TIG Welding: The First Day (by alaric)
Today, I took the day off work to take my new TIG welder for a spin.
I started by getting some pure argon shielding gas; prices for this stuff vary widely (10 litres full of gas at 200 bar for £35 plus £15 shipping, or the same for £77.90 including shipping?), but I managed to get a 9 litre cylinder filled for £25 at Target Tools and Supplies in Gloucester. They don't seem to have a web site, but they're here.
With that installed, everything worked fine:
I didn't have to find out how wonderful R-Tech's customer service are, because the thing arrived in full working order and was easy to set up and use 🙂 I ran a few test beads across some scrap steel, and it worked pretty much as I remembered from my TIG course all those years ago, so I set to doing something useful.
First job was to fix up the dodgy welds holding the new steering gear onto the welding trolley. I ground down the two lumpy lines of poor stick welding on either side of the join I actually wanted to weld together (it had bridged in a couple of spots, which was holding it together, but it was far from ideal), and set to it with the TIG. The result was hardly beautiful, as I didn't weld it completely flat so it was a bit irregular to start with, but with no fuss at all I was able to make it bridge the gap. I'm finding TIG much easier to control than stick - I can see what I'm doing far better, so I know where I'm welding, and because it's not constantly depositing metal, if the weld pool hasn't formed where I want it to, I can move it and make sure both sides are melting together before I start putting in filler! As I was welding a 3mm thick flat bar to a 2mm-wall 25mm square tube, getting both sides to melt together wasn't an obvious operation of just applying heat to the middle, so being able to manipulate the arc was a great bonus here.
Next, I cut off some 10mm square tube to weld onto the chassis so as to stop the steering arm from swinging too far from side to side. Originally, it was possible to steer too far, causing one of the front wheels to jam underneath the front of the main body of the trolley, which is no fun; these two stops put a stop to that! However, this was my first experience of welding something that's not horizontal and easily accessible. It was a real squeeze getting to the place they had to be welded, so I kept finding my torch hand or the hand feeding the wire in snagging on things. When attaching one of the stops, I lost track of where the filler wire was while welding; it had caught on something and was being pushed aside of where I was pointing it, outside the area I could see. While I faffed with this, I left the torch pointing at one place for too long and melted the end of one of the stops off! It wasn't a bit that does anything, so I'll probably grind it off and do the same on the other one to make them match again, but still, it wasn't great...
Also, when welding in awkward positions, I couldn't see the arc so well and kept poking the tungsten electrode into the weld pool. This meant re-grinding it, which wasn't ideal as it contains traces of thorium (a radioisotope), and you don't want too much thorium dust getting into your lungs. I decided to practice a bit with the torch in awkward positions on a bit of scrap, and got the tungsten stuck again, and decided not to re-grind it - I nipped out to a nearby welding supply shop and picked up some E3 tungstens, which aren't radioactive. With one of those ground and installed, I set to a little project: making myself a monitor stand for the office (my monitor currently sits on a stack of books).
I started with flat welds to put the top together, which went fine:
Then welded some tubes onto the bottom to make legs:
This was a lot harder. I've not got the correct angle and electrode stick-out yet, so was struggling to see the weld pool, and ended up dipping the tungsten in the metal a lot. Also, heat rises, so I was having to work to get the flat bit I was welding to to melt and form a pool, while the tube sticking up from it was happy to melt and then flop down, making a nice arch. I think I can fix this with better torch positioning - I need to experiment more!
As well as working on my torch holding, I think I also need to pick up some thicker filler rod - I've got a kilogram of 1mm mild steel rod, and 1mm rod seems to just disappear; I struggled to feed it in fast enough and it kept balling up. I think I had the right amperage for the metal (I was using 70 amps on 3mm thick steel with a 1.6mm tungsten), given the penetration and the rate at which the weld pool formed, so I think my rod's just too thin.
Also, I need to figure out which sized ceramic to use. I set the torch up with the smallest one (which has "5" printed on the side; I have a "6" and a "7" as well), assuming that it's best to start small and move up, but during the post-flow stage I'm seeing the surface of the weld pool rippling quite violently, and when it solidifies, it has a correspondingly ripply surface texture. I'm running the gas regulator at 8 litres/minute, an I've been recommended to go from 8 to 12 for most jobs, so I don't think the gas flow rate is too high; I suspect that the narrow ceramic is forcing the gas into a tight stream so it runs faster and blows the weld pool around.
Now, when we got a compressor, we decided to name it Compressita Wurst in recognition of the recent Eurovision Song Contest winner. Continuing this tradition, the TIG welder is, of course, called Tigger, meaning that my old stick welder is therefore now called Pooh. If I get a plasma cutter, I'll call it Piglet.
I'm delighted with my welder, and look forward to improving my technique! I've a few new projects in mind - fixing up our barbeques with new legs, welding stainless steel grilles for them, and making myself a better welding bench (I can shorten the legs on my current one and make it into a shelf underneath the new one); but my most urgent project is going to be finishing off the new server chassis!
My only complaint with the R-Tech TIG161 welder is that the power switch is all the way around at the back; to turn it on and off, I have to crouch down to reach under the shelf to the back of the thing. Do other people have a handy switch on the socket it plugs into? Or do they not shove it on a shelf? I don't know.
Ok, one other complaint. The hose that connects the gas regulator to the welder (that looks white in the picture of my welding setup), when it arrived, smelt disgusting. It actually smelt like excrement. Not precisely like excrement - it was clearly the smell of some volatiles outgassing out of new synthetic materials - but that's the closest smell that came to mind. At least this was only apparent when I had my face near it while fiddling with the hose fittings to connect it up, and the smell has subsided after a day's usage. Thank God. That's the smelliest pipe I've ever encountered.
Alaric, Metalworking | alaric | 
Wed 22nd Jul 2015 11:19 pm
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By John Cowan, Thu 23rd Jul 2015 @ 12:53 pm
Yeesh, 70A at 240V? Do people on your side of the pond routinely have circuits like that lying about, or did you have it installed specially to run the welder? Our houses receive 240V, but most normal equipment (excluding electric stoves, washing machines, water heaters, etc) run at 120V using one hot wire and a neutral wire from a center tap on the house's transformer. Typical individual circuits are 15-30A at 120V, depending on how old the house is.