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View Full Version : New to TIG, findings and questions



altaic
07-26-2009, 09:36 PM
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

DareBee
07-27-2009, 09:02 AM
Does any company make, for instance, 1/16" or 3/32" ID collets with the same OD as a 1/8" ID collet?

My Lincoln's all have the same outer body size, we only change the collet itself for tungsten sizes.

Are you using 2% thoriated (red) tungsten?
I have welded some pretty crappy material 1) If you take too long to make your puddle it will boil (porous fizziliy mess), use more amps.
2) Get GOOD quality filler into the puddle asap, this seems to displace the impurities and calm everything down. I find that using SS filler on the crappiest material works brilliantly.

altaic
07-27-2009, 12:43 PM
Awesome! I really appreciate the tips.

I'm using 2% ceriated tungsten, which seems to do okay with surface crud. Last time I was at the supply shop I picked up a pack of 2% thoriated to try, but I haven't had the chance yet... definitely will give it a go. I also mean to pick some 1.5% lanthanated next time as well, since Miller claims it's pretty similar to thoriated minus the radioactivity.

I tried stuffing some filler in there, with little success. First some ER70S6, which did very little, and the volcanic metal fouled my tungsten after a few seconds. I actually did try some SS filler, on recommendation from a forum post somewhere (might have been you, not sure), and there was an appreciable difference. I'm still grappling with the basics, though, so I'm certain I didn't make the most of it.

One idea I had was to cut a big chamfer on the joint seam and run a few ultra fast beads so there's barely fusion, and then make a slower pass so the pool and most of the heat is in the filler metal. I haven't tried it yet, though, and I have no idea if it'd work... The widest pool I could get without the fireworks show and the pin holes was seriously no larger than 1/16" and I had to move fast. It was more of a gesture than a weld.

diycnc
07-27-2009, 10:01 PM
i weld most steel with the stainless filler. i find it does a far better job at flowing with the weld bead. also on crappy dirty metal you can get a far nicer weld with the s/s filler. i am mostly welding old car parts that make it very hard to get 100% clean.

altaic
07-27-2009, 11:33 PM
i weld most steel with the stainless filler. i find it does a far better job at flowing with the weld bead. also on crappy dirty metal you can get a far nicer weld with the s/s filler. i am mostly welding old car parts that make it very hard to get 100% clean.

Cool. Do you guys recommend any particular type of SS filler? I think I have ER308L, although I could be misremembering.


My Lincoln's all have the same outer body size, we only change the collet itself for tungsten sizes.

What torch do you have? I've been googling without any luck... I'm not really sure what to search for... I tried "universal collet" which didn't turn any welding-related hits up, and "lincoln collet" turned up a bunch of standard collet/collet body combos. I did eventually find single-piece collets made by Weldcraft, but those replace the entire collet body each time you switch between tungsten.

Actually, I did discover that Weldcraft's monster "heavy duty" collet body, 11WP65, is specified for multiple heavy duty collets (1/16" to 1/4"). 'Course my torch is a WP20, which I'm pretty sure wouldn't work with that.

Thanks for the replies,
Will

DareBee
07-28-2009, 08:24 AM
Usually 308L

My mistake, my shop TIGs (Lincoln's) are using CK torches (we love the "flex" versions).
http://www.ckworldwide.com/ck20r.htm

altaic
07-28-2009, 01:22 PM
Hmm... CK has their special Wedge collets, but they appear to all require specific collet bodies also. Do you know what brand of collet you use?

DareBee
07-28-2009, 03:32 PM
Maybe I misunderstood this part of the topic? You are confusing me.
These collets are all the same OD (1/8, 3/32, 1/16, doesn't matter).
Anyway, I save a few bucks and use replacement collets by Prostar (Praxair brand).

altaic
07-28-2009, 04:11 PM
I think (hope) we're on the same page.

All of the collets I have (Weldcraft) have to be used in a specific collet body, i.e. 3/32" collet must be used with the 3/32" collet body, the 1/8" collet must be used with the 1/8" collet body, and so on. I didn't mic them, but I assume the ID of the collet body (and the OD of the collets) are different for each size.

Weldcraft's heavy duty collets all have the same OD and use the same collet body, as it seems yours do.

DareBee
07-29-2009, 08:56 AM
Weldcraft's heavy duty collets all have the same OD and use the same collet body, as it seems yours do

OK I am not confused anymore, that is correct by me.

altaic
07-29-2009, 11:19 PM
I measured the OD of my collets: the 1/8" collet has 0.175" OD, the 3/32" collet has 0.150" OD, and the 1/16" collet has 0.150" OD. The collet bodies have different hole diameters, though: the 1/8" collet body has 0.134" ø, the 3/32" collet body has 0.1" ø, and the 1/16" collet body has 0.07" ø. This is interesting, because the small collets can fit and still compress properly in the 1/8" collet body, since the OD of the collets are 0.150" and the hole is 0.134" in diameter. It's possible this may cause heating issues or something I don't know, but I think I'm going to give it a try.

Cheers,
Will

Rbeckett
07-07-2010, 05:03 PM
Altaic, the way it was explained to me was that the different collets are mated to the bodies to insure the maximum heat and current transfers are happening. If you have a poor fit in the handle you will generate heat and damage the handle part of the torch beyond just being able to replace the collet and body. I have not personally verified the accuracy of that statement, but it makes sense to me so I never questioned it. If the parts have close tolerance I usually replace them as a set to prevent damage to an expensive non replaceable part. Now you have me wondering too!!!!

snoeproe
08-30-2010, 08:31 PM
Yes, you need to match the collett size to the tungsten size, they must match.
I'm also wondering why you would want to tig weld mild carbon steel with stainless steel filler rod? Yes, it will work but stainless steel filler tig rods are far more expensive than mild steel filler rod. 70s-2 filler is great for out of position work with a sluggish puddle, where 70s-6 has a more fluid puddle and excelent wetting action. Both fillers are very easy to work with and cost much less than stainless steel filler..