Tool Time: TIG Welder Tech and the HTP Invertig 201
Posted at 10:41 AM / November 24, 2009
Tool Time: TIG Welder Tech and the HTP Invertig 201
With Project BubbaZ, I've been looking at the need to modify a twin turbo system that was originally designed for the GTO to fit my 1979 Z28. All of the cold side piping will need modification - and that is all .050" wall stainless tubing. The aluminum intercooler was also damaged in the accident - the drivers' side inlet to the intercooler was cracked and a bit of it was broken off. In order to accomodate both repair and modification of the turbo kit, I will need to weld it back together. I have a Millermatic 252, but that, to me, did not seem like the best "solution" - aluminum, thin stainless? Naah, this calls for a TIG welder.
Once I started shopping for a welder - and knew that I wanted an AC/DC machine to cover steel and aluminum - I needed to figure out exactly what kind of TIG welder would suit my needs. I searched multiple welding forums on the Internet. I watched Craigslist daily for about 6 weeks. During this time, I decided that I wanted an inverter style welding machine (smaller and lighter than a transformer-style welding machine). And in order to perform my minimum specification of 1/4" aluminum, I needed a 200 Amp (or higher) class of welding machine.
Why an inverter? Inverter welders perform "tricks" that transformer based welders cannot. Transformer based welders rely directly on the current that's coming out of your wall. This A/C signal is cycling at 60 Hz (here in the US; overseas, it's 50 Hz). So when you're welding aluminum in A/C mode, transformer based welders are only capable of cycling the output at line frequency. Inverter based welders, because of the way they're designed, allow you to have a wide range of frequency output adjustment - from 20 Hz on the low end, to 200Hz or higher on the high end. What difference does this make? This affects the width of the beam that the TIG torch is producing. Lower frequency means a wider bead; higher frequency is a narrower bead. The narrower the bead, the more heat can be concentrated in to a smaller area - so the puddle will form faster, and the Heat Affected Zone will be narrower.
The more advanced welders will have what's known as "AC Balance". This adjusts the dwell time spent on the positive side of the A/C pulse, versus the negative side of the A/C pulse. This Waveform Adjustment is highly desirable for aluminum welding; aluminum forms an oxide on its surface, which has a much higher melting point than aluminum by itself. The "positive" side of the pulse performs an oxide-removing cleaning action at the expense of heating the TIG tungsten tip; the "negative" side of the pulse transfers heat in to the work. Combine these together, and you can get a wave that cleans the oxide off - without overheating the tungsten - while transferring sufficient heat to the work for the welding process. Some transformer based welders (such as the Syncrowave) are capable of this adjustment, while most inverter welders are designed with this in mind as well.
I looked at numerous inverter welders... the Thermal Arc 185, the Miller Dynasty 200DX, the ESAB 161, and the HTP Invertig 201 were all on my "short list". Two things sold me on the HTP Invertig 201: the price was at a good cost vs. features point, and HTP President Jeff Noland was always ready to answer any question I had. I know that I could email him, right now, and have an answer within a couple of hours. He seems to always be "around".
I received my welder within a few days of ordering from HTP. I had it shipped to my work - so it was strapped to a pallet, shipped at a very reasonable cost via truck, and arrived with zero dents on the box. Perfect shape.
All together, I ordered the optional water cooled setup, a load of filler rod and tungstens, and a Pyrex gas lens cup kit from HTP. HTP has some of the best prices on the internet for filler and tungstens. The only things that were missing were a plug for the wall (which due to varying customer electrical requirements, they do not include), and a bottle of gas. At first I was wondering if the add-on water cooling setup was "worth the extra cost", but after welding with it, I give it two enthusiastic thumbs up.
HTP has a video on Tig welding that explains the features of their Invertig 201. After watching it a couple of times, I was able to get some decent beads laid down on some aluminum plate. Granted, I still need work on bead width consistency and reading the puddle as the material heats up, but this isn't bad for the first time ever welding aluminum. Prior to purchasing this welder, I'd never picked up a Tig torch. Ever.
For my first 'build project', I decided to build a welder / plasma cutter cart. I purchased 2"x2" square tube 1/8" wall, some 3/16" flat plate 'leftovers', a little 2"x2" angle iron, and some thin 1" stainless square. I cranked up the bandsaw and got busy with the Tig welder. This was a great learning experience for me - doing butt welds, T-welds, and a number of "uncomfortable position" welds. I tried to do all welds in the flat position, but not all were done on the bench. Some were done while kneeling (holding filler rod in one hand, the Tig torch in the other, one foot on the control pedal, and putting most of your weight on one knee). It was definitely a learning experience for me. But the more I welded, the better I got with it. It was very enjoyable. Gave me a new appreciation for guys that Tig weld roll cages in to cars. Out of position welding is much harder than it sounds!
In summary, HTP made the whole process easy. From the pre-sales questions, to having a 70+ minute DVD that shows the features of the Invertig, to after-sales tech support, they have been good to work with. I look forward to years of using my new Tig welder.
http://www.usaweld.com - HTP Welding Machines and Supplies
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Main photo (aluminum welding) credit and copyright is from HTP Weld.
