What criteria ? Gas Lens

[Bruce]

I have 3 gas lens' that came with the torch. (roughly 5mm / 8mm /12mm)

Along with this came 3 torch collets for 1.8, 2.4 and 3.2 (?) roughly and I made the presumption that the 5mm lens for 1.8 etc etc. However I found that using the 12 mm lens on the 2.4 gives me a far superior bead. Indeed, so to on the 1.8. So I think my presumption was wrong. So how then does one set the criteria for lens size choice?

 

[shenion]

I use the Miller Calculator.

But that sets the minimum size needed. I guess as small as possible to fit in tight places. A big cup on an inside corner might make it hard to see or get the filler under. Going bigger would just make the flow even smoother.

I just have one lens, I think it is 8mm. Have it set up, but have not tried it yet.

 

[fingers99]

Just as he says.

What you have are unlikely to be gas lenses, more likely plain ceramics. Gas lenses have a diffuser (usually looks like a sort of fine mesh grill) between the ceramic and the collet which gives better gas flow so you can extend the electrode further and/or use a narrower ceramic for better access to those tight places.

Weldequip does them. (for example)

 

[Bruce]

Ta thanks guys. And you are correct, they are just ceramics. (that'll teach me to just look at the piccies on the tintinet and not read the gloss)

One last question then if I may. Should I be adjusting gasflow for different diameters? I just have my valve set for 10lt/min and lay waste as best I can.

 

[fingers99]

With most stuff you'll set the gas flow more to look after the tungsten than the base metal, so what you need is going to be determined by amperage and how big the tungsten is. 10lt/min should be safe for just about anything.

Somewhere, I think, Miller publish some guidelines.

 

[snowcat]

With most stuff you'll set the gas flow more to look after the tungsten than the base metal, so what you need is going to be determined by amperage and how big the tungsten is. 10lt/min should be safe for just about anything.

Somewhere, I think, Miller publish some guidelines.

emmm cant agree there, gas flows on TIG should be chosen for material, ceramic and weld, a gas lens is about improving coverage to the workpiece and preventing non covered areas within the work, too much gas especially on S/S where you will notice it will create areas that are insufficiently covered... If it was simply about protecting the tungsten procedures such as purging would not be needed..

 

[fingers99]

I never said that the gas flow was simply about protecting the tungsten! If it were, I don't think we'd be TIG welding. (Not sure what we would be doing.)

But purging is something you won't normally be doing unless you're welding stainless or titanium.

Generally, if the electrode stays clean, the base metal will be OK. If the electrode doesn't, you're in trouble.

 

[snowcat]

I never said that the gas flow was simply about protecting the tungsten! If it were, I don't think we'd be TIG welding. (Not sure what we would be doing.)

But purging is something you won't normally be doing unless you're welding stainless or titanium.

Generally, if the electrode stays clean, the base metal will be OK. If the electrode doesn't, you're in trouble.

M/S pipe open root?

 

[fingers99]

M/S pipe open root?

And that's likely to be "normal" for Bruce?

 

[snowcat]

And that's likely to be "normal" for Bruce?

But Bruce's original question was on the criteria of a gas lens? simple answer is to provide better coverage to the work peice....

over wise don't worry set a constant flow rate, one ceramic, tung, and have done with it...

I'm not saying running open root pipes is the norm for Bruce, BUT how can you recommend gas flows, choices on ceramics, WITHOUT knowing what Bruce is trying to weld????? How can you blanket recommend 10LPM without knowing any other parameters??? not even material.

 

[fingers99]

I wasn't. "10 l/pm should be safe enough for just about anything" is supposed to intimate that it'll be too much for a lot of stuff.

One thing I know for sure, he hasn't got gas lenses! And, God bless him, he's only starting out.

Now, pace, enough.

I look forward to the tutorial on open root TIG on M/S pipes. I doubt if it's anything Bruce or I will be doing in the near future (or perhaps in this lifetime), but it would be a really great read!

 

[Drains]

Fingers, you make me laugh.

Bruce, what you need is this Tig Welding Calculator.
You too fingers


note, to convert cfh to lpm, x by .472.

So halve it, ish.

11 cfh (as used on 3mm m/s fillet weld), will be around 6 lpm. Too much above that and you'll get turbulence. 10lpm would be a 'mare.

 

[Weldingartisan]

Those calculators are all very well if you have every combination of tungsten and ceramic, which I dare say most haven't. I would also like to see the average TIG hand weld a 16swg ally butt weld at 75amps! It's not often I change my gas from 8 l/m. W/A

 

[Bruce]

Bit gusty this weekend wasn't it!

OK, so on the balance of the reponses here I made some changes to my set up this weekend for a project that has been on the back burner for a while.

It's my favourite Lazee-Boy reclining chair see. The one I plonk my butt in to watch the idiot box. I love this chair. The brats know better than to try and sit in it, and it drives the Boss crazy because it's so old and tatty and doesn't colour co-ordinate with the rest of the lounge suite. But I love it, like a tea pot it takes years of dedication to break in your arm chair until it is just right. Well she thought all her Xmasses had come at once when the metal reclining doo-daas in the frame broke, and I could see her devious mind planning a trip on Saturday to DFS to find a suitable replacement. Modern reclining couches are ****e, it'd be more comfortable to sit on a breeze block so I whipped it out to the shed to see if I could make a repair.

Well, after a feasability study in which the sulking wench tried to poison my coffee with vinegar, I realised removing the leather was too much like hard work and so a bit of close work with the Wenzhou Mao Electric Company 160 Amp Tig/MMA/ Plasma cutter was called for. All you stick welders can only weep here....no spatter with tig :smugbastid smilie:

Well as some of you may know my welding table is a second class citizen to the Boss's rubbish, and so has the unenvious position next to the garage door.
Not a particularly good place to try your hand when the wind is gusting 40mph. But a judiciously placed bucket of water in case things went horribly wrong, a number 4 ceramic cup with 1.8 tungsten and 8lpm flow I set about ruining the Boss's day.

Well let me tell you Miller knows sweet FA about British weather and the tribulations of Fred and his shed, because as I chased the weld bead admiring my work, behind the ceramic cup bloody great craters were suddenly errupting like the volcanic acne on a scroats face when the Bizzies have them in a headlock.

Maybe more gas, bigger cup and less heat? A bit like 10 years into a marriage then, and I still had a lava field behind me.

It was only when I put the chair on top of a cardboard box mountain of the Boss's old dresses which she has been hoarding for the last 10 years promising me that one day she will again fit into them, and I could close the garage door behind me, that I could eventually sign my name to that weld bead. It did occur to me tho as I was tigging away, that right about then a stick welder might actually come in handy, especially an AC one

Anyway, my question is. If you are outside and the wind is up, is it possible to tig at all? i.e. would a gas lense help?
Are there any other goodies a Fred should get to augment his collection with?

 

[fingers99]

But -- important bit -- you did get your chair back?

Of course, wind aside, the other reason for craters can be a dirty electrode.

Outside in the wind, any of the processes which use a gas shield are likely to run into problems: you have to try and keep the wind out somehow. On thicker stuff (say 1.5mm and up), gasless MIG is good in these conditions (curse it). Otherwise oxy/acetylene or arc.

 

[Dangle_kt]

what a great read bruce! I enjoyed that - more stories please!

 

[Bruce]

But -- important bit -- you did get your chair back?

"did I get my chair back" .... ?!

...and on Sunday I was rewarded with peace and quiet as I gloated...except for the occaisional kitchen cupboard door slam. Even the kids hid in their bedroom with the Wii.