Hi all :)
I have an older Lincoln AC 225 stick welder (220 v), that works quite
well. I would like to invest in a Tig torch set, flowmeter, and bottle
of argon to do some light to medium duty heli-arc welding with, using
the Lincoln welder as the power supply.
It would be mostly sheet metal, and up to 1/4" max thickness for
Would this be a practical setup? I can't afford a dedicated Heli-arc
welder, with all the bells and whistles, so I'm wondering if this
would be a do-able compromise.
All advice welcome :)
You would probably have better luck with a DC welder using reverse
polarity (IIRC) for aluminum, than AC without a High Frequency supply.
The High Frequency allows the arc to stay lit while the AC current
cycle back and forth across the zero line.
High frequency add on boxes for larger welders come up on ebay, but at
prices that start to make a low end TIG setup affordable.
IMO, unless you have a talent for electrical circuitry, you will waste
less of your time and money by going straight to the real thing, rather
than dicking around trying to make the stick welder be what it isn't.
On the other hand, at least one of the guys here has converted a heavy
duty power supply to an all singing all dancing AC/DC/Pulsing/Plasma
Cutting and everything else welding machine. Out of the league of the
likes of me, though.
Hock your first born, take out a 4th mortgage on your house and car but get
a good TIG machine. I've got a real good Miller stick welder that came from
a College welding department. I hardly ever use it now that I have the TIG.
Now that I'm getting used to my Plasma cutter, the TIG and the Plasma Cutter
have a permanent home and will be the last tools to leave my shop. My
Acetylene torch set up is relegated to brazing and heating only.
What you propose is doable.....my son and I converted the same AC
buzzbox into a simple but fully functional TIG welder which is used to
fabricate stainless steel exhausts for the family fleet. We have
tested it on aluminum and copper, using pure argon cover gas, and
junior sez it works like a charm. The visual inspection and
mechanical tests by me bears this out.
To do the conversion you ought to be familiar with power electric
wiring, and a modicum of electronics experience. Here is why:
You will need to convert the AC welder to supply DC current. This is
achieved by means of a full-wave bridge rectifier capable of handling
say 220 amps at 350 volts.
The DC must be filtered by means of a choke or inductor. The size of
the inductor is about the same as the welding transformer and handles
the full DC welding current. The inductor is needed to keep the
current flowing when the DC voltage drops to zero during the
rectification cycle. This is particularly necessary for low current
For light gauge welding and Aluminum (with AC) you require an arc
starter. These are surprisingly simple....we built ours from scratch
using an oil burner ignition transformer and broken tungsten carbide
endmill shanks, among other electronic stuff.
To weld thin material, especially copper and aluminum, but handy for
all thin metals, you require on-the-fly current control because the
arc is started with a relatively heavy current and once the welding
pool has formed the current is reduced to prevent melt-through. Not a
difficult circuit to build, same for the foot pedal, but some
knowledge of electronics is required.
As Trevor stated it is easier and faster to begin with known DC
equipment. Conversion of AC welder to DC can be fraught with
expensive lessons when you marry the HF arc starter to the
If you are still interested in pursuing this let us know and I can
help you on your way. If you have the AC welder and are good at
scrounging the costs are not too steep. Just be prepared for some set-
backs manual labour.
Several here have purchased this rig, and like it.
Goes on sale regularly for $199
Where are you located? I occasionally run across older tig machines
"Liberalism is a philosophy of consolation for Western civilization as it
- James Burnham
I made two seperate "Heliarc welders" in the 1960s. I used my AC buzz
box stick welder for one. The stick welder with the HF and TIG torch works
very well for melting aluminum. If you are Very Good, maybe you could
actually weld with a home made conversion, add -on to your Stick welder if
the metal is thick enough. I used mine for "welding" thick aluminum and
"light alloy" VW cases, and Corvair heads..
My observation is -- Build your own TIG if you want to laern about how
to build TIG welders. Buy anything that fits your budget if you actually
want to TIG weld.
I'd be happy to share any of my experiences with you if you decide to
build a TIG add-on to your Stick welder.
I'm curious. How does it regulate the current? Do you regulate the line
voltage going into the box with a light-dimmer like circuit? Or do you
somehow regulate the high amp current after the transformer?
First off; a big Thank You! to everyone who replied. The depth of
knowledge and experience in this NG is fantastic :)
Secondly; I have decided to hold off until I can afford a dedicated
rig, even a low-end one if necessary, but not necessarily a low-end
I'm no electronics whiz, altho I can do basic wiring no problem. But
by the sound of things, I would be further ahead to buy a proven
factory-made unit rather than trying to cobble something together with
my level of knowledge and experience.
Once again, Thanks Everyone, for the advice!
For current control we designed a triac phase control on the primary
side of the transformer. The tricky part was to get regulation that
was wave symmetrical (important for transformer application) and
hysteresis-free for fine current adjustment. The potentiometer we put
into the foot-pedal. The triac can handle 600VAC up to 40 amps, and
has been trouble free. The tig torch is rated for up to 150 amps so I
doubt we will exceed the 40 amps of primary current.
