Ok, Mig welding sanity check....

ChristianHF · Mar 23, 2013

I purchased a new Mig machine 2 weeks ago and have used it both this weekend and last. Last weekend it ran fine aside from occasionally it would act like the wire speed was suddenly slowing without any interaction with the control knob what so ever. Went through the usual diagnostics, didn't make any headway, asked on a few boards and it was suggested I check the liner. Pulled the liner a few days later, found it crushed slightly. So to keep my project going I went to the LWS and purchased another put it all back together and figured I had the problem solved.

So welding today was a little more frustrating. The machine would alternate between acceptable and very porous welds, almost like the gas was intermittently turning on and off. The gas was on the whole time, flow meter was set for 20 CF/Hour, every time the trigger was pulled (that I was watching) the flow meter ball would float up to the 20 CF/hour mark but the weld was behaving like there was no shielding gas. 75/25 argon/CO2 and the same bottle that was making clean, non porous welds last weekend. So again I started diagnosing, checked my ground, cleaned it down to bare metal and tried again. Same result. I checked that the machine end of the gun was seated fully, checked that the o-rings on that end were in tact and they were. Again, intermittent porous welds. I looked at the cable closely and noticed it appeared to have been crushed in the same spot as the liner. From what I could tell from what I was able to find on the internet it appears that the gas flows around the liner in the cable and I have to believe that this is now my problem. I have nothing in the shop that could have crushed either the liner or cable like this and I know to not walk on it or roll over it with anything, so I have to assume shipping damage.

Anyone think I am on the right track here or is there something else I should be checking? I want to make sure the problem isn't on my end before going back to the manufacturer with this. Thanks in advance for the help.

Chris.

davedj1 · Mar 23, 2013

What type of metal were you welding both times? How thick and how hot were you welding? I'm no expert but I have noticed I get the same thing every now and then but only when I have the machine cranked right up and am doing some heavy welds. Do you have a purge mode? If you do, check to see that you have gas coming out.
Keep us posted.

Paul N · Mar 23, 2013

Could it be that the gas is leaking out through the damaged spot on the cable? If so, you could try taping it.

If your welding outside, it doesn't take much of a breeze to blow away your shielding gas. Or even indoors with the fan from a heater.

ChristianHF · Mar 23, 2013

The material was 16 gauge hot rolled mild steel, slightly rusty but clean on the cut edges which is what I was welding on. I tried varying the voltage from 17 to 18.5 volts all with the same result. (this was the suggested range on the miller weld calculator) I couldn't feel any gas coming out of the orifices, but 20 CF/hour isn't much flow and didn't think it would be something I could feel. Am I incorrect on this? The unit doesn't have a purge mode but I am willing to waste some wire and gas exploring this angle if it is believed this might be the issue. I was welding inside, near an open garage door, but there wasn't a breeze at all and no fan. Wire is ER70 S6 Sorry I forgot to include this originally.

ericher69 · Mar 23, 2013

You couldn't feel any gas can you hear any when you press the trigger? Turn the wire speed way down and hit the trigger while keeping the nozzle near your ear. You should feel and hear 20cfh.

How's the pressure on the tank/regulator?

Your reg/pressure gauge may be broken and the bottle is near empty??

Just trying to help

joshuabardwell · Mar 23, 2013

I don't MIG, so excuse me if this is dumb, but could you back the wire out of the liner and back onto the spool, then take the spool out of the welder and run tests on the gas without spitting wire and wasting it?

Mark @ Everlast · Mar 23, 2013

What machine is this. With the exact numbers you gave on voltage, it would appear to be an import machine? Is it an Everlast? If so, there are a couple of things I'd check. One, is to make sure I was using the right size drive roll. The other is that you might need to double check that the wire is riding IN the groove and not in between the grooves. And if it is our machine, the gas is in lpm not cfh.

Paul N · Mar 23, 2013

You should be able to hear and feel 20 cfh. That's the setting I use. To test flow on my welder, I release the pressure on the drive rolls so no wire comes out. Then pull the trigger and hold it up to your ear, then your lips (don"t touch your lips). If there's no flow at the nozzle, and the flow meter shows there is, then I would say you have a break in the line between the valve and the point of attachment to the cable. It could be a loose connection or a crack in the line. Either way, it doesn't sound too serious. Just take the side panel off and start snooping. One more thing. On my Miller, where the cable plugs into the machine, there are 2 O rings for the gas. Another simple and cheap fix.

