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Thread: Why can't I add a spool gun to my TIG?

  1. #1

    Default Why can't I add a spool gun to my TIG?

    We typically have a question every month or so exactly like this. The reason has a very technical answer, but I will try to put it in laymen terms as best as possible.

    There is a "bargain basement" company that claims its a cinch to add a spool gun to their TIG because the fittings match up. Maybe they can, who knows? But I doubt it.

    Here's why:

    There are generally two types of power sources: Constant Current (CC) and Constant Voltage (CV). Constant Current is required for TIG and STICK processes. The current remains fairly constant but the voltage varies because the actual voltage is controlled by the arc length. As the arc gets shorter, the volts drop and the arc tends to go out and even stick (if it gets too close to the base metal) because there is not enough total wattage to sustain a welding arc.

    The Constant Voltage machine is typically your MIG or Flux core processes. The voltage remains at a steady level as the arc is constantly shorted to the workpiece and the metal is transferred. The current varies with the length of stickout of the wire. One reason you'll seldom see a current reading on a stand alone mig is that the wire speed IS the amperage. Though its not an amp equivalent, the speed with which the wire is fed determines actual amperage output.

    Now there are subset terms within the CC and CV categories such as droopers and constant potential that describe nuances of these two basic categories. But I won't discuss that here...some even gets beyond my reach. However, there are a couple of things that will allow a wire feed unit to run on Constant Current. The wire feeder must be able to sense the voltage and compensate the wire speed for the increase or decrease in voltage. Many "suitcase" wire feeders that portable welding guys carry are this kind of wire feeder. However, most users tend to agree that the voltage sensing wire feed system is not ideal. It is a "get by" approach to welding MIG when nothing else is available as a power source. A lot of older "pipeline" welders were only able to provide CC voltage and thus the need for voltage sensing wire feeders as wire feed units became popular on the job site. Modern units now have taps that allow CV operation. But I digress...

    Getting back to why a spool gun won't work on a typical TIG/STICK unit is that spool guns (at least the ones most people provide) are not voltage sensing and operate with a steady wire feed control. What typically happens if a spool gun is operated in CC is that the wire feed will appear to be very erratic, while its actually the arc is not being controlled and frequent burn back and start stopping occur with very little usable welding happening between.

    Now the thing about inverters is that an inverter can be made to produce both CC and CV current relatively easily. The problem is that most tigs are not produced with both CC and CV capability, especially with the cheapest importers.

    Our smallest I-MIG products, the I-MIG 160-200-205 are both CC and CV capable. They can be used for stick or scratch start tig (in a pinch). These inverters are very good at both MIG and STICK...one reason our price is not as cheap as some of the other "import" brands like HF which produce low duty cycle transformer machines. An advantage that the I MIGS have is that they have Arc Force control. The arc force control in MIG is also known as Slope or inductance (another whole lesson). Suffice it to say, that arc force's practical application is that it controls the welding arc qualities. It can make the unit with a soft buttery arc with a very liquid puddle, or a stiff, harsh arc that is very tight and defined with very little lateral wet in of the puddle. There is nothing wrong with either extreme, as each has its own applications. In stick mode, the arc force helps to boost amps as the arc is held short to keep the arc stable and the puddle hot.

    Now back to the question if a MIG can have CC/CV then why not TIG? Well, space consideration is one. With advanced tig features, there is very little room left for a dedicated CV circuit. Also, tig is considered the preferred way of welding aluminum or any metal for that matter. This makes a spool gun as unnecessary as mammary glands on a male porcine animal. I have looked at these so called "spool gun" capable tigs and have seen nothing to indicate that they have a special CV setting. Just because a spool gun will hook up to a tig unit, does not mean that it should hook up to it.

    Sure it is possible...but not probable to have a TIG/Spool gun combination. Spool guns are extremely expensive to operate, with lower quality welds than a tig. So why would someone jeopardize their weld quality by using a spool gun when a much better option is at their finger tips? Again, adding a spool gun is possible with the right technology, but does it really make that much sense?
    Last edited by performance; 05-08-2010 at 01:35 AM.

  2. Default

    Thank you, I always had the question in the back of my head as to why the Miller mig welder at work reads in voltage, but TIG welders read in amps. Never really cared that much, but not that I read the explanation, it makes sense.
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  3. #3
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    Default

    Could not have put it better myself.

    Having worked on welding and cutting equipment for many years. I have always wondered if there wasn’t some way to make the two processes compatible but it would take another whole set of dedicated circuits and control boards. And a multi process machine is a crowded piece of real estate. But who knows smarter people than me come up with some of the dammedest things everyday.

