New to TIG.....

[ShopTeacher]

Hey guys, new to the board but really enjoying viewing all the tips and help that is offered. I'm a high school welding teacher (I am a Machinist by trade) so not a great deal of welding experience and I have a 250DX that I just got running in my shop. I am having trouble getting a decent weld.

I am just messing around with some 1/8 & 1/4 mild steel, using a red band tungsten, DCEN. Any of the calculators that I look at and also the manuals say I should be using about 200 amps or so for the 1/4".

I started out at about 125 amps with the 1/8 and found that it really heated and melted the steel. The whole thing was glowing red including the tungsten.
So...I kept turning it down and trying it.

Basically now I am down to about 65 amps on the digital readout, using 1/4" mild steel and it's not working too bad but I think it should be much better than what I am getting.

I am hoping and based on what I have been reading here is a few of you could offer me some advice on what I could be doing wrong.

Looking forward to your posts...

[tnjind]

No offense intended, but why is the school corp. making a machinist be a welding teacher, that has no experience. I think you are being pushed to teach something that takes years to master, let alone teach to the future of our country.
This board is full of very knowledgeable people that is always helpful. I am sure someone will provide the info you are looking for.
Please don't take this as a"slam" I do not intend this as that. I hope you succeed.
Good luck.

[tnjind]

I just reread my reply. It sounded pretty bad. Sorry. Please ignore.
My bad.

[ShopTeacher]

No offence taken whatsoever. Basically, the powers that be believe that if you have "a trade" you can be "a shop teacher"...frustrating to say the least...
I am comfortable with stick and MIG its just the TIG that is new and I really am interested in learning it.

Really, I appreciate any and all comments - no offence taken.

Tim

[Dustyhaze75]

go to the resource section on this site, then go to improving your skills, then go to the tig welding material. there are videos under hints and tips and there is a full downloadable tig book in there as well. how did you grind your tungsten? the tungsten could be contaminated. for 1/8 " steel you should be runnin at about 140 amps. when I weld 1/8 " steel i get a puddle going then I back off the pedal a bit and control the heat with the pedal. hope this has helped ..................................

[ShopTeacher]

Thanks for the info, I have checked out and read a lot of this info. I am grinding the tungsten the proper way - it could be contaminated though.

I am starting to wonder if the handle could have been installed wrong on the front of the machine. Reason is, according to one chart I looked at, DCEP should be running at about 30-50 amps. It seems to work better and it doesn't turn the whole piece cherry red.

I'll keep trying though...

Thanks for the help.

[HMW]

I use DCEN for steel. AC for alum. It would seem that DCEP would heat the electrode up to much. It doesnt matter how high you set the welder. Set it at 200 if you want. Unlike MIG or stick, TIG will only apply as much amperage as you push down on the pedal up to the what you set the machine at. You should probably just try making some weld puddles on a piece of flat bar. No filler, just make little puddles. That way you'll get practice with the foot pedal. Push down pedal and puddle gets more fluid, let off pedal some and puddle gets more solid. With TIG you can hold a "wet" puddle there for as long as you want by controlling the heat with the pedal. Then add some filler and make little "caterpillers" Weld beads that resemble caterpilllers. All just on a flat piece of steel. Good practice. Don't know if this helps or not but good luck

[ShopTeacher]

Thanks for the input, I tried again today - had a little more success. Used a piece of 3/16 flatbar, ground and cleaned all of the scale off of it, removed about a 1/2" or so of the tungsten to get rid of any potential contaminents there and it seemed to work better. I had the machine set at about 140 amps or so and it wasn't too bad.

This is probably a obvious question but is it normal for the tungsten to be glowing orange during welding? I am assuming so...

Thanks again....any and all tips are greatly appreciated!!

[HMW]

Like I said just turn up the amps and dont worry about it. Use your pedal as the amperage control. Yes the electrode gets very hot. That why if you touch it to the weld puddle or bump the filler against it, it instantly contaminates it.

[ShopTeacher]

I just spent the last 20 or so mins. practicing some more with it and its coming - slowing but surely. I can keep a nice puddle going with no filler and even tried a little filler at the end just for fun. It will definitely take a lot of practice.

Thanks again

[HMW]

You got it just keep making puddles.......

[Dustyhaze75]

ya .............. weld steel with DC strait polarity (electrode negetive ) if you weld with DC reverse polarity (electrode positive) the tungsten may melt before the base metal because about 70 % of the heat is at the electrode, not at the work. penetration of the bace metal is poor when using DC reverse polarity (electrode positive). It is best used to weld very thin sheet metal(not aluminum or magnesium). shollow penetration then becomes an advantage. sharpen your tungsten like a pencil for steel and like a crayon for aluminum. ya it's normal for the tungsten to get red.

[safetydave]

more info

Hi shop teacher, it's a different set-up to tig steel then tig aluminum ye s if you should dip or touch the tungsten to your metal it will contaminate your tung so DON'T DO THAT also yes it will get a cherry red when welding but try not to get it to hot or it will start to pop and then your in trouble,so try to keep your heat controled with the foot pedal, kind of like the gass pedaalon your car the more pedal the faster or hotter you will get so go slow when just starting out watch your puddle if it gets to big back off on the heat and add some more filler rod.I did some 1/2" cast iron the other day for a guy and I had my heat set at 175amps useing 1/8" tung and a roller switch on the head of the torch for on-off and it got hot but I just took my time with a couple of pass's and laid it in nice and thick,turned out great the guy was in shock at such a nice weld because some other shop did a crappy to say the least job who was the best in town acording to all the old school weldor's.
hope this helps you? if you need any more shoot me a line i'll see what else I can do for you, best of luck in the classroom.

[ShopTeacher]

Thanks BIG time!!

A big thanks for all of your posts, your experience and knowledge is amazing to say the least.

SafetyDave: I know I'm a long way from ever welding cast iron but just for curiousity's sake, how do you do it?

[safetydave]

New to tig

Shopteacher.
the parts i welded on were 1/2" thick brackets, so what i did was to grind off the RUST & DIRT to get to the bare metal then beveled the ends to create a nice deep groove (make sure they still match up) pre-heated them then spot tigged the corners (tacked in place) then using red tung (can't remember tech term for this) drawing a blank? and nickel filler rod 1/8" for what i was doing then just started to pre heat nice red glow then added filler on one side then switched to other side for a nice root pass around part then let cool for a few then went back over the other side from starting position takeing time to cool a few with each pass until i had three pass's on this part,root,fill,cap. The problem is that now i post stuff and give info on this site i forget to get some pics of the stuff i have done,so i'll hav to remeber the camera when i get a project. I'll try to remember anything else that i might have done to this part and get it to you and see if it casn help you with anything. untill then just keep practiceing on any thing you can.