Our intent was NOT to discourage you, but to let you know what you are
in for! We would be pleased to share our experience with you.
Start by picking up a 220 V transformer the size of the welding
transformer in the buzzbox, or a little larger. Next you need cable
to wind about 36 turns onto the transformer core, after removing the
existing windings. We managed to salvage the wire we took off and,
by cutting it into 4 equal lengths and putting them in parallel, wind
36 turns. The wire size you need is #4, which you can build-up from
smaller dia., say 4 x #10 lacquer insulated. Next get 4 diodes, say
min. 220 amps, 300 volts, plus 4 large heat sinks, say 4" x 8" each.
Ideally the diodes come in pairs of positive stud and negative studs;
makes mounting and wiring much easier. All this will get you a good
DC welder, a start.
The big attraction of home-brew equipment utilizing antiquated
components is that you can fix it IF the magic smoke happens to
escape. No circuit boards at $ 300 each to replace. The most
expensive items were the 4 diodes at $ 35 CDN each. These were
replacements after we cooked the first (free) set! You may well ask
how in h**l do you manage to fry 220 amp diodes? REAL EASY if you are
not very careful installing the correct by-pass capacitors BEFORE you
apply the high frequency arc starter voltage to the welder. But that
is a later installment.
Meaning that the percentage of on time for each half of the wave was equal?
How was that hard to do? Wouldn't a simple R/C timer triggered from the
zero crossing do it?
Why would there be a hysteresis effect? Does the inductive load cause a
phase shift and move the zero crossing reference point?
Cool. How much does one that large cost roughly?
Your posts make me think building a welder might just be one hell of a fun
project. It seems like it's the type of project which you are almost
guaranteed to have to fry a few big parts before you figure out how to make
it all work right.
Let's just say that a commercial light dimmer type circuit doesn't cut
The uneven capacitor discharge for each half cycle has the effect of
introducing a DC pedestal onto the AC phase controlled current, which
transformers don't like and may, in the extreme, act as a short
circuit and blow the fuse / breaker.
On many phase controlled circuits to get the load to initially turn
on, the control resistance has to be turned lower than the desired
power level would indicate.....a reference scale on the pot shaft
would show this clearly.
While this may not matter for a light, fan, or even motor control, it
is very irritating for fine current control on a welder, where you
want the welding current to follow the pot adjustment - up or down -
immediately and very closely. Our circuit does all this very nicely
as verified by oscilloscope and actual usage.
The only draw-back is the limitation to 40 amps AC; this is the
largest triac available. Cost: About $10 or so. If you need higher
AC current symmetrical control there are methods of doing it with a
pair of inverse / parallel scr, but we didn't bother with this since
40amps AC is fine for our purposes.
I have some big SCRs with heat sinks and pulse transformers that I'd give
you if you get serious about building a current controller for a welder with
about 250 amps max output current.
I saved an article from EDN magazine by Narendra Paranjape where he shows
the circuit for a SCR current controller using a fan regulator. That info
is available via E-mail too
Sounds like you don't have a symmetry problem but I'll still note: an
alternistor (Teccor) might be a bettter choice than a triac in an
application like this. It behaves more like a pair of back-to-back
SCR's. They are available up to 40 amps. The trigger circuit must
(as you say) still provide symmetrical triggering, though.
Some AC motor controls use a full-wave bridge and a single large SCR.
They are mains-voltage AC in and mains-voltage AC out but the SCR
switches rectified DC. It's easy to get good symmetry in this sort of
Note that with AC tig (aluminum) some arc rectification can occur,
which may mean that the machine should be de-rated a bit for AC
operation to avoid saturation. It will tell you by buzzing loudly when
it's approaching a point of distress.
Jerry, there are also SCR controllers on the market that do all the
hard work. PCTI is one of the manufacturers. You just send simple
signals to the controller, like using a potentiometer or filtered PWM,
and it takes care of the rest. I use one by PCTI in my CyberTIG.
Thanks Jerry, but the odds of me getting serious and actually doing it are
very small. Most likely, if I did anything, I would create something small
that ran on 110 V with transformers too little to produce any real welding
power just to have fun playing with the idea and not with the intent of
building a welder I would actually want to use.
More fun to make one and probably cheaper, but wouldn't one
of these "Reactors" do the job? See:
I've looked into converting an AC buzz box to AC/DC too, but
the cost of the diodes always discourages me. I was curious
though if the above item would work for the reactor portion.
It looks like this one maybe wound on a ferro core. Hard to
tell a lot from the image. It would be interesting to
actually handle it and take measurements.
I put a big, high current, reactor in series with my Stick welder and made
it DC also. That combination makes Stick welding thin steel alot easier.
I can Stick weld at about 30 amps with my setup. I consider the series
reactor a good addition to any Stick welder that doesnt already have one.