Gunner wrote:
I just got back in from trying out some of the settings on some 1/8"
alum plate. I managed to get a decent butt weld on two of them..which
developed a hairline crack right down the middle of the weld line. No
filler was used. I take it that I have to always use filler with
aluminum, unlike steel?
Yep. Most aluminums are characterised as being 'hot short'. Which is an
obtuse way of saying they really need to have filler added when being
welded. What rod are you using?
The next butt weld on the other side was with
filler and it didnt crack, though it looks pretty hokey..which is
strictly operator error. I get some black "soot" on the weld. Is this
the result of me burning the alum due to too much heat or something on
the filler rod?
Most likely cause of the soot is a dirty surface or a contaminated
tungsten. Surface and rod need to be cleancleanclean. Scratch clean with
stainless wire brush or scotchbrite or file, follow by an acetone wipe.
If the tungsten is contaminated, either from being dipped in the puddle,
touched by the filler rod or, my favourite, sucking up the blob of rod
you just deposited on the weld area, it'll need to be reground to fresh
tungsten.
Pretty tough stuff to get off, had to use a SS wire
brush. Wow..there is a narrow heat range between getting a puddle
and melting a hole in the thin plate..much much more difficult to
judge than steel. Im still not sure what is the best settings to use
with the pulse stuff, though after you folks explainations..I can see
Stuff happening now.
Other things to keep in mind. Keep Tungsten and filler rod about the
same thickness as the material you're welding (for thinner stuff). About
1 amp of current for thou of material thickness. (125 amps or so for
1/8") The closer you start with the max current setting the easier it is
to control things with the pedal. Trying to weld at 60 amps with the max
current at 250 amps is tougher than it needs to be.
--
__
Pete Snell
Royal Military College
Kingston Ontario
The reasonable man adapts himself to the world;
the unreasonable one persists in trying to adapt the world to himself.
Therefore all progress depends on the unreasonable man.
- George Bernard Shaw