I recently found a couple of rusted out spots in the passenger side
floorboard of my Jeep... I need to weld in a couple of patch pieces, I
guess... Unfortunately, the only welder that I have available to me
currently is a Lincoln "Tombstone" AC-225... My attempts so far have
resulted in either not being able to get the arc to strike or burning
through the metal... I've never had to work with this thin of metal
with an arc welder... The thinnest that I usually work with is 1/8"
thick... What is the recommended rod size and type for this sort of
endeavor? I'll probably end up putting one of the polyurethane type
spray on liners over it, so it doesn't have to be perfect, just not
terribly ugly... Any other tricks would also be appreciated...
I don't think you're going to get results from a stick welder that would
be as good as using some pop rivets. If you don't care about looks, pop
riveting on a patch and painting it with rust-inhibiting primer will be
easy and should last longer than the rest of the floor.
I do this sort of thing with an oxy-acetylene set, a hammer and a dolly.
But my training is old, and my trainer is older.
gas welding with oxyacetylene is what is used for thin sheet or
you might get away with the thin stick weld rods that are about 1.2mm
in dia. these are difficult to find in australia but are available.
I've used those with thin sheet successfully.
the amperage will be a lot lower than you might be used to.
use just enough amperage to get a start and try angling the rod a lot
more if you are getting blow throughs. it seems to moderate the action
to give a gentler arc.
thin stuff is always a bugger of a job though.
Tim is right; using a stick welder (AC especially!) to weld such thin sheet
is like trying to put out a forest fire with a screwdriver. You oculd
probably do it, but nobody is ever going to take picture. Pop rivets are
fine here. If you have access to MIG you can use the 'spot' technique that
works pretty well on all but paper thin sections but needs some practice.
If you absoultely insist on welding it with stick for whatever reason, start
with *super* clean metal. dont use a flap disk to clean it, youve got no
metal to spare here.... go with a wire brush wheel on a grinder, and go
light! turn down your stick welder to the lowest setting it will still be
able to strike an arc on (You *do* have neough OCV for your rods right?)
then try this somewhat spastic approach.... strike the arc by either tap
starting or match sticking it, then pull it back to the maximum length that
the arc can be maintained, then bring it very close to the metal then snuff
it out by either burying it then snapping it off, or just pulling it away
again. This whole procedure is done lightning fast! otherwise you burn
through as you have experienced already. chip, then repeat a few hundred
times. what happens is that slowly you build up a little bit of metal on
top of the existing metal to the point you can old the arc just *slightly*
longer than before. Eventually you can sustain the arc for a second or so.
keep going until you have welded what you want. Keep your wits about you
and maintain your patience; if you burn through, it will cost you big time!
If you do burn through, dont try to patch it up by welding on the edge of
the hole; you'll only make it bigger. start a ways back from the edge, then
build up to it. This takes a long time, so weld *very* small (like so small
you cant see any difference with each consecutive 'tap') otherwise you will
I have successfully (?) used this technique to weld exhaust pipes, and you
can get an air tight finish, but it will look pretty much like
aforementioned forest firefighting technique. Have also welded some little
things like fairing support brackets on crappy little mopeds and stuff when
stuck in the middle of nowhere in south east asia.
A big improvement on this technique is using a copper backing, if the
weldment has space for it. try to get a piece of copper as big as possible
and as small as necessary, but at least 1/4" thick of better. Put it in the
back the weld wont stick to it (much). welding this way is more like
And don't tell anyone I ever suggested welding like this
Grumman-581 wrote in article
Most REAL welding supply houses - not hardware stores, not automotive
stores, not Tractor Supply, Agway, etc. - have a 1/16" rod made especially
for welding sheet metal.
I have some based on 6013, and others that do not have an AWS designation -
but I know that they both work well on the sheetmetal that is found in
automotive body work.......because that is where I used them.
Again, go to a REAL welding supply house - one that specializes in welding
machines and welding supplies ONLY.
Eastwood (if they are still around) used to have a solenoid
contraption which used a very thin rod ( probably 1/16 ) and it would
rapidly pulse the rod forewards and backwards. It would make a series
of small tack welds along the weld line. I think it was limited to
about 45 amps and the gun was powered by the welder. It worked ok if
you could keep the rod along the weld line.
Just to add what Shawn said: Cut back to some solid metal, overlap the
new piece by about 1/4", clean well, back up with a copper (preferred)
or aluminum plate as a heat sink, and clamp it tight.. Use some 1/16"
6011 rod, practice on scraps to get the hang of it. Strike an arc, form
a puddle about 1/4" in diameter, stop the weld, wait a second or so
until the puddle solidifies, restrike the arc.
You're going to have a hard time with that welder. Most of the low-end
A/C welders won't hold an arc below about 35 amps, and you need a lower
amperage for thin stuff. If you could borrow a small mig welder from
someone, it would be easier to use than the buzz box. Also, the
Synchrowave 180 (and probably the Lincoln equivalent) have a
stabilization feature that allows them to hold an arc down to 10amps,
which is what you need in this case.
Advertise on Craigslist. Offer the temporary use of some of your other
tools for a welder that's easier to use.
A pneumatic flanger will help. It offsets the existing sheetmetal so the new
patch will be flush. Can't help you on the welding end, if you post to the
welding group, Ernie or one of the other guys may be able to help.