On Sat, 26 Jun 2010 00:07:52 -0500, Don Foreman
wrote:

On Fri, 25 Jun 2010 18:03:24 -0700, Gunner Asch
wrote:

On Thu, 24 Jun 2010 07:32:56 +0700, J. D. Slocomb
wrote:

On Wed, 23 Jun 2010 04:18:44 -0700, Gunner Asch
wrote:

On Wed, 23 Jun 2010 11:54:27 +0700, J. D. Slocomb
wrote:

On Tue, 22 Jun 2010 15:17:25 -0700, gunnerasch wrote:

On Tue, 22 Jun 2010 14:26:42 -0700 (PDT), stryped
wrote:

What is the thickest material a person can weld with this? I have co2/
argon mix and .024 wire, but can use up to .035 wire. It is a 110 unit.

1/4".

If you go to straight CO2..you can go up to 3/8', but may have to make
2-3 passes.

Gunner, who has a Weldpak 100 as a judge

I've never even turned a MIG rig on but can't you do the same as stick
welding and make several passes? Or does it have to be a single pass
sort of operation? Or, one pass is perfect, more is maybe?

Ayup.. you can indeed do multiples..but....the more layers you put
on..the more likely you are to get bad fusion of one or more welds. Its
of course best to do 1 base, where you are fusing the two base metals
with one single bead. Two more is pushing it..when you cant get enough
heat to fuse all 3 beads AND the base metals to fuze together. Its not
like glue, where you are sticking the surfaces together..welding is
intended to actually merge deep into the base metals. Oil field pipe
welding for example...they generally fuse the bottom of the groove with
6010 for deep penetration of both pieces of pipe, and then finish with
7010 for a clean, neat finish bead that doesnt hang on stuff, is smooth
and penetrates all three surfaces..both pipes and the top of the 6010
bead. Layers are ok..if you can get good fusion of the whole thing..but
with a smaller welder..they simply cant get hot enough to get fusion of
more and more metal as you add it. Chuckle..its a bit different than
using Silicone to fill in a groove or a crack. Which is what the issue
is when you are welding thick metals with a small welder. You are sooner
or later, going to simply be putting in a layer that might be
pretty..but really hasnt penetrated anything.

I learned that the hard way...with a spare tire carrier and a 110vt mig,
once upon a time. Its been mentioned here before a time or
two....cringe.

Gunner


You are wrong if you are saying that second and third layers on a pipe
penetrate completely through any existing beads. they don't. They do
melt the bead directly below the one being done sufficiently to fuse
with it but they do not penetrate, or liquefy, the entire previous
weld. And yes, I've welded enough pipe and had enough welds x-rayed to
know what I'm talking about here.

I've seen them welding the 2 inch thick flame shields, hanging over
the side of a cliff, at Edwards AFB and they were certainly not
achieving complete penetration through the entire two inches of weld
when they made the top pass.

You seem to be saying that you can do multi-pass welding with MIG but
you have to be careful to get fusion, just as you do stick welding??

Cheers,

John D. Slocomb
(jdslocombatgmail)

Not on 2" material.

Unless you have one BIG assed mig.

I disagree. I suggest that after thickness exceeds a fairly low
threshold, perhaps 1/8" in steel, more thickness doesn't matter
because there's enough thermal resistance between heat delivery site
and cold mass in that (and greater) thickness to allow formation of a
puddle in the workpiece with the power delivered by a small MIG. It
might take a bazillion passes to weld 2" to 2" but puddle-in-workpiece
= fusion = sound weld. Filler-puddle-on-workpiece = pretty-failure.

Penetration is only an issue for single-pass welds and production rate
with multi-pass welds. BTW, when I reviewed this viewpoint with Ernie
years ago on this forum, he concurred.

I'm not gonna mess with this while the lake is open water, but after
snow flies an experiment and demo might be in order. You supply the
test coupons, I don't have any 2" stock. I think I do have some 1"
bar.

Consider this: with successive passes, try building a "bead" 2" high
with your machine of choice. I can attest that I can do that with my
MIG because I did exactly that while conducting magnetic field
measurements before my ICD implant. I then put the base metal in a
vise and pounded the living **** out of the bead sideways with a 4 lb
hammer. It bent, but it didn't break or peel away. It was
effectively one globby chunk of steel growing out of the 1/4" stock I
started with.

There really can't be much discussion about it as arc welding has
worked that way since the beginning. In multi pass pipe welding, for
example, you may make three passes. Root bead, hot pass and cover.
None of the beads except for the root pass penetrates to the inner
surface of the pipe and an x-ray film shows the weld as one single
layer of metal with no indication of how many passes were made to weld
it.

Cheers,

John D. Slocomb
(jdslocombatgmail)