MM 350P problems

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I have been having a problem with my 350P for the last 3 months and all the people that look at it can not figure out the problem. I welds perfestly with the 15ft gun (bernard Q300) with 035 and 045 wire. I change it to the 20ft gun and it welds like ****! wont work with 035 or 045 wire in the 20ft gun (bernard Q300). It weld totally different between the 20ft gun and 15ft gun (even with same settings and same wire). Bernard sent me several Liners to replace because I thought the first liner was 1/4" short so the sent me replacement to try. That did not solve the problem. I replaced all consumbles to that gun, even switched the two gun tips, diffuser to make sure it wasent that.Ok the 15 gun welds perfect with no "hanging" in the wire or "poping" and has NO spatter on the weld bead.the 20ft gun has several "pops" while welding as if the wire was hanging. The welds has an unacptable amount of spatter and has a very rough start. the wire will almost burn back to the contact tip.I have tried different gases, brands of wire, different settings, and just about everything I could think of. Anyone else have any ideas on why it just wont weld with teh 20ft gun.PS it makes no matter in the welding or bead appearance if I have the gun and liner straight, or coiled. it still welds like ****.I have pics that I can post up but Ill need to find them.
Reply:ok here some picsthis first pic was weld with 15 ft gun. I forgot the settings but the are the reccomended setting on the front of the welder. It looks a little cold to me but it still looks ok to me.the second pic is same wire, settings, ect. but just with the 20 ft gun.it parent metal was hot from running several beads on the back side so it looks like it had more volts on that weld, but it was the same settings. you can see at the right side of the photo, the welds starts looking better and it will look ok for a while and then the arc messes up again, and it looks like the start of pic # 2. Attached Images
Reply:As I remember it, when I got my 350P, I read on the package the gun came in, as well as in the machine's owner's manual, that changing the gun length, or basicaly anything about the gun that might make wire feeding different, would cause the machine to weld differently and possibly not up to expectations.   Makes sense.   You're trying to push a longer rope down the gun, it doesn't surprise me it gets a little skwerly at times.   On the 25' Python push-pull guns we used to weld with on the 350P's we had at work, the wire would sometimes go fast and slow like that.   There really wasn't a fix for it.  We tried just about everything too.  It was just a really looooong torch lead to feed the skinny, soft .035" 4043 aluminum wire down.   Our old torches were the older Cobra push-pulls, basicaly same thing, but we had much shorter 10' and 15'  leads on them.  They fed the wire at a little more consistent speed, when they were working right.  I think it's just the nature of the beast, you got a long hose and the wire wants to do what it wants, when it has to go that extra distance.   Might be why Miller only specs the 15' torches only on the 4-roll feeders and doesn't put 20 footers on anything, they know how long snakes get wiggly.Maybe try increasing the drive roll tensions a little and decreasing the spool axle tension a little and see if it feeds a little better, or, I guess you can try re-setting the feed motor torque, maybe that might help.  The instructions for motor torque calibration are in the manual.  In pulse, setting the arc length a little shorter might help compensate for it a small amount, although the feeding problem will still be there.Last edited by DesertRider33; 04-24-2008 at 02:54 AM.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Same as Desert Ridder your trying to push a wet noodle beyond the distance it can be pushed.
Reply:Your setting may have to be a slight bit higher with the longer gun also because you may be getting a slight voltage loss due to increased resistance. But i doubt this is the source of the problem. As stated increase drive roll tension slightly. Also make sure that your gun is laying pretty flat and strait with minimal loops or anything. --Gol'
Reply:Ok I contacted Miller and Bernard before I got the 20ft gun and they said it will push the wire with no problem, they both even said that the 4 drive rollers can push the wire 25' with NO problems. Miller told me the only reasons that they dont reccomend a different gun is because people want to go with a smaller size gun and it cant carry the electrical current, the it add restence in pulse mode; which could melt the copper cable in the gun. (a bigger gun is ok and they said the Q300 in a longer length is ok If I dont run it at max).The hub tension is only finger tight.The drive roll tension is set correctly, but I did try running it tighter. Thats not the problem (the wire is not slipping).I tried different arc lengthsd and more induntence. I did reset the drive motor per owners manuel.So it sounds like the cable maybe too long.
