Any experienced TIG alu-welders out there ?

[Peter Jack]

Me too. It should operate just like an accelerator pedal........ more pedal, more power.

Pete

[Gwillard]

Wow. That's a new one on me.
I don't think I've ever seen a pedal work that way.

[bak189]

The Tig unit pedal that is on the welder in the Netherlands worked like the one Octane has...........it got changed our real fast to a "Normal" one......down for more..........................................................

[Kato Engineering]

I understand that the "cycle rate" of a foreign electrical power in thru the wall socket connections is different. 50 cycles is common in most places other than america.   american power is 60. @ 220 or 208 volts.

  about the welder
the newer models produced have a secondary adjustment that you can change the high frequency rate and also the number of cycles that the pulsing of the power occilates.  this action enables the heat effected zone to be slightly narrower and more centered so that it is easier to continue a puddle. the alteration of the cycles of the pulsation also helps to clean the tungsten tip.

on my older hobart and linde units they have no mannor to change this cycle rate

my newer (2003) model miller dynasty inverter unit does.
when this feature is enabled/operational, it makes the machine HUMM with a high pitch sound.

[octane]

I see.
I do believe I have that:



The instructions says:
PULSE FREQUENCY CONTROL
at DC TIG , place DC/PULSE at PULSE,
this switch can adjust the pulse cycle frequency ( o.5-300Hz)

...and someone told me to crank it up like 100-120Hz ( + press PULSE switch )
to get a narrower 'beam'.
So I won't be able to use this welding alu , as it only works in CD mode right ..!? [EDIT: I mean DC ]

[Kato Engineering]

but on MY MACHINE,
this ONLY operates in A.C. mode.

are you welding aluminum in D.C.


I do not know any details about YOUR machine.

[Kato Engineering]

maybe  your machine, (i.e power supply unit)
has this ability to only occur during "ramp up" or innitial starting of the weld, so that it can make the heat zone narrower and more directed and  thus will not overheat a larger area.
kinda tied into the ability of the power unit to start at a certain percentage of what your maximum power/voltage is...when you innitially depress the pedal.
at least MY UNIT has that option, so that I can in fact have max at example 200 ....and the innitial start power when I first depress the pedal can be as low as 20 percent of the maximum...so that would then be 40 number.
but when it is at the 20 percent number, the power /flame/heated zone will be NARROWER and thus will be also more directed.
this allows the centered /directed heat to not burn off when you are doing inside corners or directed chamfers within a angle.
I am also one of those that have very good results putting a point on the tip of tungsten when doing aluminum...but only pretty much when under about 250 amps.
preheating aluminum to 150/300 degrees helps a lot.

[octane]

Thanks.
Sorry about my late reply.


The thing is that you kind'a lost me there.
I simply need to learn much more about what the hell I'm doing,
so I will start doing my homework by reading these two books that just arrived
from Amazon.



Hopefully I'll get wiser and able to understand the finers points of welding
to a point where I can actually understand what I'm told by folks trying to help me.

[tallguy]

I apologize for being so late to this thread . . . but for what it's worth, here is some
information that I think could be helpful/useful.

We already know that when it comes to welding aluminum, that cleanliness is
good.  But I didn't see any mention of cleaning the welding (filler) rods. 

When aluminum is extruded (such as in making welding rods), it's usually done with the use of a lubricant that is kinda oily/soapy.  If you pre-clean your welding rod(s) with a clean cloth dampened with clean solvent -- such as acetone, you will notice that the cloth ends up stained with dark marks.  That is stuff that you don't want in your weld puddle.  If you don't have a readily-available cloth, a paper towel would also work fairly well.  When working with something flammable -- such as acetone, please do it in a well-ventilated area, and not too close to where you will be welding.  Inhaling acetone fumes can't be good for anyone.  And you won't want to ignite those fumes with a welding arc.  Please remember to not leave the damp cloth/towel
lying around where you are breathing or welding.  Same with any container of the
solvent.

Regarding the ultraviolet radiation from a welding arc, please remember to never weld without using a nice dark viewing lens and gloves (cotton or thin leather is recommended).  Please remember that if cotton gets too close to the heat, the glove may start to burn -- with a glow, instead of a flame.  If not snuffed out, the entire glove may burn up.  Been there, done that.

