Newbie now with TIG.

[Hood]

Need to work a bit on the crater filling, sometimes I manage others I don't, easy enough to rectify but better if it is not there.

 

[Richard.]

Need to work a bit on the crater filling, sometimes I manage others I don't, easy enough to rectify but better if it is not there.

Back step it while phasing down.
Perfect every time.

 

[Hood]

@dazza sorry to hijack your thread but just wanted to post this info here as it is relating to my post from a few days ago.

I did a couple of short test runs as I was wondering if the AC Frequency was maybe why I seem to be much lower current than others. So anyway here it is, one is done at 140 amps and 70Hz the other 180 amps and 110Hz

I seem to prefer the lower Hz, maybe because I have been used to machines that didn't have variable frequency so would have been 50Hz I presume.

 

[Richard.]

For a fillet joint like that I'd be up 120-150 hz.
At lower hz the focus tends to be wider and less concentration into the joint corner. It's not essential because you can achieve similar by tungsten prep but I am a big fan of frequency adjustment. Such a great setting for easily tailoring arc width to joint type.

 

[Hood]

The most my welder will do at 180amps is 110Hz, goes as high as 200 at lower amperages.
For me the 140amps and 75Hz seemed to be the best, the one on the right just didn't feel right and, to my eyes at least, doesn't look right.
As said probably just what I am used to.

 

[Richard.]

The most my welder will do at 180amps is 110Hz, goes as high as 200 at lower amperages.
For me the 140amps and 75Hz seemed to be the best, the one on the right just didn't feel right and, to my eyes at least, doesn't look right.
As said probably just what I am used to.

So long as you keep the arc and pool right in the corner you can do it however. There is no written rule on it.
It's very easy in a fillet joint with Alu to produce the joint between the two plates and all looks well but fusion or lack of it right in the corner makes that joint pretty much useless. Frequency set up to the joint is a good way of preventing such defects. It's not the only way but it's probably the best way imo if the unit has the feature. It's weird yours limits the hz on current.
Not that it's an issue as higher current joints don't tend to require the arc focus as a lower current joint

 

[Brad93]

It is mad the difference a higher frequency, even just 40-60hz more can make on a fillet joint. The better the pool flows into the corner the quicker you can progress down the joint and ultimately the neater it comes out in my experience.

 

[Hood]

It is mad the difference a higher frequency, even just 40-60hz more can make on a fillet joint. The better the pool flows into the corner the quicker you can progress down the joint and ultimately the neater it comes out in my experience.

I found the opposite even with a 40 amp increase. It may well be down to my technique but it definitely was slower welding the first run (right side of pic, 180A 110Hz) then the second run (Left side 140A 70Hz) and it was definitely not because the Alu was warmed after the first run as I let it sit in the vice for over 1/2 hr between welds.
Will do some more experimenting when I get a chance, did a couple with messing about with the frequency and also using pulsing and some seemed nice but it was hard to tell the differences as when I was doing that it was one after the other so the heat was in the metal, will have to chop up a load of bits and tack them then try different settings all on cold metal.

 

[Hood]

Oh one thing I did notice, the higher frequency tended to have less of a crater, in the pic above I never attempted to fill the crater in either.

 

[Richard.]

Welding speed WILL be faster with a more concentrated arc. Pen will be deeper and narrower too these are facts not opinions.
If your arc width is wider your pool is wider and your time spent in one place should be longer to achieve fusion and reinforce with filler over the bigger area
It won't be much because you will hopefully be doing things another way to keep things tight in the corner.
If your going slower by increasing only frequency then that suggests to me your doing it unneeded because the setting certainly isn't making you go slower.

 

[Richard.]

Assuming you did the first run at the higher frequency/current when the plate was cold and the second at the lower settings while it was heat soaked then yes that make sense but your lower settings were not making you go faster the plate heat was. If that's not the case and both performed cold then that doesn't make sense to me.

 

[Hood]

Assuming you did the first run at the higher frequency/current when the plate was cold and the second at the lower settings while it was heat soaked then yes that make sense but your lower settings were not making you go faster the plate heat was. If that's not the case and both performed cold then that doesn't make sense to me.

As said I let the plate cool before the second run.
Will maybe get a chance over the weekend to do some more testing, will see how it goes.

 

[hotrodder]

Lincoln invertecs (so presumably some Selco kit too?) limit AC frequency at higher amperages too. Forget the actual numbers but my v205 is more limited in triangular wave than it is in squarewave

While higher AC frequencies tighten/stiffen the arc they do not increase penetration*. Lower AC frequencies are way better at heating the work (and the tungsten) everything else being equal. Obviously everything is related to everything else settings wise so everything else isn't usual left equal... if for whatever reason you want to bias the AC frequency as far towards EN as the work will tolerate then the amount of EN varies with AC frequency and a few weld beads will demonstrate that as you turn the frequency up you typically need to turn the %EN down to keep the weldpool clean and fluid. Along the same lines grab a couple of chunks (so they're all cold initially) of thick ally and see how long it takes to get a weldpool going at different AC frequencies when the amperage is a bit on the low side