Reply:O ya, for some reason it seems to work OK in pulse mode with the 20' gun. It still is not as good as the 15' gun though. Most of the problems in in mig mode. I did also try to turn in the voltage a little to conpensate for voltage drop.Here is what I think is happening. I am running the 035-045 liner in the gun. the liner is actually size .054 to allow the wire to flow smoothly. I thin there is just enough room for the wire to be flowing through there and then hesitate causing the wire to "S" or snake inside the liner which causes slight hesitation. that may just be enough for the excess spatter. Could that be possible.
Reply:It is plausible.   Try an .030 liner with .035 wire and see if it helps.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Ace,I would be interested in what you find, I run a 20' Tweco #2 gun running .035" ,  a 25' Tweco #4 gun running .045", , and have also ran a 20' Tweco mini-mig running .023" wire with no problems.Jack
Reply:Brian here are the pics I was telling you about.I try a few different thing and see it that helps. I take more pics of my results today and post them.
Reply:Originally Posted by ace4059Here is what I think is happening. I am running the 035-045 liner in the gun. the liner is actually size .054 to allow the wire to flow smoothly. I thin there is just enough room for the wire to be flowing through there and then hesitate causing the wire to "S" or snake inside the liner which causes slight hesitation. that may just be enough for the excess spatter. Could that be possible.
Reply:I did not take any pics. I welded some 3/16" coupons. I played around and found a sweet spot at 18.2 volts 272 ipm  and 18.9 volts 310 ipm (.035). Both guns layed good beads and the beads looked exactly the same (looked like pic # 1) very little spatter. The 20' gun did have a few burps but did not create any more spatter that the 15' gun feeding smoothly. almost spatter free welds.It is frustrating that is a on and off type of a problem. But I could still tell a difference between the 15' and 20' gun on how it welds.I am using a precision wound spool of wire but while feeding out the wire I could see where the wire was almost catching and that might add to the formula causing the 20' not to work as well. The 20' also would run 045 better at first but now there is no noticeable difference.When I received the 20' gun it would not even run a decent bead. After replacing the factory liner that was cut too short it ran ok.My conclusion. the 20' gun works and it works ok, but not perfect. The 15' gun runs an excellent bead with any wire and I have not problems with it at all.I still dont know what would be the cause of these problems but I think it could be several very small issues but all added together they are causing the problems. I ran 3 different rolls of wire though (maybe 5- 10 lbs of each roll) it of 030, 035, and 045 wire and that did not make much of a difference.I read in somewhere where a welding company (I think it was Hobart) and they said it takes 100% more force to push wire through a 12.5' gun than just a 10' gun. Now thats a lot more force for 2.5' I have talked to several people and they run 20' and 25' guns with no problems, but this machine wont do it to my liking. Maybe I am just too picky and dont want to waste time with post weld clean up. It could be I might have a bad motor on the drive rolls and they suffer from the 20' gun but I guess if they go out then Ill know. There is just too many variables to know. anyways I am most happy with the 15' gun so Ill just keep it, and send the 20' gun back. Thanks to everyone that has offered advice and for their time. Have a good Day,Ryan
Reply:A Miller tech called me and he said that the drive rolls are most likely slipping. He said use V groove rollers (which is what came with the machine). I was welding the other day, and come to find out, the drive rollers ARE slipping. I tried to tighten down the rollers and they still slip. It will not pass the block test with 045 wire. It slips more with 045 wire than the 035. I am using the 15' gun. I tried to crank down the rollers to level 5 for a few minutes and did the block test but they still slip. My other machines if I did that would birds nest or break the wire.Also the spool tension is set very loose. 1-2 on the settings will not even feed wire. 3 feeds the wire but any resistance it encounters it slips (this is where I had it set the entire time, I did the wood block test for the 035 and it passed but once I switched to 045 with this it failed on this setting). Even tried 4-5 and still slips.Any Ideas to help stop the drive rollers from slipping?