Aluminium tig problems

[Electric4Life]

OP. Judging from everything you've stated and the picture you've provided I agree that the main switch isn't
1. entirely locked into AC
or
2. the contacts need to be cleaned if it has been set to DC for several years

Good luck sir

[72challengerman]

It sounds like it is not switching over to me. It is melting the material but not cleaning it at all. I will get a piece of aluminium from school put a bead on it with the tig machine there I know works properly then being the same piece home and try it on my machine to rule out the material variable. How do I take the machine apart and clean the contacts to try and get ac back if that’s the issue? When I am trying to use it I’m not really paying attention to the sound bike I will next time I go out to the shop.

[G-ManBart]

It sounds like it is not switching over to me. It is melting the material but not cleaning it at all. I will get a piece of aluminium from school put a bead on it with the tig machine there I know works properly then being the same piece home and try it on my machine to rule out the material variable. How do I take the machine apart and clean the contacts to try and get ac back if that’s the issue? When I am trying to use it I’m not really paying attention to the sound bike I will next time I go out to the shop.

The way the selector lever works the contact points can't be touching both AC and DC positions at the same time. If you're getting an arc and enough power to melt the material you're getting current passing through the contact points. It won't hurt to clean them, but they make pretty robust contact, and the way they're shaped they tend to scrape off any corrosion that would be there from sitting over time.

Remove the side covers and top cover completely. Then look at the left side of the machine, right as you look at it, and you'll see the brass colored tube that connects to the selector handle. That runs back to a set of brass colored contact fingers that are like blades set in a T shape with each group 90* from the other group.

I didn't take this picture with this in mind...look for the blue canister at the top (silver on some machines) and just below and inboard of that you'll find the contact points. I simply hit them with compressed air, sometimes a dry paint brush, then wipe them with dielectric grease and have never had to do anything else.

[72challengerman]

Ok. If I clean them and the problem persists, what else could it be? I would like to fix it myself rather than take it to a place that services equipment.

[72challengerman]

Ok I’m out in the garage and have got some more info. When I put it to electrode positive it cleans the metal but doesn’t melt it really and balls up the tungsten. When I turn it to ac it doesn’t ball the tungsten but makes a buzzing noise. When I turn it to electrode negative aside from the noise it makes the exact same weld as when I put it in ac mode, no visible puddle. When I am not flooring it on ac mode it flickers on and off. When I give it lots of power it seems to stabilise but still isn’t perfect. So no cleaning action in ac mode and an arc that isn’t really stable and requires lots of amperage to keep it from flickering on and off. I’m totally stumped. I doubt it’s getting very much of the electrode positive cycle if any at all. It is set to continuous high frequency. Any help is appreciated.

[ASKANDY]

If you have a multimeter, you could check a couple things.
What is the "open circuit voltage"? This is checked with the HF switch in OFF. Put your leads across the output studs and step on the pedal.
That machine should have digital meters. Make sure the voltage on the multimeter matches the machines digital meter. I think it should be around 60 volts AC. I'd have to look up the voltages specs to be exact but if there is a problem with one of the SCRs, it will be very low. Like only 30V.
You really need an oscilloscope to troubleshoot this properly. It will tell you if the AC is correct and the SCRs are firing properly.
It still sounds like bad gas to me.
Have you tried a known good bottle of 100% ARGON? It doesn't take much contamination in the bottle to create this problem you are seeing.
The other thing that causes this is a contaminated torch or torch parts.
I can't tell you how many times I've cured this problem with new collet, collet body and cups.

[WillieB]

I haven't read it all, Forgive me, but black soot is gas coverage failure. You can get it many ways.
Wrong arc length.
Air leakage in torch or lines.
Tungsten contamination.

If you don't have a failure in gas delivery, you are cooking too log to form a puddle. Hit it fast with full pedal, very short arc length. Tungsten wants to be 20 degrees off perpendicular to puddle.

If you dipped your tungsten, it must be cleaned. I like a dedicated bench grinder laid on its back. It pulls the grindings away from you, eliminates the risk of stubbing & throwing it at you. I grind from up the shaft about where the collet will touch it. clean off any residue, form a blunt point.
I have two grooves worn in a fine wheel, I follow up with the cleaner groove.

Don't use a grinder on aluminum you will weld. Aluminum melts at low temperature. Grinders tend to mix crud into the metal. Stainless hand brush, or just acetone wipe.

Don't need pure tungsten or a ball with square wave.

