Duty cycle intruding?

Hi all,
I'm a beginning welder that bought a Lincoln 135Sp+ about two weeks ago.
This evening I was
welding two .125" mild steel pieces together using a butt joint and after a
couple of inches my ability to lay down a good bead seemed to deteriorate.
I got stubbing and whiskers with little penetration. I don't think I was
changing anything (angles, proximity, stickout) during the weld. I've got a
fresh tank of gas operating at the called for pressure (20lbs).
I was wondering if I was running into a duty cycle problem. I realize that
at almost maximum voltage and amperage that I'm more likely to bump up
against this, but I'm not sure what happens when the duty cycle boundaries
are exceeded. How long can I weld until I have to put the gun down and let
everything cool down? What happens when the duty cycle is exceeded -
component overheating, internal CB or fuse tripped? Or does it change how
well the welder performs?
If this isn't it (and believe me, I'm perfectly willing to accept operator
error as the cause), any suggestions as to what I may be doing to change
the performance mid-weld?
Thanks,
Peter
Reply to
Peter Grey
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Could be a bad ground connection. Make sure you have the clamp on clean metal so you get a good connection. Also, make sure the wire is firmly connected inside the unit and that the wire is firmly connected to the clamp.
It could also be a wire feed problem.
Actually it's 20 cubic feet per hour rather than pounds. You're setting the *flow* of gas instead of the pressure. If you're welding outside and/or there is a breeze you'll need to up the flow some. This could also be your problem.
I can't remember for sure how the Lincoln is setup for duty cycle limit because I've never hit it on mine but I believe it stops welding completely while the fan stays on to cool the unit back down.
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"I'm not grown up enough to be so old!"
Reply to
Keith Marshall
First of all, thanks for your response.
I thought about this and ended up clamping right to the piece I was working on rather than the table. How would this change in the middle of a weld?
How so?
Whoops! I knew that... It was late and I was tired.
I was in my garage with the door open. I didn't think it was blowing hard (nothing notecable to me in the shop but then I wasn't trying to notice it either). Does it take much wind to cause a problem? Any rule of thumb for increments in which to bump up flow?
Thanks again,
Peter
Reply to
Peter Grey
First of all, thanks for your response.
I thought about this and ended up clamping right to the piece I was working on rather than the table. How would this change in the middle of a weld?
How so?
Whoops! I knew that... It was late and I was tired.
I was in my garage with the door open. I didn't think it was blowing hard (nothing noticeable to me in the shop but then I wasn't trying to notice it either). Does it take much wind to cause a problem? Any rule of thumb for increments in which to bump up flow?
Thanks again,
Peter
Reply to
Peter Grey
You're welcome. There are others that frequent this group that can give you much more informed advice than I can but since you have a new welder to play with I figured you would want whatever help you could get as quickly as possible. :-)
If you have a poor connection it will heat up because of resistance and the heat causes expansion which can cause the connection to get worse, etc.
It probably isn't if it's changing fairly consistently after so many seconds of welding but too little tension on the rollers can do strange things. Looking back at your original message though I see you mentioned stubbing and this usually wouldn't be caused by feed problems unless maybe your speed is too high. Here's a simple method of adjusting it that works well for me:
Set the welder up by the chart on the inside of the door and begin welding with one hand and use the other hand to adjust the wire speed knob. Find a point where you get the most consistent "frying bacon" sound and you should be good to go.
If there's any air movement at all I usually set mine at 25cfh. If it's a bit stronger and I really need to get a job done I'll go to 30cfh. Anything over that and I either move inside or put it off for another time when the air is more calm.
Did you buy the welder new and/or do you have the owner's manual? There should be a troubleshooting chart in it that may help. If you don't have it you can download it from the Lincoln site,
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One last thing I just thought of. Make sure you have the polarity set correctly for solid wire and that the connections are tight.
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"I'm not grown up enough to be so old!"
Reply to
Keith Marshall
I don't think you're having a problem with duty cycle. That machine uses a snap-action thermostat mounted on the diode heat-sink. The thermostat is connected in series with the trigger so when it opens all welding stops.
As others have already said, it sounds like you've got a bad connection in the welding circuit. In addition to checking the condition and connections of the cables, you may want to check for a loose crimp in the gun/cable assembly, especially if you purchased the machine used. One way to do this is to weld until the problem occurs, then feel the cable for hot spots where the flexible portion connects to the ends. If you have a hot spot, you've probably got a bad cable.
Good Luck, Bob
Reply to
Bob
Thanks. I bought the machine new so I shouldn't be having a problem as I've been careful not to step on anything.... I'll check anyway though.
