Sometimes, the wire speed varies on my 175. I have checked everything, and
can't find anything wrong with it.
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.
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..
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
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
Sorry if I was technically incorrect.
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
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