help me..........

[DrNik]

hi to everyone on the forum, ive got me a migatronic PI200, well, came with no instructions, got so many controls, ive sent 2 rockets over kuwait and defribulated a dead pigeon back to life so far, but cant get welding aluminum to any kind of art, its 1.5mm chequerplate and i can lay a bead piece of cake on the flat , but when i come to lap weld the torch seems to want to strike to either plate but not to the intersection i have to make a puddle of crap and then it will weld a bit,it i want to know what amps/% cleaning action, and any other buttons/settings im trying to weld on a 90 degrees, and almost let the to edges join , so as the title says help me........ maybe if there is a member close enough i could ply them with tea and biscuits, maybe something stronger

 

[hotrodder]

but when i come to lap weld the torch seems to want to strike to either plate but not to the intersection

That's pretty much what ally is like when putting the initial tacks on a fillet or lap joint, especially if arc length is excessive. Long thread on the subject here... http://www.mig-welding.co.uk/forum/showthread.php?t=33791 and a generic demo of arc length here and in the TIG tutorial. Sneaking up on it with lowish amperage tends to make things worse. Calling out amperage settings ain't likely to end well... arc length makes a big difference as does travel speed and size of the work piece- small offcuts quickly get heat soaked lowering the amperage needed. Good rule of thumb for a starting point is 1A per thou (0.001") or 40A per mm... those of us that've been welding for years may weld ally at higher amps than that (higher travel speed) and use around double the amperage for tacking- hot, quick and the arc doesn't get a chance to dance about. If you're not quick and accurate the result is likely to be a big hole though.

Balance settings aren't a 'make or break' type of deal, more a trade off between a clean and shiney weld pool and giving the tungsten a hard time. Depending on the kit that typically means anywhere between 60 and 75% EN will be in the ball park. If the weldpool is dirty/sluggish or has 'bits' in it then (assuming the ally isn't manky/heavily oxidised) you need a little more EP, if the weldpool is clean but the tungsten is melting too much (huge ball on the end) then more EN. Note that different manufacturers do things differently i.e. with some kit turning the balance up = more EN, some do it the other way round and others have a dial marked from say -5 to +5 instead of 0 - 10. Easily worked out with a few beads on plate if the markings on the machine aren't clear

 

[Shox Dr]

Laps are one of the hardest to master. The two pieces need to be held tight to each other, any gap and the top sheet will want to disappear because of the higher ampage required to melt the bottom sheet.

So checker plate will not be easy, especially if this is all new to you.

If possible remove the ribs on the lower plate so the top plate sits on top withoutgaps

 

[DrNik]

i think my welder is backwards, if i have it at 30% the pool is great, no bits, but turned up to 65% it doesnt clean at all, when i was lap jointing i was doing it smooth side facing together, but it should join up with a nice tight 90 degree joint, mig welding is so much easier...... loving the tig as it looks great as a piece of furniture in the workshop,having a welding rep from a local company to come and show me all about itand then just need the next 30 years to master it but thanks for the info,its all greatly received.

 

[ajlelectronics]

Knowing nothing about TIG, I'm not qualified to comment, but I wonder if electrically bonding the two plates together would help the arc heat evenly.

 

[sonamor]

http://www.migatronic.com/product f...e site/Manual/501132xx-501137xx/50113200.ashx

May help.

 

[DrNik]

AJL, once 2 plates are touching and ive some sort or tack weld, wouldnt they be at similar potentials????

 

[ajlelectronics]

Not really, the current being passed through the tack may be insignificant for the current required to establish a stable arc. It's all about impedances. Think about how thick your earth cable needs to be. I would be keen to use a jump lead to bond the plates properly and test the theory.

All that being said, remember that I have never tried TIG so my comments may be of no relevance whatever!

 

[hotrodder]

It doesn't really make much of a difference with AC TIG, with the two pieces clamped together and 'grounded' via the table, one return clamp or two the arc can and will still dance around for the initial tacks. Once it's tacked (and assuming you strike up on a tack) the arc will behave itself. I've always put this down to the fact that the polarity is changing many times a second... leccy always takes the easiest path, with a fillet (including lap) weld you've got one cut edge and one solid piece as Shox said (impedance/resistance/heat needed to melt a corner versus solid lump etc). You're also trying to melt the apex of an imaginary triangle which is why in the arc length demo thread the long arc length resulted in two weld pools rather than the root melting- the easiest path was physically shorter. Strike up on an tack and the area is hotter/cleaner/physically closer than an untacked section

 

[DrNik]

thanks so far for the assistance, i had a guy come out today from a welding supplies company, well he spotted a problem straight away, i was using a brown electrode, good for stainless,bad for ali, unfortunatly the only other electrodes i had was violet/blue, the guy didnt recognise it as a standard colour, but it does weld much better, i can now once its tacked.............Weld ,
i need to get some multipurpose gold electrode unless you guys know better, bit wobbly welds but that takes time and patience, can i use a guide to use to keep torch straight and distance preset??? would it help??

Much to all for help

Still like Nick to maybe pop over to see if he has any tips/hints

 

[hotrodder]

Brown is the US colour for zirconiated (white in Europe) which is an AC specific flavour.
Red is the usual colour tag for 2% thoriated (also available in yellow to denote a different %) which makes more sense as thoriated are kinda DCEN specific i.e. prone to splitting and tend to melt weirdly with AC
Blue is either 2% lanthanated (1% is black, 1.5% is gold) or a mixed flavour. Like ceriated (grey in Eu, orange in the US) they're all happy with DC and AC although ceriated tend to be a love or loathe 'em type of deal- personally i think they're pointless both literally and figuratively
Green is another AC specific one, relatively rare these days it's pure tungsten and balls up lots

With the exception of thoriated for AC and/or zirconiated for DCEN i wouldn't worry too much while learning, the differences between the flavours can be fairly subtle and are as much about longevity between regrinds as anything i.e. become more apparant when you've got past stage of regularly contaminating 'em with the weld pool/filler wire etc

 

[Shox Dr]

Agree with HR. I tend to use white, and won't go near grey, don't know ifi had a bad batch but couldn't stop it from either splitting or getting cauliflowers

 

[matt1978]

HR is spot on with his descriptions.

However I can't see why changing the Tungsten colour/type would of made so much difference to the welding result. Did anything else change?

Most modern inverters will run any colour on AC or DC within reason

 

[DrNik]

no nothing else changed, but its amazing that it made it so difficult, bought 4 gold tungstens now, so i cant forget which one to use

 

[pedrobedro]

Your blue tungsten is probably 2% lanthanated which is ideal for AC and DC and should be as good as gold multi strike if not better.

 

[DrNik]

ran a few lines today, well its great the lines are a bit wobbly but nothing a files can sort out, its only a guard for a saw so no-one will see it

 

[Paul.]

As others have said I also prefer zirconiated (white) tungsten for ally, for your lap weld you need to point the electrode at the bottom plate to get that hot before you allow the arc to touch the top plate, get a tack on to bridge the plates then use that as a platform to weld off,
,

And something to aim for
Although done with an inverter, the settings for this were 2.4 tungsten, 100 amps, 50% balance and 50hz, gas at 6lpm, so basic settings that a simple transformer set would give you, all bells and whistles turned off, I was using a lens but on a joint like that would expect the same results without one.


Don't get carried away over welding your guard, unless things need to be water tight then a few neat stitch welds are more than adequate, and will reduce distortion /overheating and the chance of something going wrong, here's a blade guard I made a while ago.