3G/4G Test part 2

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I though I'd take another shot at my 3G test this week. I put in a great deal more stick time in preparation for it. I get down to the school and the bottom falls out! I'd run a beautiful root for 1/2 the plate  and then start to loose it. The beads would start to sag and I'd struggle to get it to fuse to the edges. I'd stop and let it cool down then start again only to have almost no control over it. Pass after pass this happened ! I had 3 sets of test plates that I rejected because I knew they were questionable. I just couldn't figure it out.I had my rods in the oven for over three hrs. The plates were clean,clean,clean!. Clamped and tacked on the ends with an nice tight backer plate fit at the root. I was LOOSING MY MIND! I've been running beautiful joints at home why was I having trouble here? Could it be the machine? I ran my last sets that where sent out for x-ray on this machine. Its a Lincoln invetec V275 stick welder and should be up to the task. Before I rejected  the last set of plates I moved to another booth although having the same type machine.I finished up a fill pass with no problem but.. I started a cover pass with no issue and then is happened again! hard to get the arc started, it was as if the weld was going cold on me. So I cranked up the amps some more and it got better for a time but faded again. My instructor tried it and had the same results.OK, I've had enough of these inverter machines time to move over to the old relic of a Miller 250 in another booth.Another set of plates and another root pass but this time was different. I had control again! my restarts where almost invisible, smooth and flat. let it cool some and ran a hot fill pass. Again just smooth as silk. I finished this test plate with a real nice cap with only one spot that was a bit heavier than the rest. DONE ! my instructor took one look at it and said "Good to go out for testing.Nice job"Hey, that felt great! We talked about the days trouble with the other machines and decided some things.He believes the "hot start" circuit may have been fading. Even thought the machine could still weld it wasn't controlling the Dig as I but more and more time on it. He felt that's why the other machine finished the fill pass better. He mentioned that the reason I failed the first 3G test had to do with "poor or incomplete fusion" in the weld. I didn't notice it the first time because I was letting the machine cool more and running it on lower amps. This time I had more confidence and had the amps set higher and that may have been the tipping point for the machine. Well my test will go out for x-ray and I'll get back down to the school this week to take the 4G test WITH THE MILLER of course.has anyone here ever experienced anything like this? It's a lesson I won't soon forget!One Happy Gizzmo (Again!)
Reply:I usually roll my eyes when someone says it's the machine.But every now and then the machine does mess up. Glad you finally got it done.Lucky, that you get to run a few plates and pick the best one. I took a test at the school and they did it the same way. I took another test with the company. One and done. Little more stress but once you remember it's only a weld, and you know how to do it, it's easier. Good luck.
Reply:Did you put your practice time in on a transformer machine? I'd bet you did It's more likely that you weld better with old style than two inverter machines both not working right.I only guess this because it's true for me - I could be wrong about your experiences.I now understand the different techniques needed for each type, but my first time with an inverter was a terrible experience.This is what I'm talking about:http://www.millerwelds.com/resources...rticle108.htmlLast edited by MinnesotaDave; 10-22-2013 at 11:44 PM.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I'll add one more thought to the mix. Almost every place I've ever gone, the kids like to F with one another. It's especially easy to do this with inverters, either intentionally or not. Kids start pushing buttons and changing settings and new thing you know the machine isn't welding "right". I've seen them do it to screw with the kids in the next class for "fun" and I've seen them do this simply because they were bored and wanted to start pushing buttons.It's harder to do with "old school" machines though. Usually there isn't too much they can mess with taht isn't immediately obvious. but I wouldn't put it past them to find a way to do so.Good luck. I hope you pass..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by DSWI'll add one more thought to the mix. Almost every place I've ever gone, the kids like to F with one another. It's especially easy to do this with inverters, either intentionally or not. Kids start pushing buttons and changing settings and new thing you know the machine isn't welding "right". I've seen them do it to screw with the kids in the next class for "fun" and I've seen them do this simply because they were bored and wanted to start pushing buttons.It's harder to do with "old school" machines though. Usually there isn't too much they can mess with taht isn't immediately obvious. but I wouldn't put it past them to find a way to do so.Good luck. I hope you pass.
Reply:Originally Posted by MinnesotaDaveDid you put your practice time in on a transformer machine? I'd bet you did It's more likely that you weld better with old style than two inverter machines both not working right.I only guess this because it's true for me - I could be wrong about your experiences.I now understand the different techniques needed for each type, but my first time with an inverter was a terrible experience.This is what I'm talking about:http://www.millerwelds.com/resources...rticle108.html
Reply:Originally Posted by gizzmoI liked the link to the Miller article describing the differences between the machines,thanks. I read it several time to make sure I understood the material but cam away with some more questions. The biggest is- If the inverter machines maintain such an even current /voltage flow how does the welder cool the weld? With my transformer machine I can just shorten the arc length to cool things down but, as I understand it, the inverter type machine doesn't do this.Gizzmo
Reply:might want to take into consideration most companies will mess the machine up on purpose when you come in to test ...so it would be wise to learn how to set it upMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:Originally Posted by WookieWeldingmight want to take into consideration most companies will mess the machine up on purpose when you come in to test ...so it would be wise to learn how to set it up
Reply:Thanks for the replies and the encouragement. I ran about 20 practice welds before trying again. I'm more confident of this set of plates . The 3G came out much nicer than my 1st attempt.I also had the amps much higher that before. I went from 95 -100 amps on the inverter machine to 115 -120 amps this time.This should solve the "Incomplete Fusion" issue I had on my first 3G. Odd thing is, I seem to run everything hotter the more I weld. Maybe it's just the machine type, I don't know.I definitely like the transformer type machine better. I decided to make it easier on myself and ran all the 4G passes as stringers with a  weave cover pass.This eliminated may of the re-starts" in the middle of the plate as one rod would carry me from end to end. It was also easier to run it hot and tie in the edges better without leaving places for inclusions to occur. I also had better control over the final height of the fill pass resulting in a better looking cover weave.I did have a short section at the beginning of the weld where the cover pass was a bit heavier but the instructor decided it shouldn't be an issue. We'll see. As always thank for the instruction,suggestions, insight and time many of you have given to help me along. It's greatly appreciated .Gizzmo
Reply:Originally Posted by gizzmoOdd thing is, I seem to run everything hotter the more I weld. Maybe it's just the machine type, I don't know.
Reply:Good to hear it's coming together for you. I think your comment about running hot is pretty common - takes more experience to run hotter.  Which is good to a point.I did an experiment to see how hot I could run 7018 1/8" for vertical up on 3/8" plate with a backer. Rod angle 90 degrees.I topped out at about 135 amps or so. Over 140 and it was too fluid and nearly boiled the puddle.But I learned I can lay more metal in, with faster travel speeds, than I did with low amps.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:The hotter u can run your cap, the better it looks.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720