96 Comp T/A

iTrader: (8)

Hey Gent's,
I need some help from those of you who have welded stainless. What if any changes do you make when going from mild steel to welding stainless. A buddy of mine has an Invertec (DC only) with a high frequency starter and remote setup on it. After about an hour or two of practice, adjusting amperage and general experimentation with the various ***** and switches, our practice welds with plate steel look awesome. We are really pleased with how it's turning out. We now want to tackle stainless steel. We had some polished stainless tubing from an aftermarket exhaust system lying around. So we cut a piece of the pipe and attempted to weld it. Somehow the Tig torch starts acting like a plasma cutter. I am barely on the pedal for a second and I have already torched a dime sized hole in the material. We have the amps turned down to 1.5 on a 1-10 scale. We have tried reversing the polarity which destroys the tungsten AND the material as opposed to just the material. There are two more rotating ***** and a switch for 2-step and 4 step on the remote box (that handles the hi-freq start). One of the rotating ***** sets the gas flow period after you let off the pedal. The other looks to be for adjusting the rate at which the amperage tapers off when you let off the pedal. What does 2 step or 4 step do? Any recommendations would be appreciated. I really don't want to have to mig weld my stainless headers together.

jimmyblue

iTrader: (11)

Sounds like a gas problem to me; maybe the gas solenoid
stuck shut or the control quit on you. Or the bottle just
ran out?

NOSjohn

iTrader: (9)

What size is your tungsten and what thickness mild steel were you welding? It sounds as either your tungsten might be too large for material or your having a gas shielding issue.

96 Comp T/A

iTrader: (8)

I will have to measure the tungsten size tonight but off the top of my head it' s about 1/8' diamter, the steel we were playing with varied in thickness, anything from .065 exhaust tubing to 1/8 inch and 1/4 plate steel no problem. After burning a hole in the stainless I can go right back to welding steel without any problems. It's a full bottle of argon. How far should I have the tungsten sticking out of the gas shield? We have it out about even to an 1/8 inch out. What about distance from the material? I am holding the torch about 1/8 to 1/4 away to get it started. Anything more will put a lot of heat in the material to start with. Thanks for all the help!!

NOSjohn

iTrader: (9)

IMO, a 1/8th tungsten is too big for welding 16 gauge SS. Try a 1/16 or 3/32 Tungsten which means you'll have to buy a different collet. Tungsten should stick out 1/8th - 1/4 inch from the cup.

jdustu

iTrader: (2)

ideally you may want a smaller tungsten, but you can get by with a larger electrode if you use a long taper and pretty small point.....

4 step is good if you need to scratch start or aren't adjusting the amps remotely.....then you can use the slope up and slope down features.........do a nice slope up and that may help your problem....

i'm guessing you aren't adjusting the amps remotely?? then you pry want to try the 4 step and mess with sloping the current......keep the gas pressure so that you can barely feel it at about 4 inches from your face(pry 15-20) and make sure the gas is coming on before the arc strikes.....remember if you get into any serious stainless welding that butt welds and the like should be back purged with argon....if not the back of the weld will sugar from the chromium burning out and it will be contaminated and rust


i've only used a 4 step machine a few times at our tech center, so maybe someone else has a better idea of exactly how to set you up......

96 Comp T/A

iTrader: (8)

Ok Gents, I did some more experimentation last night. I think there is something wrong with the remote unit. I can never draw any more or less than 48 amps. I didn't measure the tungsten but I did notice that we are successfully welding steel with a #6 shield and tungsten. I did try a #4 tungsten and shiled which is about the size of a piece of lead from a mechanical pencil. Any time we struck an arc with it it would vaporize the tungsten. So I started to weld some steel again and my buddy was watching the amp draw gauge. What we discovered is that no matter what the pedal position was or what the amperage **** on the remote is set to we only are getting 48 amps. We checked the manual and we have the remote configred correctly (per their recommendations). Can anyone briefly explain how to scratch start? I want to remove the remote unit from the equation and see if I can get the amperage to vary.

jdustu

iTrader: (2)

i haven't done much scratch starting, but i've heard the best way to do it is to lay the cop down parallel to the work surface, then tip the tungsten towards the surface until the arc starts......


this may sound like a dumb question, but is the machine set to remote control? there is probably a **** for panel control or remote control, if it is already set to remote then maybe the switch is broken?

