TIG steel with AC?

[evfreek]

Hi. I just bought a welder on craigslist for a very reasonable price. It was not advertised as a TIG welder, but it came with an HF box, a TIG torch, thoriated 1/16" tungstens, and a reg/flowmeter. Unfortunately, it only produces AC.

Can this machine be used to weld steel? I looked at the Miller guidelines, and it said that 1/16" thoriated 2% can be used from 60-120 amps on AC, nearly as much as for DCEN. I tried putting down some beads on sheet metal with some filler rod. Looked like decent fusion/penetration, even though I was welding in the wrong direction (away from filler). Now that I read the Miller site, it is clear that a push technique has to be used.

The beads had some start-stop craters (no foot pedal and I had a hard time feeding the filler with a gloved hand). Made a funny noise. But it doesn't seem to say much of anywhere on the web that AC can be used on steel. Is there anything obviously wrong with this?

[HWooldridge]

DC allows more heat so is usually employed on steel, titanium, copper, etc. AC is used on oxide producing metals like aluminum because of the scrubbing action. So, AC is not the best choice but can be used on steel in a pinch. When I first bought my rig, I tried DCEP, DCEN and AC on steel (just for fun) and there are differences.

The funny noise is probably the high frequency.

[Timekiller]

Just a tip about filler metal and gloves...

I was using a tight fitting leather glove to move filler, which worked great, but it was then brought to my attention the safety issue with the gloves. If they caught fire, I would be in big trouble, and after recently seeing my friend get 3rdº burns on the top of his hand (not welding) I decided to look for a more suited glove. Tillman makes a real nice TIG specific glove. Thin and loose for safety. With these I had almost the same "feel" as with the tight leather gloves.

[Glenn]

Timekiller
Go to the top of the Forum page and click on User CP
Click on Edit Profile
Go to the bottom of the page and enter your location.
Save.

It will add your location to your posts.

[welder19]

Glenn, can't you just make location a required fill box?

welder19

[eburgblue]

??????? Glenn..... your profile is not showing location..........??????? other than IforgeIron..... I don't get it......??????

[Glenn]

That is where I seem to spend most of my time

The location of IForgeIron is at the bottom of most of the site pages.

[Hillbillysmith]

You can use AC on steel, but DC+ is preferred. Stick and TIG machines use constant current and yo can use an AC stick welder, right?? The only difference with stick is the flux on the filler rods, but with TIG, there are no fluxes. If you're worried about penetration, weld up a joint, I'd do a lap joint, let it cool, and break it. Don't make the weld too big and only weld one side but after breaking it, look at the to plate and If there is a jagged line, which shows where you tied in at the root, then you pass the test. If there is a distinct straight line, where the weld didn't fuse properly to the root, you fail. Just practice until you pass. Do it again with a different joint, different position. If you have any Q's about the testing, just ask. If I don't know, I'll ask my instructor. He's a certified welding inspector in several area's.

But here's my best advise: GET A FOOT PEDAL!!! Or at least a rig with a finger rheostat so you can regulate the amperage.

[Dr Dean]

How about a picture of your new welder. If I had to guess it's probably a stick welder with a HF box added on. If that's the case most likley there won't be any way to add a foot pedal or fingertip control.

[evfreek]

Hi fellas. Thanks for the great advice. HWooldridge, I am glad that I can run on AC until I get a DC welder. I tried welding DCEP in welding class once, and the heat really builds up on the tungsten and balls it up pretty quickly. Also, the charts show that max amperage is pretty low for this reason. AC is confusing, though. I ran a couple of beads, and rounded my tungsten pretty good, but I must have accidentally touched it without realizing it.

Timekiller, thanks for the tip about Tillman gloves. The kind of glove seems to make a big difference in feeding the filler. I will go to the local welding store to pick up a pair. Don't need much of an excuse to go, since it is owned by a blacksmith and the boys there are great.

Hillbillysmith and Dr Dean, you are probably correct about the foot pedal. This welder is a cobbled together stick welder, and does not have a foot pedal. The only thing TIG about it is the torch and flowmeter, as well as the HF box. A foot pedal is not difficult. I have all the parts for one; just need to put it together. They work a lot like those cheap router speed controls, with a special hysterisys and balance circuit for the inductive load. I have a better torch (Weldcraft wp17) but it has no accessories, so it is idle.

The beads I made look good, if a bit wobbly. I even burned through once. The interesting thing is that if you burn through, it is much easier to fill the hole than it is with stick. Filling a hole in sheet metal with 6013 almost guarantees me a slag inclusion. When I set the current a little low, the bead rode too high, just like stick.

This is fun. I was a little leery about the per foot argon cost, but it is worth the ride. I'm on my second tank now .