auto body welding with 0.023"
wire. My preliminary heat setting caused surging, the wire would start an
arc, burn back too far, stop, and repeat. After some trial and error I
found out turning the heat down a little more gave me a more continuous
weld.

At first attempt it seems my Century welder should do the job for auto
body welding. After some more practice I would like to go to the Lincoln
dealer and see if they have a Power Mig 140C demonstrator I could try and
compare it to my old Century. I see what you guys mean about the
continuous heat adjustment, I was able to fine tune the heat and wire to
run a nice bead, but the adjustments were tiny.

RogerN