Peter
connections
deteriorate.
Reply to
Peter Grey
make sure the metal is clean, no paint, oil, grease, shielding gas is not getting blown away
also an other thing ...... i noticed this when recently welded , some times I use a large strong magnet to hold metal pieces together, the magnets were not your average welding style magnets.
square and extremely strong.
when I weld near it , the matal is not getting deposited in a normal fashion. i guess because magnet and metal , molten or not are very good friends :-)
Reply to
acrobat-ants
I was using a strong magnet as a partial way of holding the two piece in alignment. I'll have to go back and see if the areas where the magnet was holding the work are the areas of problem. I don't think so.
FWIW, I tried increasing the gas flow and making sure my ground clamp was secured properly and the problem is better.
I do seem to do a better job when joining two pieces that are end to end and flat than when welding two pieces at right angles. Practice, practice, practice...
Peter
Reply to
Peter Grey
Thanks Keith,
I upped my gas flow to 25 and made doubly sure that my ground connection was good. That seemed to have licked it for the moment. Now my welds just look merely terrible instead of embarrassing enough to force me to grind them off and start over....
Peter
Reply to
Peter Grey
Been there, done that! :-D That's where the adjustment to wire speed that I mentioned in an earlier post helped me a lot. I've read that if you're using fluxcore wire the speed range that works well is fairly wide but with solid it's tight so it's important to get the speed set correctly.
I don't know about the fluxcore because I've only used solid but I do a lot better if I take a few seconds to adjust it for the smoothest arc. It also seems to be more critical with lower voltage settings for welding thinner metal.
What gas are you using? That can make a difference too. In most cases with mild steel a 75% argon / 25% CO2 mix is good.
If you mean welding in a V I've had that problem too. The arc wants to jump back and forth between the two pieces which is not helped by the fact that my hands aren't as steady as they used to be. :-)
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"I'm not grown up enough to be so old!"
Reply to
Keith Marshall
I need to try the "realtime adjustment" you suggested. That'll be interesting
That's what I'm using.
That may be it.
Some of my problem is that it's not always easy to see where I'm going. IOW, the joint isn't always visible. It may be that I need to go to a lighter shade of shield or light the work better. I'd assumed that the arc would provide enough illumination...
Peter
Reply to
Peter Grey
I have that problem too. I'm using an autodarkening helmet that can be adjusted from #9 to #13 and the #9 still didn't seem quite light enough for me. Putting a 500W halogen light over the work helps but so did adding a magnifier to my helmet. I've finally hit that age where my arms aren't quite long enough for reading any more so I use reading glasses and the magnifier helped a lot!
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"I'm not grown up enough to be so old!"
Reply to
Keith Marshall
Ha! I understand. I'm 47. My first project with the welder has been to modify the transmission mount on my car (I changed gearboxes and needed to change the mount obviously). At one point I'm under the car on my back looking up at the bottom of the car trying to read a machinist's ruler which I'm holding up to the transmission. I realize that in order to read the damn thing I'm going to have to jack up the car to get the ruler far enough away so that I can focus on it. Then I got a flashlight, slid off my creeper (giving me another couple of inches) and squinted and was just able to make the numbers out.
I'll try a lighter shield and break out the work lights.
Thanks,
Peter
Reply to
Peter Grey
Hmmm ... I doubt the magnet is affecting the molten metal as such; rather, it may be affecting the arc. As I understand it, this is what is known as arc blow? (I use an old AC stick machine, so I have not experienced arc blow even when using magnets.)
Reply to
Andy Wakefield
Oh, I have. I had a bunch of microwave magnets that I thought would be good to hold steel for welding. The first time that I tried it I got blow so bad that I never did it again.
I wonder if the kind (shape) of the magnet makes a difference.
Bob
Reply to
Bob Engelhardt
This is annoying. I bought these magnets specifically to hold parts for welding...
Peter
Reply to
Peter Grey
the idea is to use the magnet to hold the pieces till you put a spot weld on the joint.......... then rmove it.
Reply to
acrobat-ants
Greetings and Salutations...
I have too, actually...and it took a while for me to figure out what was happening. Part of the problem was that I had just picked up arc welding, and really did not know that much about it. I was trying to weld up a "t" shape for a chair support, and, had put a couple of largeish "arrowhead" magnets to hold the leg in place. As I tried tacking the leg to the top, near the magnets, the arc started bouncing all over the place and would not heat worth a nickle. Problem went away when I tacked it further away from the magnets. Just kind of wild to see, though. Regards Dave Mundt
Reply to
Dave Mundt
Got it. Thanks.
Peter
Reply to
Peter Grey

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