[72challengerman]

Ok thanks guys I will check the over current voltage later today. I don’t think it’s bad gas, is there any way I can check? I will try switching over my collet collet body and cup later today to see if that fixes anything and a fresh piece of aluminium. My machine does not have digital meters on it.

[Ltbadd]

I don’t think it’s bad gas, is there any way I can check? I will try switching over my collet collet body and cup later today to see if that fixes anything and a fresh piece of aluminium. My machine does not have digital meters on it.

Only way to check the gas I know of is to try another bottle

If you're using inexpensive collets and bodies then I would suggest using CK parts, not really that much more $$ but CK is top quality.

Do you have another torch to try?

[WillieB]

Welders like to blame gas. It could happen in theory, I've never seen it. Empty tank gives those symptoms. The regulator flow meter shows adequate, but tank pressure is low, it'll act up.

I near always use a gas lens. It's only a diffuser similar to aerator on kitchen sink faucet. It helps to reduce turbulence. You want gas to displace air, not go jetting off. I like a gas lens.

There are corner or gap situations can cause bad gas coverage.

Shovelon suggested a flow meter to use at the nozzle. I was surprised how far wrong my tank mounted flow meter was. I now trust the work end flow meter.

[Aeroweld]

A couple few comments and observations.

Do you know the grade of aluminum you are using? It almost looks like it is 7075 or maybe 2024 or it is an anodized aluminum. Still useful for practice but it won't melt the same nor give the visual clarity or crispness of the puddle as say 6061 material will

If you are going to clean the surface with a grinding media it needs to be aluminum oxide. Silicon carbide media will embed itself in the surface and that could be one of the reasons you are getting the black soot. If the material was anodized it will also give off black soot and a "sluggish" puddle. Use only grinding media recommended for aluminum and don't cross contaminate with other metals.

Kick your argon flow up to about 20 cfh and make sure there is no breeze to displace the argon shield.

I think I read you were using a #6 cup. I would go to a #8. You need enough stick out of the tungsten to see the joint and if the cup is too small you will lose gas coverage especially when using the 1/8" diameter.Tungsten.

You didn't mention how you prepped the Tungsten. If you are trying to weld with a piece of Tungsten "Out of the Box" you need to put a taper on the Tungsten. As to the size of tungsten for this exercise, I would probably go down to 3/32 but 1/8" will work. I would go to about a 4:1 taper on the 1/8" and maybe about 2:! or 3:! taper for the 3/32 tungsten. You want it almost to a sharp point. Don't get overly concerned about balling the tungsten. If using Pure it will ball itself especially starting with such a pointed tip. I know someone posted the recommendations from a manufacturer and one of the points they mentioned was that 2% didn't maintain a ball end but that is exactly why I prefer 2% Thoriated as the ball doesn't grow much once it is formed and makes control of the arc easier when doing fine welding. I've been doing Aluminum for 45 years and 99% of it was with 2% Thoriated on Transformer machines. .

I know some have said to just jam the pedal to the max to start. That has never worked for me. If you have a contaminated surface you are just adding to the problem If your machine is set at 150 amps feed the power in slowly. Start with about 1/2 pedal and look at the puddle or lack of. Start adding more heat until you start to see the surface melt. If your base is contaminated the garbage will start to boil to the top of the puddle. It will appear as black flecks floating on top of the puddle. If you are just slamming heat into the material you will never get the proper read of the puddle. Add in more heat until you can see the clean shiny surface and the garbage is boiled out. You might have to stop and re bush the area with your stainless brush and start again. Once you have a puddle established then you can start adding the filler and adjusting the pedal to keep things flowing.

I hope to have been some help
Mileage and results will vary.

[G-ManBart]

Welders like to blame gas. It could happen in theory, I've never seen it.

I've had three bottles that were contaminated so far. All three had just come back from hydro with a new valve, new paint, and new stickers. They came from two different suppliers but I believe they were all tested at the same hydro shop. I suspect they had something other than argon in them previously and they didn't do the proper evacuation process. Two were awful and acted almost as bad as forgetting to turn the gas on. One worked fine on steel but turned awful on aluminum. In each case I could switch to one of my other tanks with no other changes and things were normal. It's probably not too common, but my friend who owns a welding shop usually has a bottle or two marked "bad gas" in the return cage and said it happens pretty regularly, but mostly when they change what gas is going in the tank.

[Electric4Life]

Contamination (bad gas) is more common than a lot of people realize