Hi all, I just bought a nice Miller Dynasty 200 DX and I'm happily making slow but sure progress with my TIG skills.
Thoughts:
My first day of welding was mediocre (hopefully other newbies may find this helpful): The second piece of mild steel I practiced on completely threw me off. I prepped the base metal by cleaning it with acetone, grounding it, and cleaning it again, as I had done with my first piece and all the pieces since. However, I couldn't get a good molten pool for the life of me, let alone lay a bead; it was like lava rock, a porous mess. I checked everything, tried reducing heat, reground my tungsten, tried other types of tungsten, etc., to no avail.
The next day it occurred to me to try running a bead on my first piece of metal I practiced on. It was great! So, I tried the second piece again and it was the some old mess. Moral of the story: Sometimes your base metal is crap (especially if you picked it up the so-called "weld metal" at Home Depot).
I have actually found that contaminated tungsten with good base metal produces nowhere near the mess of bad base metal. Of course, I spend quite a lot of time grinding my tungsten sparkly clean with a dedicated grinding wheel.
Possible causes I have read about include: improperly set gas flow (too little won't provide coverage, and too much will create turbulence and draw in air; I use 15-20 CFH), blocked gas flow (a reversed collet among other things can do this), a bad bottle of argon (rare, but possible), contaminated tungsten, and finally contaminated base metal (surface crud, or as in my case the metal itself).
Question:
Anyhow, I have a quick question unrelated to technique and such-- I couldn't help but notice that every collet size has a dedicated collet body. Why is this? With machining, usually there is a single large collet body that fits a variety of collet sizes. Does any company make, for instance, 1/16" or 3/32" ID collets with the same OD as a 1/8" ID collet?
The reason this bugs me a bit is that I'm thinking about getting a CK Worldwide Gas Saver kit with pyrex cups, which would require changing out the screen/adaptor when switching collet sizes. It'd be nice if I could just stock the 1/8" screen/adaptor spares and a variety of collets as opposed to having to stock screen/adaptors of every size.
Cheers,
Will