Richard,

Do you know of a good source for the .023 wire for 4130? Do you use the
normal 75/25 mix for the shielding gas?

--
Have a good one!

Steve
www.americanspiritppc.com
"spektr" wrote in message
...


Richard.

The basic problem with Mig welders is the inability of the operators to
set
them up.
As delivered, most home style 110 mig boxes are set up to use .035 wire.
The idea is to have a box for mild steel, cars trailers shovels etc......
Smaller wire
sizes are available and needed for thin wall applications. Use .023
instead
of .035.
Excuse me slaughtering exactly correct terms here, but the arc intensity
is
a
function of the area of the wire. So heat control in BTU/Min is easier
with
smaller diameters.
That means that the current carrying capacity of the smaller wire is 66%
of
the .035 and
that go's a very long way towards making the job work.

For good fusion, the larger wire needs a btu/sec heat rate that in many
cases exceeds
the base metals "pour point" or the point where id is completely liquid
and
flows away
from the weld. Using smaller wire gets the heat rate more in line with
the
tubes fusion heat rate.

Scott Correa

"Richard Lamb" wrote in message
...
A/O rig will cost as much as a good MIG set, but is a better choice
for welding thin wall 4130.

On the other hand, it's a lot easier to tack with the MIG since it
only takes one hand.

But if you are building a steel tube airframe, you are going to need
a good torch to weld on a thousand little tabs and such.

Either technique will require practice.

Richard

PS: Thank Barnyard for the link to WinMitre.
Very handy little tool there.