ChristianHF · Mar 24, 2013

The bottle is about 1/2 full, reading about 900 psi on the gage. The flow meter is brand new and the gauge seems to function correctly and is in SCFH. I will take the flow meter off and crack the valve to check it out today. I will also check the flow with it connected if the pressure in the tank checks out. Thanks again.

Chris.

bikerdib · Mar 24, 2013

My vote it that the hose is damaged and either blocking flow or leaking. I agree with others, either release all tension on the drive roller or turn the wire speed all the way down and listen.

Arc weld · Mar 24, 2013

Esab makes a flow meter that goes on the nozzle to check gas flow at the arc but they cost about $30. There's a very slight possibility that the gas solenoid on the machine is malfunctioning and/or leaking. Being the liner was damaged, it sounds like the problem is in the gun cable. It would help to know what machine it is.

chub380 · Mar 24, 2013

What the others have said, you can for sure hear the gas at 20cfm ,could you ask your dealer to swap out your gun to check and see if that solves it, also check the connection at the machine may be leaking at the seal

ChristianHF · Mar 24, 2013

Ok, did some more testing a few hours ago. First I pulled the replacement liner and blew out the gun cable with compressed air, nothing came out, it was clean. I hooked the linerless gun cable to the machine, turned on the gas and checked for flow, it was good. Re-installed the liner, and the tip (no wire in the liner) checked for flow, good again. Fed the wire into the liner and figured I'd do a few test welds, here are the results.

A multi pass fillet weld done last weekend without porousity problems (yes I know its very ugly)

Single fillet weld done last weekend with out porousity (yes I know its very ugly)

Lap weld done today done a few hours ago, porousity at start (left side) smoothed out at the end.

fillet weld that started alright but got nasty for the remaining 2/3rds.

fillet weld, 2 starts, both started ok, then got nasty at the end.

Definately leaning towards the gun cable here, I did a leak down test on the hose and reg. Turned off the unit, without bleeding down the pressure and watched to see if it lost pressure over 15 minutes or so, no noticeable leaks (at least up to the machine solonoid.

For those that asked, I have not posted a machine brand because I dont want the manufacutrer to get a bad rap for a mistake I might be making. The machine is under warranty so I will take it up with them once I have a consensus that its not something I am doing wrong. Thanks again for the input and help.

Chris.

Chris.

chub380 · Mar 24, 2013

Something for sure is not right, it looks like you are running out of gas coverage You are sure the cable is hooked up right in the cabinet make sure its not set up for fc wire but if you have some fc wire try it that would eliminate if its the machine or not. Also grind your joints to a bright finish before trying to weld them. see if that helps .If its a hobart mabye some millers put the control on purge and try to see if the gas coming out is consistant; purge will not let wire feed, also make surre theres no oil or anythig like that around they area of the weld.

Mark @ Everlast · Mar 24, 2013

Honestly, I think it looks like you are varying your gun height, and angle and not readjusting as you travel (or readjusting to correct as the case may be). It's going to be one of the 2 oar 3 import brands here. It could be a cup size issue. All units have issues...but some have charachteristics that lend themselves to checking certain things before checking others. Without a knowledge of which brand it is, it is hard to say exactly.

The other main issue you have is the total lack of metal prep. Contaminated metal alone can cause porosity.

Scooby074 · Mar 24, 2013

It could be a pinched hose or some other gas flow problem, but I kinda agree with mark here that your joint is not prepped. Oil or other surface contaminants can cause porosity just like that.

Try it again with proper joint prep (a grinder is your friend) and see if your results improve.

ChristianHF · Mar 24, 2013

Ok, been testing for the better part of 2 hours and have found the problem. Let me start by saying I started out trying the same setup as described before but with metal ground clean and shiny and had the same result, randomly porous welds.

To back up a bit, this all started with a kinked liner. There was some impact on the hose, likely in shipping or assembly, that caused the original liner to be kinked and was causing random wire feed issues. Me being gung ho to continue my project I went to the LWS and purchased a Binzel liner because I had been told it was an equivalent to the Trafimet liner (not by the manufacturer of the unit btw, shame on me for not checking). The only place I could find Trafimet liners was on European web sites. Anyway, the Binzel liner was a drop in for the Trafimet with one distinct difference, the Trafimet liner has a heat shrink tubing of sorts from the wire feed end up to within a foot or so of the gun. And it dawned on me, that was likely to direct the gas up to the gun end and not let it seep between the liner coils and out the feed end of the gun cable.

So in with the old liner, and back to beautiful?!?! non pourous welds. Gas flow was much improved, I could feel it flowing when I tested before but it was now much greater now that the original (and correct) liner was back in.

Problem solved, I am an idiot

Chris.