Lincoln 175SP+ Question

Sometimes, the wire speed varies on my 175. I have checked everything, and
can't find anything wrong with it.
Questions:
How tight should the wing nut be that holds down the drive roller? Right
now, I have it pretty tight.
I just have the wing nut on the spool very light. Is there much need to
tension it at all?
Do these have liners, or do you have to replace the entire gun?
Would soaking in acetone do the liner any good? Is there a better soak?
The variance in speed usually happens at high temp settings using .030 wire.
I have a new contact tip.
TIA
Steve
Reply to
SteveB
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There's a lot of things that can go wrong with a MIG, you could start a mighty thread here listing them all..
I always set the drive rollers a bit tighter than they need be, but not much. The resistance to wire feed changes as you move and bend the whip more or less, but you don't want the rollers so tight that they can't slip when the wire sticks to the tip.
Describe the speed variation you're seeing- speeding up, slowing?
Do you have something affecting the line voltage? Say, a compressor kicking on or off when the problem occurs? Adequate wire coming to the machine to handle the load? This is the first thing I think of when I hear of a problem only happening at a high setting, but it's certainly not the only thing that could be wrong..
John
John
Reply to
JohnM
Maybe a drop in line voltage or your gun cable has too many turns or coils. Make sure the wire spool isnt too tight. Keep it just tight enough to prevent it from bird nesting.
John
Reply to
John
"JohnM" wrote
The power supply panel has nothing else on it. What happens is like the speed slows down, and the wire melts back, forming a ball instead of the ideal spray type of transfer. It is just like when you have the speed set too slow. Then I stop, and move the head a bit, and restart, and all is fine.
Steve
Reply to
SteveB
solid spray transfer with a 175?? that would seem to be an intermitent affair, at best. maybe the groove in your guide roller is worn/incorrect
Reply to
dogalone
Machine is almost new, and roller good.
What I was trying to describe by "spray transfer" is the steady "frying bacon" sound when it is working right, and the steady depositing of metal versus the "splut splut" sound and the molten BB growing on the end of the wire stickout.
Sorry if I was technically incorrect.
Steve
Reply to
SteveB
That's a good place to start looking. When you say "move the head a bit.. and all is fine", are you feeling/hearing anything like the wire jumping a bit? If so, the wire is hanging in the tip or liner, probably the tip. Don't count on a tip to be good, even though it's new- every tip is different, and some will last a long time while others just won't. Ever feel or hear a sort of buzzing when the wire is running? That's also a sign of a feed problem, the wire hanging and not running smooth. Hold the whip up, squeeze the trigger for a bit and watch the wire- it should come out perfectly smooth, if it vibrates at all then there's a problem somewhere, again probably the tip.
Oily wire will run poorly, as will rusty wire (the tiniest bit of rust can cause trouble at the rollers and in the liner) or wire with any dust on it. I don't know if the problem still exists, but some years back copper clad wire would sometimes shuck flakes of the copper in the liner and cause feed problems. Also, once in a while you'll get a roll of wire that's twisted. That'll give you all kinds of problems; screwy feed, wire jumping around as you're welding, etc. If you have noticed the end of the wire jumping to the side as you weld, that's probably the issue there. Sometimes you'll see it once or twice on a roll, sometims often enough to warrant a new roll. If you lost a bunch of turns of wire off the side of the roll and wound them back by rolling it, you'll have twisted wire.
Re; the power supply- you don't have to have anything else directly connected to the line that's serving your welder to have a voltage fluctuation issue.. Anything that draws enough will drop the voltage throughout the system, but that's probably not the problem or you'd likely have noticed it and made the connection between cause and effect.
Try to reproduce the problem. If you can get it to happen on demand then you're at least halfway there. I'm not at all familier with your machine, and it may be something unique to it, but migs all have typical issues and if you can nail it down enough somebody here is going to know the answer.
John
Reply to
JohnM

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