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Normsthename
02-03-2008, 02:57 PM
I have a NEXUS NXT 250 AC/DC TIG Welder.
I use it to weld mainly Stainless Steel, and a little mild steel.
I have been welding with it for about two years now, having learnt from scratch.
Lots and lots of scary looking welds and lots more practice later, I now consider myself a reasonable TIG welder on these materals.

I would now like to have a go at aluminium welding.
I use pure argon gas, and I also have some ally filler rods a friend gave me to try.
I have had a try at aluminium welding, but it did'nt go very well.
I cleaned the alumium and filler rod before welding.

The manual that came with my TIG welder is next to useless!
Could someone please give me some base settings to get me started.

Thanks

Andy

richardsohn
02-03-2008, 04:12 PM
I have been in the same situation a couple of years ago.

I went to a Tig welding work shop in Griffin GA. Came out of it with everything I needed for AL welding.
First, machine set-up: Most of the time you need a 1/16 Tungsten!

Set the amperage to about a high as you think you need, higher is better.

Welding: for starting, push the controller all the way to maximum and as soon as the two sides of the seem start melting, put in the rod.
Hold the melt bath with the controller. You may have to back off to a very low setting, just keep it liquid and dip the rod in.

If you think you are loosing it, stop and start new on the spot where you stoped, it is generally easier than starting a new joint.

Do not butt weld 6061! it will crack!

I believe the cleaning issue is overrated in the manuals, if everyting else is right it will work, especially with the newer machines.
FWIW.

richardson

The above described would work for starters trying to weld up to 1/8" thick aluminum on a welding table for practicing.
Just trying to give Andy some hints.

richardson

Toysrme
02-03-2008, 04:58 PM
How are we suppose to answer if you don't tell us what you're welding?
Alu? Okaaaaaaay. What kind of alu??? How thick??? What type & position of weld are you attempting? etc...

Normsthename
02-03-2008, 06:10 PM
I went to a Tig welding work shop in Griffin GA. Came out of it with everything I needed for AL welding.
First, machine set-up: Most of the time you need a 1/16 Tungsten!
One of the problems I am getting is that the tungsten is melting before my eyes when I try welding aluminium!
Which makes me think it is a setup issue.

My TIG Welder has a maximum amperage of 250 amps.
So I would imagine it would weld a maximum of approx. 1/4" Aluminium.
I just need a general setup for the Welder.

I got the following setup from the Miller site for doing a fillet weld in 1/4" Aluminium :-

Tungsten Electrode Diameter: 3/32" (2.4 mm)
Polarity: AC (high frequency)
Torch Cup Orifice Diameter: 1/2 - 3/4" (12. 7 - 19 mm)
Amperage Range: 170-190
Gas: Argon
Gas Flow Rate: 25 cfh or 20 psi
Welding Speed: 8 inches per minute
Filler Metal Diameter: 3/32" (2.4 mm)

These are pretty straight forward, it just the setup of the welder regarding all the other settings I need to set, pulse?, pre-flow, post flow, cleaning etc etc that I need help with......


Andy

Weldtutor
02-03-2008, 07:39 PM
One of the problems I am getting is that the tungsten is melting before my eyes when I try welding aluminium!
Which makes me think it is a setup issue.


The problem you state sounds like your machine is giving a DC reverse polarity output.:mad:

Try preflow of 2 seconds & postflow of 5 seconds or more to eliminate electrode contamination.

Normsthename
02-04-2008, 05:45 AM
The problem you state sounds like your machine is giving a DC reverse polarity output.
Is that a setup issue, or a machine fault???
I have the machine set to AC, and it definitely sounds different from when I am welding Stainless etc

Andy

Weldtutor
02-04-2008, 09:16 AM
Is that a setup issue, or a machine fault???
I have the machine set to AC

It could be a machine fault.

Another consideration for AC welding of aluminum, the tungsten electrode is allowed to form a hemispherical ball on it's end.

Do not sharpen the tungsten as is done for DC use with steels.

Normsthename
02-04-2008, 10:01 AM
It could be a machine fault.
Another consideration for AC welding of aluminum, the tungsten electrode is allowed to form a hemispherical ball on it's end.
Do not sharpen the tungsten as is done for DC use with steels.
I did know about the tungsten sharpening for aluminium :)
I think I need to find someone who can weld Aluminium to have a go on my welder with Aluminium.
At least that will rule out a fault with the welder, and just leave pilot error :D

Thanks for your input

Andy

Toysrme
02-04-2008, 04:21 PM
What??? No...
I don't know anything about the Nexus welders as they're English and we do not have them here. That being said stop balling your tungsten. You only ball a pure tungsten electrode for welding on an ancient transformer-rectifier machine that can not adjust the balance of it's AC cycle enough to suit the welding you're doing.
The NXT is an inverter welder. You should be using the same old common 2% thoriated or 2% ceriated you use with steel. Prepaired with a tapered, trunctiated tip exactly like you would for steels.
Doing so is one of the primary benifits to a modern inverter welder as you get much longer tungsten life (as the alloy tungstens have a higher working temp, etc), and because the tip is tapered and trunctuated, the arc is tighter, with much more control. Simply take a thoriated electrode that will not been used on steel and use it for your aluminum. Do not grind it on something that grinds steel if you want to avoid all cross-contaimination.

