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Re: Question about TIG

To: Brandon Dixon <dixon@cs.ua.edu>
Subject: Re: Question about TIG
From: Steven Shipley <shiples@home.com>
Date: Thu, 27 Jul 2000 19:23:08 -0700
Brandon Dixon wrote:
> 
> These are all very good points, and I'll add one more idea that I thought
> that some of the more experienced TIGers would suggest:  It sounded to me
> like you were welding on sheet metal on a vehicle.  It is quite possible to
> get contamination of the weld pool from the BACK side of the metal.  Any oil
> or grease or undercoat, etc back there can mess things up big time.
This truck has some serious corrosion.  I don't expect to be able to
weld over
rust so I grind it clean.  But I suspect that I may be running into
contaminants
that are below the consmetically clean surface.  If the weld puddle is
as
sensitive to oxidation as Bill says, it sounds like a definite
possibility
is contamination and it may be my welding technique that is bringing it
in.
Insufficient preparation could be a contributing factor as well.

Thanks to all who are contributing to this discussion.  There's a lot of
variables to consider in this process and they're not all installed in
my
head yet.  

Steve Shipley
> 
> Brandon Dixon
> 
> -----Original Message-----
> From: Bill Ruof [mailto:1953xk@home.com]
> Sent: Thursday, July 27, 2000 8:22 AM
> To: Steven Shipley; shop-talk@autox.team.net
> Subject: Re: Question about TIG
> 
> I have to add my two cents.
> 
> Spatter is little BB's of metal.  If you are getting a buildup of small
> discrete balls of metal one possibility is that you are overcooking your
> weld pool.  The arc and the weld pool should be very smooth.  No sparks or
> flying metal.
> 
> Take care not to contaminate the tungsten.  Once you dip it in the weld pool
> or jam the filler against it you've contaminated it and you will start to
> get a buildup and degradation.  Snapping off the contaminated part is OK but
> you still want to grind to shape it.  It is best to grind with a freshly
> dressed wheel.  Make sure you have a good point to start.
> 
> Folks were also dead on the money about being sure that you are using the
> right filler.  Gas fillers have LOTS of deoxidizers and result in an
> overactive weld pool if used for TIG welding.  Trim your filler after a stop
> and make sure it stays under the gas shielding while you're welding.  If you
> pull it out from the shielding while you're welding it will oxidize.  When
> you run that oxidized metal in, you destabilize the pool and the arc.
> 
> The base metal probably isn't the problem if it is ground to bright metal.
> You have to make sure to get out any pitting too.
> 
> If all else fails recheck your gas lines and fittings to make sure you
> aren't drawing in any air along the way.
> 
> Welding is SO much fun.
> 
> Bill Ruof
> 
> > I've encountered a problem.  I keep seeing a build-up of spatter
> > that sticks to the electrode and the ceramic cup.  As this spatter
> > builds up the arc becomes harder to control.  I'm spending a lot of
> > time putting new points on the electrodes.

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