I'm TIG welding a .625" dia cylinder to a piece of .125" flat stock.
Both are stainless. Welding the two pieces together is not a problem
in and of itself. However, I'm having difficulty getting the final
bead to be anything less than about 1/8" to 3/16" wide. This
relatively large weld is somewhat unsightly. I would like to get the
bead down to about 1/16" wide (or less). I'm using a #4 cup on my TIG
handle and have tried both 1/8" and 1/16" electrodes I'm sure
technique must play a part. I've tried filler rod ranging from 1'16"
down to .035" wire. The problem seems to be that I can't get my puddle
small enough. As soon as I add filler, the bead jumps to a width well
over my target size.

I have a similar assembly that was TIG welded (by an unknown source)
with bead widths of just about 1/16" wide (see attached photo).

Any suggestions would be greatly appreciated.
Dan

Sorry about the attachment not being readable. Please see my pic in
the metalworking drop-box under the title "Tiny TIG Welds". Thnx.

Sorry about the unreadable attachment. Please see the picture in the
metalworking drop-box under the title "Tiny TIG Welds"

Dan,

30 years ago when I had way better than average vision, I was capable of
laying down 1/32 wide fillet welds on thinner materials. IIRC, the
filler was .020. This was while working at NASA in a work exp. program.
That filler may have been custom drawn, I've never been able to find
anything smaller than .030 since then.

Anyway, you need to get the tip of the tungsten right down close to the
material to keep the puddle size down. Like within .010-015. This
requires great manual dexterity, eye sight, and hand-eye coordination.
It's been a long time, but I sorta recall stabbing the rod into the very
leading edge of the puddle and getting it the heck out. You don't want
to melt a drop of metal off the rod and into the puddle, there's no room
for that. You want to just get a little bit of metal to melt off the end
of the rod and flow into the puddle. It's also slow going! If you're
just after appearance, time isn't an issue. But if you're trying to
minimize heat, you can easily input more total heat by welding slower.
Oh, might also try a longer taper on your tungsten, and make sure your
grind marks are axial (aligned with the axis of the tungsten rod).

Tiny fillet welds are not easy and will probably require lots of
practice. That was the nice thing about that work exp. program, I had
the best of everything to learn on, and almost time and materials to
practice to my heart's content. Not to mention some of the most talented
"crusty old fart" welders I've ever seen...

No, I could not even hope to duplicate that sort of welding today. Even
with glasses and/or magnifying lenses, my eyesight just isn't up to the
task anymore.


Jon

DanD wrote:
Sorry about the unreadable attachment. Please see the picture in the
metalworking drop-box under the title "Tiny TIG Welds"

I think I could do better than this. I'm no expert, but I do have
a good machine, and that helps. I've got a Lincoln Square Wave TIG
300, and it can be turned down to incredibly low current, about 5
Amps. I have actually done some welding with the HF, before the main
arc started. Use the smallest rod you have, with a very sharp point,
to keep the arc very narrow. A gas lens may allow you to get good
shielding with the electrode sticking out farther than usual, so
you can get in to the angle. A very close fit-up between the parts
will be a big help. The lower thermal conductivity of stainless
will help keep the puddle small. No question that practice will
make this work better. You may want to make your own filler
material from the stock. You can take lathe chips and pound them
into a rough wire, and feed with tweezers or something. That way,
you can make the filler as fine as you need it. You can also
get stainless wire in a variety of alloys, and down to small
diameter.

Now, with all that said, if you are trying to get a full-depth
fusion weld, it can't be done with a bead narrower than the material
thickness. So, a very small bead implies a shallow weld, unless
you use electron-beam welding.

Jon

You didn't mention the thickness of the cylinder. There's no way you'll
get full penetration in 1/8" with a tiny bead, but if the cylinder is .030
then full penentration makes no sense anyway.

You don't need a fancy welding machine to do this. I'd use a gas lens, and
given the thickness of the plate I'd start with an autogenous weld -- no
filler at all. Just fuse them together. You won't get a fillet that way,
but you can get a sound weld.

If you must have a small fillet, then I'd still think autogenous -- fusing
the parts together with heat focussed primarily on the thicker part, and
then dabbing .030 or smaller wire into the puddle (but not directly under
the arc) to get the cosmetic fillet. You make a puddle, whip the arc away
and dab quick to add just a bit of filler, return with the arc and move
forward a bit, and so on. If you're careful, you'll get a tiny stack of
dimes -- well, maybe .05 cent coins.G I'd need at least 2X
magnification in my mask to do this. Your eyes may be better.


"DanD" wrote in message
...
I'm TIG welding a .625" dia cylinder to a piece of .125" flat stock.
Both are stainless. Welding the two pieces together is not a problem
in and of itself. However, I'm having difficulty getting the final
bead to be anything less than about 1/8" to 3/16" wide. This
relatively large weld is somewhat unsightly. I would like to get the
bead down to about 1/16" wide (or less). I'm using a #4 cup on my TIG
handle and have tried both 1/8" and 1/16" electrodes I'm sure
technique must play a part. I've tried filler rod ranging from 1'16"
down to .035" wire. The problem seems to be that I can't get my puddle
small enough. As soon as I add filler, the bead jumps to a width well
over my target size.

I have a similar assembly that was TIG welded (by an unknown source)
with bead widths of just about 1/16" wide (see attached photo).

Any suggestions would be greatly appreciated.
Dan

Have you considered Silver Soldering ( brazing ).
I can see wanting to have the skill to TIG it, but silver soldering
could be a better method for production.

Dan

Jon Anderson wrote:
Oh, might also try a longer taper on your tungsten, and make sure your

Nope. Just the opposite. I know it's counter intuitive but a shorter
taper gives a narrower arc. Try about an 80 degree included angle on a
0.040" tungsten. I think 0.020" diameter aircraft safety wire is
available in several SS alloys.

Ted

"Ted Edwards" wrote in message
news_5df.138375$Io.63608@clgrps13...
Jon Anderson wrote:
Oh, might also try a longer taper on your tungsten, and make sure your

Nope. Just the opposite. I know it's counter intuitive but a shorter
taper gives a narrower arc. Try about an 80 degree included angle on a
0.040" tungsten. I think 0.020" diameter aircraft safety wire is
available in several SS alloys.

Ted

Ted is right, I read a tech. article about electrode point angle and
penetration and bead shape. It is just the opposite of what it seems like it
would be. All the tests were done using a machine to elim. human variables.

Dixon

Ted Edwards wrote:

Nope. Just the opposite. I know it's counter intuitive but a shorter
taper gives a narrower arc. Try about an 80 degree included angle on a
0.040" tungsten. I think 0.020" diameter aircraft safety wire is
available in several SS alloys.

I always ground longer tapers when I wanted smaller, finer welds. But
just because I made it work doesn't make it the best approach.
Yeah, thinking about it, I think I see how a shorter taper would give a
smaller arc.

Though thinking back (my TIG welding is approaching a decade in my
past...) I didn't carry the really shallow angle all the way to the tip.
I'd shape it that way, then put a very very small, shorter taper right
at the end. So really was going almost a combo.
Too fine a point just doesn't hold up, which is why I went to a double
angle.



Jon