Clothing that provides good shielding is also important.  I don't know how much ultraviolet "sunburn" or "arc burn" it takes to initiate skin cancer, and I don't want anyone to learn it the hard way.  I recommend a "bib" that attaches to the bottom of your welding helmet.  They are typically leather, quite soft, durable, and comfortable.  Yes, I learned from experience about arc burn. 

A gas lens in a GTAW (sometimes called TIG) torch is preferable to a solid copper
diffuser, and can provide a more uniform envelope of shielding gas, which can allow
for more tungsten stick-out.  Yes, a lot of varied experience can help you learn how
much.  You don't want to weld in a breeze, so don't use a fan blowing toward where
you are welding. 

Regarding the weld itself . . . most of the fillet welds (that is, those joining two
perpendicular pieces of aluminum) I saw in this thread appeared to lack penetration
at the corner, where the two pieces "touch each other".  So the welds were weaker
than they could have been.  An improved welding technique may have been
achieved by keeping the tungsten closer to the corner, and traveling more slowly
with the torch.

Aluminum is generally less ductile than steel.  This means that aluminum can't
stretch as much before tearing/breaking.  One of the things that makes aluminum
welding a bit more challenging/difficult, compared to welding of steel, is this fact.
And aluminum also has a higher coefficient of thermal expansion.  That means that
it expands or contracts more for every bit of temperature change, compared to
steel.  Due to these two limitations, aluminum is thus more prone to cracking of the weld when it cools/shrinks.  So I don't recommend "fusion welding" -- that is,
welding just by melting 2 pieces together without adding filler material from a rod.
Also, for the same reason, leaving a crater at the end of a weld is risky . . . because
it could initiate a crack.  And as we should know by now, a crack causes a "stress
concentration", which makes it easy for the crack to spread.  Don't believe me?
Have you ever bitten a bag -- such as a bag of potato chips -- in order to help start
a tear, so you could tear the bag open?  The end of a tear is a stress concentration,
making it very easy to continue tearing the bag.  Got it?  Good.  It's been said that
"a cracked weld is like NO weld".  Please don't make cracked welds.  Thaaank you.

It does take some practice, but is not really difficult to learn how to add a bit of filler material at the end, while easing off of the pedal that controls amperage (heat input).  In fact, a good "ending" for a weld should not be very deeply concave
at all.  Slightly convex results in a stronger weld.

Making a good, consistent weld can be greatly helped by having your hand (the
one holding the torch) resting on something, while slowly sliding the hand along
to make the weld.  Please remember that aluminum conducts heat pretty quickly. 
I have used a block of wood to rest my hand on.

One more suggestion . . . The oxidation of aluminum has already been discussed.
When starting a weld, one should use a clean end of a welding rod.  This means
that if the rod isn't full-length, that the end should be snipped to remove any
prior oxidation (due to having been melted in an earlier welding process). 

[tallguy]

Additional information . . .

Helium can be mixed with the argon, in order to (effectively) put more heat into the weld.  This could help when welding
thick aluminum, which notoriously conducts heat away from the location where you want the heat to be.  But helium doesn't seem to shield the puddle as well as argon does . . . (perhaps the helium "floats away" more quickly?).  It takes a little plumbing and thought, but one can connect two flowmeters to one hose that feeds the (mixed or single) gas to the welding machine's plumbing.  Then you can customize the mixture as much as you want.  About 20 cubic ft per hour of total gas flow was appropriate for most
of the TIG welding I did.  Most of the time it was for welding steel . . . using just argon, with no helium involved.

I re-read the entire thread of postings, and didn't see any welds whose "end" (the last part created) wasn't cratered . . . and weak.
Adding a bit more aluminum at the end, while decreasing heat input could help prevent a crater from forming.  Please remember
that aluminum tends to develop cracks from vibration.  One reason is that it "creeps" (a subject for a different time and place).
Another reason is that aluminum is not very ductile.  Cracks in welds are not our friends.  A simple idea to remember this is
"a cracked weld is like no weld".  Yes, I have made some cracked welds.  Yes, I have regretted it. 

The photo of the darkened tungsten electrode protruding from the torch suggests lack of shielding gas.  Yes, some things get learned "the hard way" (from experience, not from being taught by other folks).