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  4. #4

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    Hello,

    My last post didnt go through for some reason. Sorry if this double posts. I was just gonna say doesnt a robotic tig welder basicly have a spool gun. It is just acting like as a filler instead of the electrode. If they did come up with one it would have to have a good throttle control on it. Perhaps even a ratcheting action. A oversized mechanical pencil would be a better idea. With the rod sticking out the backend. Be a lot easier with those welding gloves on. Hey, thats a good idea. Dont steel it, I came up with it first.

    Thanks
    Frank

    I have a 250 EX welder and several other machines and equipment to allow for small scale manufacturing and prototyping of inventions

    I am located in Oregon about 20 minutes west of Portland

  5. #5
    Join Date
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    The short answer provided by Mark is partly correct. In reality, we have Tip Tig, which IS a wire fed tig process. This process is not new, it has been used in Europe for many years. It is available in a manual (semi automatic) version for non automated welding. The importer claims that it is easier to learn TipTig than it is to learn Tig. Since the filler wire is fed, the person only has to control his torch height and speed. The TipTig feeds the wire and agitates the puddle for better weldment.

    http://www.google.com/search?client=...UTF-8&oe=UTF-8
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  6. #6

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    A/C Guy,
    The answer I provided is not only partly correct, it is Completely correct...In fact it is not an answer at all. It is a statement.

    A spool gun is not a tip tig.
    The difference being is the wire does not serve as an electrode. A tip tig is an auto feeding tig, that advances the wire into the arc zone and eventually into the puddle.
    A spool gun feeds the wire into the puddle automatically too, but in reality, it short circuits (or sprays) into the weld. There is a big difference. The forces at play on the wire are much greater than just being melted by an outside arc. On a spool gun, it IS the arc, or at least the arc is transferred by the wire. The two processes couldn't be further apart.

  7. #7

    Default

    If your looking for a one handed operationCK makes a tig wire feeder,but it's only similar to a spool gun in that the feed is automated. It's much like the tip tig, but the wire is cold not hot. http://www.ckworldwide.com/coldwire.htm
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  8. #8

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    This is cool stuff to me. Ive long thought about a tig process that automatically feeds the wire. Ive seen that tig tip also. My realy thought about this was actually printing up parts. If you can put a welded micro dot down, you could easily fabricate any part from metal using a 3d welder. As an inventor this is something I dream about, lol. They probably already have this kinda stuff already. I just never heard of it. It would be so cool just to print out any part from a cad drawing. Without having to machine it. You could do some really complex inner work that you cant do with machining. Anyways, thanks you all for the posts.
    Frank

    I have a 250 EX welder and several other machines and equipment to allow for small scale manufacturing and prototyping of inventions

    I am located in Oregon about 20 minutes west of Portland

  9. #9

    Default

    Ive thought about in the past of using a wire feeder from a harbor frieght welder that doesnt work anymore but the feeder does and using it on a turn table to make and automatic feeder. Im sure it would work but I hvent got around to doing it
    Brandon Raineri
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  10. #10

    Default

    Quote Originally Posted by scootarida1 View Post
    Ive thought about in the past of using a wire feeder from a harbor frieght welder that doesnt work anymore but the feeder does and using it on a turn table to make and automatic feeder. Im sure it would work but I hvent got around to doing it
    or even adapt that idea as seen on the CK site. I might have to get around to making that and see if it works
    Brandon Raineri
    The Pennsylvania State University
    Studying Industrial Engineering

    Everlast PowerPro 205
    Everlast I-Mig 200
    SpeedGlas 9100x
    Milwaukee 14" Dry Cut Saw
    Craftsman 6"x48" Belt Sander with 9" Disc Sander

  11. #11

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    It would seem to me that if you used wire feeder for tig it would need to be a pulsed feeder. Using a constant feed may not allow the wire to melt fast enough and may cool the puddle. Penetration would not be there for a good weld joint.

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  12. #12

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    Yeah i was considering using something like a strobe light but I dont know if that would work or maybe even something like a relay for a car for a blinker mechanism
    Brandon Raineri
    The Pennsylvania State University
    Studying Industrial Engineering

    Everlast PowerPro 205
    Everlast I-Mig 200
    SpeedGlas 9100x
    Milwaukee 14" Dry Cut Saw
    Craftsman 6"x48" Belt Sander with 9" Disc Sander

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