Well...auto-stitching isn't quite the same thing. Auto-stitching just
controls the on-off cycle of the welder as you move along your seam. So,
basically you start at one end and move along at some (nearly) constant pace
and the welder cycles on and off leaving short intervals of bead alternating
with gaps.
What I was describing looks like this:
)-------------| 1 |--------------)--------------| 3
|--------------)--------------| 2 |--------------)
where the dashed line is the seam you want to weld and the ) symbols are the
initial tack welds. Welds 1, 2 and 3 split the distances between the tacks
and are themselves tack welds, too. Then what you'll do next is:
)-----| 4 |-----)-----| 6 |-----)-----| 8 |-----)-----| 9 |-----)-----| 7
|-----)-----| 5 |-----)
splitting the distances again, alternating back and forth across the length
of the seam so that the heat-affected zones are as widely separated as
possible. The idea is that as you move from one end to the other, there is
some time for the metal to cool minimizing expansion and warpage. As the
spots get closer together, you should wait longer before applying the next
spot. Eventually what you get is a continuous weld composed of spot beads
that can be carefully ground down to slightly lower than flush for final
filling.
Auto-stitching, on the other hand, would attempt to do this in one operation
where the sequence would look like this:
)----| 1 |----| 2 |----| 3 |----| 4 |----| 5 |---)---| 7 |----| 8 |----| 9
|----| 10 |----| 11 |----)
The danger here is that if the amperage of the welder is high enough to
achieve good penetration, because you're welding in a linear pattern with
spots fairly close together, you run the risk of building enough heat in the
sheet to cause expansion and thus warpage.
--Arden
----- Original Message -----
From: <SFordRB@aol.com>
To: <sixtysixtiger@hotmail.com>
Sent: Friday, June 15, 2001 10:47 AM
Subject: Re: Welding
> Snap-On has a Mig that will do a chain or stitch weld which is what Arden
is
> talking about. Still think a TIG is the best alternative barring cost and
> learning curve. Miller used to have factory returns that were available
with
> a warranty....may be able to save some money and get a quality machine.
> Miller also attends as does Lincoln most of the N.S.R.A meets and usually
> gives great discounts. (make this my 10 cents worth)
>
> Sean "Dr. Moonstone"
>
> P.S. Now that I solved the days problems I'll get back to work (It's a
joke,
> don't get huffy anyone)
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