Ranger 250 / LN25 problems.......Help

[Meach]

I have a ranger 250 with an LN25 wire feeder (Guess I didnt need to repeat that huh?)
The problem is I am welding 1 7/8 OD x .065 Round Galvanized (Although it happened when I was welding bare 1/8" flat also) 20 volts 275 IPM .035 wire C25 gas
The arc burns up the wire so I have about 3/8 of an inch gap then it goes back to normal.
This happens about 3-4 seconds after initail arc is established. Good for 3-4 secons then it cycles back and forth. Of course I checked drive roller condition and tension. Checked to be sure the roll of wire was not tight and didnt have any crossing wire etc. Changed tips,
nozzle, roll of wire. I watched the roll of wire while someone else welded and the wire
"appears" to be feeding smoothly, couldnt see any variation in spool speed. Now I do have a 45 liner in the Magnum 300 mig gun but I always have had and this problem just started.
What about the work connection? My clamp doesnt fit over the 1 7/8 tube so I cut a small slice of the pipe and welded it to a vice grip type clamp so it would stay well on the round pipe and I connect my work clamp to the clamp on the pipe. Would a poor ground cause this problem though? I hope its something simple I'm not getting.

Thanks in advance,

Mark

[DetailerDave]

Check the teeth on the drive rolls. I have found that you can get a build-up of junk at the root of the teeth. This could hold the drive rolls apart, and you wouldn't notice. Try putting your hand on the roll of wire while someone else runs it. You may feel a speed change or slippage.

[Meach]

Check the teeth on the drive rolls. I have found that you can get a build-up of junk at the root of the teeth. This could hold the drive rolls apart, and you wouldn't notice. Try putting your hand on the roll of wire while someone else runs it. You may feel a speed change or slippage.

I cleaned the drive roller real well. When it is running you cant stop the roll with your hand there is no slippage there at all. Good thought though thanks

[ventureline]

Does the top idler roller in the feeder happen to have a groove in it......... If it does then it's worn out. the wheel is merely a #6202 bearing and can be replaced as such.

Just shave off the nubs on both sides of the holder, pry off the bearing assembly, remove the 2 round locks, remove the offending bearing, replace it with a better quality unit, reassemble and tack the holder back together. This will save you around $40 bucks on a new assembly. LN7/ LN8 or 9 GMA units are the same as well.

[lars66]

I cleaned the drive roller real well. When it is running you cant stop the roll with your hand there is no slippage there at all. Good thought though thanks

do you have the drive rolls to tight? that will crush fux core & the feeder works erratic with solid or flux core.

[Meach]

I got it fixed. It was the work connection. I welded a short piece of 1" EMT to my vice grip type clamp that I had modified to work on the 1 7/8 round tube, cleaned it all up and the problem vanished! Originally I was attaching my work clamp to the handles of the clamp I had on the tubing, I ASSUMED (need I say more) that you either had ground or didnt in other words as long as it was welding you had a ground. WRONG Everytime you think you have a good handle on what you are doing something happens to knock you down a peg. Keeps me humble. Thanks for all the help - Mark