99.9percenter

iTrader: (2)

Scratch start is about the same feel as striking a match. If your sheilding gas is up too high it will create vortexes and suck in air and contaminate your weld. What type gas do you have? What is the flowmeter set to?

96 Comp T/A

iTrader: (8)

100% Argon, currently set to 20 lbs/Min.

96 Comp T/A

iTrader: (8)

The toggle is definitely set to remote. We also tried adjusting the amperage from the dial on the main box and nothing changed then either. In remote it is supposedly deactivated anyway.

99.9percenter

iTrader: (2)

Try 10lbs/min I am used to thinking in cubic feetper hour or litersper minute I think 9-11 liters per minute is right. What is the volume of a pound of air? The flow should not be much differnt than a human normal breath.

Silverback

Huh, I could have sworn that I read this someplace else…

I had a thought looking at it here though… any chance that that piece is not stainless but something chromed?

96 Comp T/A

iTrader: (8)

It's polished stainless, if the polishing makes any difference or not I don't know, but it is definitely not chrome. I haven't had a chance to screw with it much this week but I am going to call around this weekend and see if one of the local welding shops can take a look at it. The equipment was purchased used from a manufacturing facility that was moving to a new location and purchasing new equipment in their new shop. It was used to weld together stainless material for large food processing machines so I know the machine is capable of doing stainless. We were told the equipment was in top notch shape when it was purchased.

1fastWS6

iTrader: (3)

I've never done anything different between stainless and 4130 or mild steel. Is the metal dirty or does it have polishing compound on it? Cleanliness is very important also when TIG welding.

96 Comp T/A

iTrader: (8)

I've tried roughing up the surface with a roloc disk. Same thing.

jdustu

iTrader: (2)

yeah, it definetely sounds like something is set up wrong or is busted......one reason it would work on the mild steel and not the stainless: it sounds like what you are saying is that the current is not changing, so while its on the low end for the thicker mild steel, the steel absorbs the heat and eventually heats to where you can lay a nice bead; but for the stainless piece the current is way to high right from the get go and blows right through it.......even in remote the dial should give you your current, right? i wish i could be of more help, but i have no experience on the dc only inverters.....or inverter welders in general.....whatever is happening sounds like it is due to the current not changing.....

Lemco

iTrader: (2)

Where are you located? What kind of rod are you using?

jdustu

iTrader: (2)

if he's blowing a hole through the stainless as soon as the arc starts then it doesn't matter what rod he's using......

m-port-h8r

We have almost the same problem with one of our older Syncrowave 250's at work. You set the panel to remote amperage and remote output, you set the dial to 50 amps (about 1/4 output). You depress the pedal fully should only give you 50 amps. The problem with ours is that if you depress it full it's welding at full output (310 amps ) no matter where the dial is set. So some of the students that I teach aren't aware that you need a light foot on that machine and they end up burning up cup's, tungstens, and their stainless pieces.

We've had a Miller rep come out and knew exactly what the problem was. I think he said the master output switch was bad. Aparently it was a warrenty issue. Their new machines have the problem resolved. To fix it was going to cost $600 for the part + one hour of labor.

Burning stuff up would tell me no gas or amperage to high.
Also when welding stainless you want to use just enough heat to get a molten puddle. Any more heat will result in contamination and suck back.

FWIW: The tungsten should be the same diameter as the metal you are welding. The tungsten stick out should be no greater than the cup diameter. The cup diameter should be 4 times the diameter of the tungsten (1/16" tung = 4/16 or 1/4" or #4 cup) Post flow should be 1 sec for every 10 amps.
These are general recommendations.