Personally i think that high AC frequencies are often a bit over rated for manual work. Especially the common one of 'higher frequencies for fillets' because while the arc is constricted and stiffer it'll also dance about a lot more given the chance, say the initial tacks for example.
Obviously lots of ways to skin a cat but my take is that higher AC frequencies are more useful for thinner materials much like triangular waveforms are... a fillet weld on 6+ mm stuff doesn't need a constricted arc and being able to deposit a small narrow weld on such a joint is kinda pointless too most of the time. A fillet on 1mm ally (without any burn through or LOF!) on the other hand is not an easy weld to make but most people would find it more difficult on an old sinewave beast than with an inverter at over 100Hz. Similar deal with outside corners... if the weld's gonna be linished out for a crisp edge then higher frequencies make life easier, especially if the part is thin sheet ally

* As with a high frequency DC pulse the constricted arc increases the depth to width relationship of the weldpool not the penetration... maybe a bit pedantic, definately subtle but not the same as simply increasing penetration

 

[Richard.]

Lincoln invertecs (so presumably some Selco kit too?) limit AC frequency at higher amperages too. Forget the actual numbers but my v205 is more limited in triangular wave than it is in squarewave

While higher AC frequencies tighten/stiffen the arc they do not increase penetration*. Lower AC frequencies are way better at heating the work (and the tungsten) everything else being equal. Obviously everything is related to everything else settings wise so everything else isn't usual left equal... if for whatever reason you want to bias the AC frequency as far towards EN as the work will tolerate then the amount of EN varies with AC frequency and a few weld beads will demonstrate that as you turn the frequency up you typically need to turn the %EN down to keep the weldpool clean and fluid. Along the same lines grab a couple of chunks (so they're all cold initially) of thick ally and see how long it takes to get a weldpool going at different AC frequencies when the amperage is a bit on the low side

Personally i think that high AC frequencies are often a bit over rated for manual work. Especially the common one of 'higher frequencies for fillets' because while the arc is constricted and stiffer it'll also dance about a lot more given the chance, say the initial tacks for example.
Obviously lots of ways to skin a cat but my take is that higher AC frequencies are more useful for thinner materials much like triangular waveforms are... a fillet weld on 6+ mm stuff doesn't need a constricted arc and being able to deposit a small narrow weld on such a joint is kinda pointless too most of the time. A fillet on 1mm ally (without any burn through or LOF!) on the other hand is not an easy weld to make but most people would find it more difficult on an old sinewave beast than with an inverter at over 100Hz. Similar deal with outside corners... if the weld's gonna be linished out for a crisp edge then higher frequencies make life easier, especially if the part is thin sheet ally

* As with a high frequency DC pulse the constricted arc increases the depth to width relationship of the weldpool not the penetration... maybe a bit pedantic, definately subtle but not the same as simply increasing penetration

Unusually but I don't agree with a chunk of this.
Penetration is as I said in my post narrower and deeper with high frequency and it's wider and not as deep with lower hz frequency.
The volume of metal penetrating the surface is probably the same with all other settings been equal but higher hz the actual depth of pen goes further and narrower.
I also would say the arc dances around more on an inside corner at lower frequency. It tends to try and favour a side and by constricting the arc I can get a pool going right in the corner where I want it rather than up the side wall. While I agree heavy section doesn't want loads of hz throwing at it as a suitable fillet size needs achieving with a bit of arc width but from my experience frequency setting is a very useful setting when used correctly and tailored to the work. Avoiding close through holes, thin gage butt joints, thin to medium gage fillets and many more situations where the feature makes life a little more of a luxury.
I've done plenty of time with fixed hz transformers and they certainly show that freq isn't essential but I think it's a lot more useful than you say.

 

[hotrodder]

Like i said grab a couple of chunks of thick ally and see how long it takes to get a weld pool at different frequencies. Lower AC frequencies do a better job of heating the part (and/or the tungsten).
For a given weld width higher frequencies are gonna produce a deeper weldpool but they don't increase penetration, they increase the depth to width ratio which is subtly different...
Several jobs i do (fillets on thick stuff) where i could really do with either more than 200A or an Ar-He mix but turning the AC frequency down makes them doable. At higher frequencies (despite the 'improved' arc focus) i get two weldpools, one either side of the root. If higher AC frequencies 'increased depth of penetration' the opposite would happen

 

[dazza]

As the welder was setup thought i would have another go at some aluminium. Still rubbish .

 

[Hood]

Practice makes perfect

 

[dazza]

Practice makes perfect

Think i'm just going to give up on the aluminium, i can sort of stick other things together with it. Maybe one day i will try a different machine then i will know 100% that its me being rubbish rather than the settings or the machine.

 

[Hood]

I find Alu the easiest to Tig but others find it the hardest, not sure why, maybe just that the first thing I ever tig welded was Alu

 

[dazza]

I'm going to try changing the cup i only have 2, i was messing about with the ac balance today and did not notice the cleaning area changing.