Technical Mig Welding Problem

I'm having a problem with my mig welder......or its having a problem with my welding? Anyway, you know how your welds look when you forget to turn the shielding gas on. Its got that moon crater look.
Tried switching 75/25 tanks and that didn't help. Tried increasing gas flow. Tried taking another tank and holding the open hose next to a weld and flooding it with 75/25.
Listened to see if gas was flowing when I pressed the trigger. I could barely hear the gas noise, so I asked my wife to listen. She could hear it faintly. The guage does the little flicker when I start welding. Tried changing the regulator.
The hose from the bottle to the machine flows good when disconnected. I'm going to try changing the wire spool later today and see if I have some bad wire. The wire was working okay before this started.
If the wire doesn't fix it, about the only things left are the passage in the hose to the gun or the valve control in the machine. This is a high quality machine and is only a year old. Any suggestions on what the problem might be ? How loud is the gas noise when you start your welding gun.....normal or faint?

 

Any chance you have the cables in the wrong position ?If you have been welding flux core,and you forgot to switch the cables for welding with gas you will find your machine welds like crap.Check the polarity.

 

Anything drop on the hose?

 

You might want to check the nozzle to make sure some welding splatter hasn't covered some of the holes.

 

Pinched hose?
Makes sure the cable is as straight as possible,
In my Lincoln you can clearly hear the gas hiss when you pull the trigger.


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I can't hear the gas on mine at all. Maybe I'm just old and losing my hearing though

 

If you turn up the gas at the gauge regulator, You should be able to feel a good bit of gas exiting the nozzle. Id liken it to the pressure coming out of a straw when blowing through it.
No pressure?? then remove the liner, Blow out your liner and your whip with an air compressor.
Reinstall. A lot of times graphite will clog the whip causing this condition.
Still no pressure? Then it may be the electric valve switch.

 

Mine was doing the same and found the plastic hose popped off where it connects to the liner. Replaced the spring clamp with a geared clamp works like new.

 

Soapy water check for leaks?
I have gotten bad gas before.
There is a mix for stainless that includes oxygen.


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Clean the weld splatter out of the cone, and it is a good idea to clip a piece of Scotch-Brite pad around the wire where it enters the weld lead to clean it and not pull the crap into the liner!

 

Not a Scotch-Brite pad. There are felt pads made for that, by Weld Aid Products and others. But that doesn't have anything to do with gas flow. Good suggestions above. Is your cylinder all the way open? It should be. Loosen the drive roll and pull the trigger (so gas flows but no wire). Adjust the regulator/flowmeter to 15-20 range. The gas nozzle should be flush with the end of the contact tip, or just slightly past, 3/32 or so. How far are you away from the work piece? Too far and the gas just blows away. Got to be pretty tight.

 

Damaged equipment, not having the flow set high enough, the regulator on the bottle could be defective.

A defective gun trigger or clogged liner all these things could be a possibility.

The gas flow solenoid inside the machine could also be defective.
Check it out step by step, usually easy enough to find the problem.

 

I had what sounds like the exact same problem and it turned out to be the magnets I was using to hold the two pieces together that I was welding. They were so strong they were interfering with the weld. Changed over to a couple of clamps and a block of wood for positioning and all was well. Took some doing to figure it out including replacing a cylinder of gas!

 

If your gas flowmeter is showing flow, 20 cfh or so and the gas is not getting to the nozzle, then you have a leak. Probably inside the gun cable. Some guys are not very careful with them and they are sort of delicate. Don't run over the gun cable, ever. Don't roll the bottom corner of a new gas bottle over it, if something heavy and sort of sharp falls over on it, it's probably damaged. If you are showing flow the gas is going someplace.
If flooding the weld zone with gas from another hose didn't fix it, you have probably a problem with the wire or the metal. Is the metal free of oil and paint? What wire are you using, does it use a gas shield along with a flux core? If so, the flux core may be loaded with moisture. Also, it seems too simple, but are you sure you are trying to weld steel? If it's magnetic, is it some weird alloy?

 

I accidentally pulled the cable out of the machine once, not enough that it wouldn't feed the wire, but enough that the gas would not flow. It was all under the dust boot so I did not notice when I did a cursory look at it. Pushed it back in and tightened up the set screw and forget about it for another 10yr.

 

I will assume you are welding inside and not outside in the wind. did some outside welding a few weeks ago and had to build a little fort out of cardboard sheets to protect from the wind.

 

I bought a new “ blue” 250 mig welder and had trouble with it from the start. Had several people look at it and try to weld with it. Nobody could figure it out. Finally used up the tri gas and was filling it, the guy asked why I was using tri gas, I told him I was told it’s the best. He sold me some CO2, it was like another different welder! While it never really seemed right , I was able to finish my project. Just my experiences.