Because Nexus does not have much information online in their product manuals:rolleyes:, here's what I suggest starting off with however your machine can do it for 1/4" aluminum plate:

Set to AC (duh) with high frequency stabilization turned on (duh)
Use a 3/16" 25 thoriated tungsten at 240-320 amps
Set the balance control to a mostly DCEN cycle. 70% to 65% DCEN
Set the to 120htz

Personally it sounds to me like you're using the dead opposite thing for an electrode as you shuold be (A fast melting pure electrode with a balled tip, with way too little DCEN cycle. Remember, DCEN gives the workpiece more heat in a tighter cone, while DCEP does the opposite in an attempt to strip the surface oxides off the aluminum while you weld)
Lots of DCEN, little DCEP.
That's my general idea anyway.

Normsthename
02-04-2008, 05:38 PM
Thanks Toysrme :)

Set the balance control to a mostly DCEN cycle. 70% to 65% DCEN
Is this the TIG AC Balance?
My manual says :-
In AC Welding this section allows to adjust the cleaning / penetration balance.
Penetration can be adjusted from 15% to 85%


Set the to 120htz
What is this???
Is it Slow Pulse frequency??? if so, what Pulse time, Pause Time & Base Amp (A%) should I use???

Thanks for all the help :)

Andy

Toysrme
02-05-2008, 01:38 AM
Set it to cleaning (dcep) 30% / penetration (dcen) 70% balance.

Two peoples seperated by a common launguage, Im guessing at the meanings so what choices does it give?
Base amperage is the background current.
Pulse time is either the amount of pulses per second, or the amount of time each pulse peak lasts.
Pause time sounds like the amount of time spent on background current.


btw I should add to my other post about tapering your electrodes. By the time you get to around 90-100amps you need to make the grind sligthly steeper in angle, but don't ball it.

Normsthename
02-05-2008, 06:02 AM
Hi Toysrme

Two peoples seperated by a common launguage
I told you the operating manual was useless! :D

According to the manual :-
Base Amperage is the base current.
Pulse time is the amount each pulse peak lasts.
Pause time is the amount of time spent on base current.


Set it to cleaning (dcep) 30% / penetration (dcen) 70% balance.
My welder does not have dcep or dcen.....
It only has the TIG AC Balance
Quote from manual :-

'this allows you to adjust the cleaning / penetration balance.
Penetration can be adjusted from 15% to 85%"

So I guess I should set the balance to 70% Penetration?

Thanks for your input.

Andy

Toysrme
02-05-2008, 09:34 AM
Ya you got it. AC is DCEN + DCEP. When the balance control says Penetration, it's talking about the negative portion and cleaning being the positive.

tool_man
03-20-2008, 02:31 AM
Aren't the inverters great? Too bad the local welding suppliers are still living in the transformer age.I have to order cerriated tungstens online.I find them far superior to the thorriated tungstens for aluminum work.The hardest part about using the inverter tig is having to go back to using the old tig at work.Yes...they are living in the same age as the local suppliers.LOL

mc-motorsports
03-20-2008, 04:03 AM
Aren't the inverters great? Too bad the local welding suppliers are still living in the transformer age.I have to order cerriated tungstens online.I find them far superior to the thorriated tungstens for aluminum work.The hardest part about using the inverter tig is having to go back to using the old tig at work.Yes...they are living in the same age as the local suppliers.LOL

Night and day, the ONLY dis-advantage to an inverter type welder is the price. Everything else is a dream come true compared to an old school "transformer type".

So what do you pay for cerriated online? I think I pay $60 for 10 pieces 3/32", seems expensive, but outperforms Thoraited hands down.

Verfur
03-20-2008, 08:54 AM
inverter vrs transformer type. How the Heck do they get the power from a suit case that used to take a 300lbs welder to even come close. One advantage of the older transformer welders are they dont walk of as easy (to be used as a welder else where) maybe as scrap cooper. LOL Im stuck with the old Miller for now.

mc-motorsports
03-20-2008, 09:27 AM
I would like to know that also. Something about transitors and high speed switching to create high freqency's blah blah blah and you end up with a welder that weighs 1/3 it's transformer type equivilant with MUCH better arc control. Plus every inverter type welder I've ever seen, with the exception of hobby level, has all the bells and whistles, you can dial in the HF, much more control over the AC balance, pulsers that do up to 5000pps, which is excellent for tack welding aluminum!

tool_man
03-20-2008, 12:32 PM
As Verfur said,transformer welders do have advantages.They certainly don't walk away.LOL.I use one at work because they don't have an inverter.I get good results with it.No complaints.I don't know how they pack all that power in such a small package but,I know it works very well.Consider this....not too many years ago computers were slow,large,power comsuming monsters.The computing power of my laptop would have taken a large room,a huge power suppy and an airconditioning unit to operate it.
Portability and versatility are important factors to me.I own a Miller Dynasty 200 DX.Not the largest inverter they make,but adequate for me.It does a great job on aluminum.I can connect it to anything from 120v to 480v 3 phase without having to switch links around.It automatically senses the input voltage and adjusts itself.
Cool right?Anyone who wants to scrap out a tig for the copper is in for a big disappointment.Most I have seen are wound with aluminum.If I owned a transformer tig,I would not mothball it and buy an inverter.On the other hand,if your syncrowave dies(probably never will)check out the inverters.I think you will like them.

To mc-motorsports.$60 for 10-3/32" sounds about right.Expensive yes but,worth every penny.