Here's a little (basic) info about welding polarity.  When TIG welding on steel or stainless steel, normally the current is called
"DC straight polarity".  The electrons flow from the tungsten electrode into the metal workpiece, hitting/heating it.  And cleanliness isn't quite as important (although still desirable) as it is when welding aluminum.  If you reverse the polarity of DC current, electrons come from the workpiece, bursting out of its surface . . . and taking impurities such as dirt, oxides, etc. with it.  This has a cleaning effect on the workpiece, which is certainly good.  But all those electrons hitting the tungsten electrode will tend to melt it.  This is why DC reverse polarity is generally only used to "ball" the electrode -- to prepare it for later use in welding aluminum using AC current.  As you may already know, AC current is an oscillation between DC  straight and DC reverse.  This is a compromise in what gets heated, but during the DC reverse part of the cycle, this is when the aluminum workpiece gets cleaned. 

If you used just DC straight, you'd put the heat into the workpiece, with no cleaning effect on it.
If you used just DC reverse, you'd have a lot of cleaning of the workpiece, but not enough heat to weld.  You'd melt your
tungsten electrode.

Many modern welding machines -- such as a Miller Syncrowave --have a really nice feature that allows the user to "dial in"
the amount of DC straight (for desired heat) with DC reverse (for desired cleaning).  It's very impressive in its versatility.  But
it doesn't decrease the need for a lot of practice in welding technique . . . which involves control of amperage, position and
motion of torch, and position and motion of the welding rod.  Practice, practice, and practice cannot be over-emphasized.

Safety is also a huge and important concern.  I strongly urge you to NEVER TIG weld without wearing gloves.  A popular
material for gloves is deerskin, because it's thin and flexible.  But cotton is cheaper and comfortable.  It worked for me
for many years.   

Another tidbit:  The reason that you can't TIG weld aluminum to steel (or steel to aluminum) is because these two materials
are incompatible with each other.  It's because they have different coefficients of thermal expansion.  In other words (more
specifically), if you heat aluminum a certain amount (-- say by 100 degrees F), it expands much more than steel does with
the same amount of temperature increase.  And when cooling, a similar principle applies.  If you imagine a molten puddle
consisting of steel and aluminum, please try to think of this as being a weld.  I actually made this once, just to see what
would happen.)  When it cooled, it was a bunch of cracks in all directions.  Like the whole thing had totally shattered into
a million pieces.  The reason is that the aluminum shrunk faster than the steel, and ripped itself away from the steel.

Some materials (such as the element nickel) are compatible with steel, and alloy well with it -- improving its mechanical
properties such as low-temperature toughness.  But aluminum isn't one of them. 

Off the subject a bit . . . I understand that a plate of aluminum can be bonded/welded to a plate of steel by explosive welding,
which literally uses a high-powered explosion to force the two pieces together such that they bond -- on a microscopic level.
But I don't know how strong the resulting bond is.  It's very specialized, and rare -- not something one probably would use
on a racing vehicle such as a streamliner at Bonneville.

[Stainless1]

Tall..... you are the master of "late to a thread" but what's 16 years among friends   

[ronnieroadster]

 16 years between posts that's a while for sure. Let me add to this post to see if it can keep going for a little while.
Have a question about welding Aluminum to Steel. When ever I look at Crager mag wheels the centers are aluminum mounted to a steel rim. Looking at the back of those wheels it certainly looks like the two metals are welded together there's no other visual attaching type showing other than the bead from welding.
Ronnieroadster

[salt27]

I don't know this for a fact but I always assumed that Crager SS's had steel tabs cast in the aluminum centers that were welded to the steel rim.

[tallguy]

16 years between posts that's a while for sure. Let me add to this post to see if it can keep going for a little while.
Have a question about welding Aluminum to Steel. When ever I look at Crager mag wheels the centers are aluminum mounted to a steel rim. Looking at the back of those wheels it certainly looks like the two metals are welded together there's no other visual attaching type showing other than the bead from welding.
Ronnieroadster

There may be several ways to make something "look like" an example of aluminum welded to steel.  But I wouldn't count on
something like that being real.  By the way, there are other ways -- good ones -- to connect aluminum to steel (press fitting is
one of them).  There's really no absolute need to do it (or even try to do it) by welding.  You can do some research on this, as well as some physical experimentation -- like I did.  The results were a mess of hundreds of cracks in many places and many orientations.  It reminded me of something like putting a small piece of glass on an anvil, then smacking the glass as hard as
you can -- with a huge sledgehammer.  I don't think I can emphasize or describe this much more effectively.  But I urge you to
demonstrate this yourself if you have a TIG welding machine available.  The results are quite dramatic and memorable (to me).

[WOODY@DDLLC]

Stir Welding