Bones

 

I would start at the tank with no regulator and crack it open and you should get a blast of shielding gas. Next just the regulator and see the flow. Next disconnect the hose from the gun and check it. All I'm doing is a step by step process to see where your stoppage is. Let us know what you find.

 

I have been out in the shop earlier and took a cursory look at the welder. Got the manual out and went thru the set up steps to make sure I hadn't inadvertantly changed something. Tried welding again and had the same problem. Lots of info and suggestions here and I appreciate all the help. I'm tired and don't feel like going back out to the shop to experiment some more today, so I'll try to address the more common suggestions and then work on some of the others tommorrow.
I don't use flux core wire. There isn't a problem with wind as I'm indoors and not using a fan. I have one of the little round things that you put a special lube on and slip it around the wire. I am not using any magnets. The steel is just common cold roll plate and is clean.Its not a spatter problem as I changed the tip. I wondered if the wire might not be bad ? Something I did notice is that the voltage meter jumps up and down while welding. Usually you have the mask on and don't see what the welder is doing cause you are looking only at the weld. I left my mask off and just held the gun down against the metal and the meter went crazy. Here is what the "welds" look like.

 

Maybe I missed it, but what kind of welder is this? size/brand

Also, do you have a flowmeter or a gauge? What is either set at, and what does either move to when the trigger is pulled and held for a few seconds?-no need to weld, just cut the excess wire afterwards.

 

Curious how much wire you've run thrue it in the last year?
I've seen the gun liner cause problems, even when not very old.

 

I don't know what metal you're welding but that stuff looks dirty, something mig welders hate, Take a grinder to that, clean up a nice clean shiny spot and try again. The porosity is gases trying to escape the hot weld, meaning its dirty under the weld. Mig welders love clean freshly ground material.

 

Diaphram in the regulator could be bad. Looks to me like you're NOT getting good gas coverage. IF there is paint/rust/oil/do-do/whatever on the metal you won't get a nice weld.
Looks like the heats good....wire feed good(maybe a little fast)...
Wipe the metal with acetone or Laquer thinner (NOT/NOT Brakleen!) and try it. If still no joy.....I'm bett'in on a busted gas regulator. (sometimes the chinese prisoners/children do a crumby job of building)
Here's a cartoon fer ye to make you smile.
6sally6

 

Take the end of the gun apart.
Cup, tip, tip holder/ liner retainer.
See if you get gas now. If we do get gas flow then clean those parts
Or
Next take the lead out of the machine and check the O-ring . Hook up the trigger wires and see if you get gas flow there at the hook up socket. If you do get gas flow bring the cable housing and liner and all those other little parts.
If not gas then check out the gas solenoid

 

that last bead looks like no shielding gas.

 

I’ve seen nozzle dip plug up the little gas holes

 

How old is your tank of 75/25 and how long has it been since you last welded with it? The reason I ask is that I once had a similar problem. I changed the liner, the wire and the rollers, flow meter too... still the same problem... porosity. After pulling my hair out for a few days, one of my neighbors comes over ( he's the GM of a major welding supply company) to see what's going on and I told him exactly what was going on and what I did. He said to roll the tank around on the shop floor for a few minutes, the gasses probably fell out of suspension. It had been a while since I last used it so it seemed plausible. Sure as shit, I rolled the tank around for a few minutes, put it back on, and bang! Nice smooth welds again! Sorry for the long winded response, but it's something to try that doesn't cost a dime and just might solve the problem.

 

See these brass parts?
See the little holes in them?
That’s where your gas comes out into the nozzle cup.

 

Could also be caused by laying the gun down at too much of an angle. That messes up the gas flow and can induce air into the shielding gas. The gun should lead the puddle at an angle of no more than 15 degrees off of vertical (or perpendicular to the puddle, depending on the position of the weld).

 

Had a situation like this. My welds started to look like yours with lots of porous beads one time it would weld ok, and the next time I pulled the trigger it was crap. Got mad one day and got in my pickup drove to the city and bought a new 252 Miller. Drove home put the same wire and bottle on it and it welded great. The welding store wanted to trade in my old welder till they found out that it was a Century. Then I discovered that the Century had known problems with circuit boards and intermittent gas flow. Probably only two bottles of gas ran through it. I sold it a cheap to a kid that thought he could fix it. Lesson learned to buy only buy Millers or Lincolns. Don't know what you have but ck with a real welding supply co. Maybe they have knowledge of a history of problems and potential fixes on your machine