Notice MP350 Power Mig "Bugs"

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I have had an Pow'r MIG 350 MP with a Python (MK Products) gun for several years and found it to be a great power supply.   Now as with (nearly) all welders, I've sniveled that same amount of time about what seemed like Lincoln's "anti-one-man-shop" attitude in explaining the modes, weld arc characteristic settings and general support for the machine.But.... This post is about some real life physical defects in the system that may not be unique to mine, (?) and the cures which I hope anyone who experiences these 'bugs' will read and then employ to kill (exterminate) these 'bugs' .I have more than 5K hours looking at an aluminum arc so I'm this is not my first rodeo and when a wire feed surges, I know whether it's me or the machine. My system was not consistent on 0.035" aluminum wire.I'm addressing only smaller (0.035" ) wire and only aluminum and only on the power supply I have, I'm not bad mouthing Lincoln, except as above, and I hope no one else has these "bugs"- I hope they were unique to my system?First, the drive roll tensioning swing arm in my cabinet interfered and stopped the tensioning adjustment from working for smaller wires.Next, the wire conduit on the air cooled gun, not the water cooled model MK Python, had a defect that "schooled" me about small diameter feed in this system.Last, I found out the hard way that the MK isolated gun drive roll is a 'must have' part for aluminum wire welding, so if you have the vertically serrated steel wire drive wheel, (?) you may want to consider a parts order?(First) the internal drive rolls tensioning is done by a spring loaded gray plastic cylinder pushing down on the upper swing arm that carries the upper wire feed (follower) roller.  A spring is collapsed by turning a large nut on the shaft of a spring loaded swing arm.  More spring tension applies more pressure between the drive rolls and the wire is fed 'more positively'.  Naturally a finer, softer wire is fed with less pressure between these rollers so the 0.035" wire tension is the least setting on this spring loaded compression fixture.My unit was interfering at the cast fork just below the tensioning gray plastic adjuster where the upper arm overlaps the two upright 'ears' that hold the tensioner pivot.   My system snapped down instead of floating to be adjusted by the compression spring's pressure.There are a pair of arms that form a fork overlapping a female pair on the base roller and the tensioning spring assembly pushes down on those two fork prongs.  This is at the right side of the drive rolls assembly and mine were interfering so that tension adjustment was only effective at very high tension/pressure and the 0.035" aluminum wire setting was not functional.  This system worked decent in 0.045" (5356) wire and was great in steel or inner shield/dual shield but small alum. alloy wire fed poorly. What I had to do was to sand off the near side of the lower fixed padeye, or rounded pivot support, where it was too deep (that is the piece was too thick 'toward you' as you lift the cover) and the fork prong or overlapping padeye was rubbing inside - the symptom was snapping action when the drive roll upper swing arm was dropped in place to be tensioned. That arm should lay down smoothly over the two tension adjuster base 'ears' without touching them!!! Yours is probably fine but mine was not.Next, the air cooled Python, not the water cooled one, has a wire conduit and gas hose plug where the wire conduit is at the center. I found a very small defect in the inlet cone in the end of this plug that is mounted in the drive roll holder assembly to receive wire.  This tiny defect was a sharp edge that would 'skive' or shave a very fine strand of aluminum wire off the feeding wire and that shaving would form a bird's nest inside the wire conduit and eventually cause a surge in the smaller diameter wires after a roll or two.  I had to dress that conic orifice fitting at the machine cabinet end of the wire conduit to smooth it and that cured this tiny defect.  Now the same conduit is working well, and I'm not getting a balled up packing of shaved wire inside while welding. Sure did smooth the feed of 0.035" aluminum wire.I now make it a habit to use an air hose and blow out the wire conduit from cabinet to torch between each roll of wire. I'm planning to mount a wiper (lubricating fitting for steel wire) on the aluminum wire but leave it dry or perhaps add a drop of acetone periodically to reduce dust in the conduit.What is up?  Both motors are (apparently) effected by their relative amperage monitors, and the (wire) Stall Setting, so that if they see more drag (higher current draw) than the internal values set, the motors will slack off or reduce speed, slowing the wire, in order to keep from over driving the amperage. I don't know if this is factual, I'm just inferring from the machine's behavior, again the cryptic Lincoln literature is not much help!  (he sniveled)So if you pack the liner with some dust, and bits of shaved wire and set the Mode to a 0.035" wire mode (151, 152, 101), that tolerance for the motors amperage drops and the wire feed becomes erratic, making welding in smaller aluminum wire a pain in the stern.If you combined the cabinet drive roll tension being too high, and some junk in the wire conduit making the friction drag on the wire too high, the feed gets pretty poor! Move on to some thinner material where feed rate is critical??? things get messy and welds are not acceptable.With lots of sailor-like phrases about the Mothers of the Lincoln designers (all of whom are, I'm sure honorable and fine upstanding women of exemplary repute), I spent two full rolls of 0.035" wire looking for problems.Last, I experienced a groove cut in the drive roll in the Python gun after a few rolls of aluminum wire.  That is from "micro arcing" on the drive roll when the wire feed copper tip is not arcing as well as it should, the path of power is through the motor.  I ordered the aluminum drive rolls kit for both the 0.035" and 0.045" wire which is a nylon insulating thread sleeve for the motor's drive stud and an accompanying new drive roll with a wire sized annular groove in it instead of the vertically serrated steel wire drive roll that comes stock with the gun.Just a little heads up about this systems' idiosyncrasies, as they've shown up.  I hope these are non-issues for your system but please pass this along to anyone who has the MP350 system who might benefit?I still like the power supply, and would buy another one but if anyone experiences headaches with 0.035" aluminum wire, these are valid points to check as you trouble shoot.cheers,Kevin Morin
Reply:5356 AL is real bad to cause micro arcing. It can destroy a brand new drive roll with in minuets. It is the oxide coating on the wire that causes this. If your roll has been out of the package for a while it has oxidized. 4043 wire does not seem to have this problem as bad.MK has known about this for a long time. This is why the insulated wire size specific drive rolls were made. They have rolls for all their guns. The standard drive roll works with any size wire and gets you welding right away. some times they last a long time. when they ware out we change them to the insulated drive rolls. The stall factor is to keep the main drive motor from pushing the wire to fast for the gun motor and bunching the wire up. It is adjustable.Check under the pressure arm. Some of the early units had a bump of AL on the top of the drive that stopped the arm from coming all the way down. This caused feeding problems for all 0.035 wires. Just Take a cutting wheel and shave it down. This has been corrected on current units.Make sure you are using U groove drive rolls in the main drive. Any thing else will flatten the wire and cause feeding problems.
Reply:Can you post a picture of the bump that you shave off? We have two older 350mp's at school one was sent out for this exact problem It came back with new drive rolls and liner and was told they could find nothing wrong, It worked okay for a short time and started acting up again. if we leave the tensioner loose it slips if we tighten it up it starts to pinch and flatten the wire and then we get error code 81 or 82 both drive motor codes. Also id there a part # for the "fix" or do we just put a whole new drive assemble in?
Reply:I rechecked some information. If you have a pm 350 mp. the problem I described Is not yours.It was on the first generation pm 300 with the S24827 feed plate. drive assembly.If you have a max trax drive in your welder, yours is a totally different drive.The older drive at first had a bump of casting on the top under the pressure arm. we just cut them off. It kept the pressure from tightening up and allowed the wire to slip with the pressure turned all the way up. If you can crush the wire, you do not have this problem.Now, What wire and drive rolls are you using. Liner size and tip size.The error code 81 and 82 are both motor current to high codes. Any thing that causes the motor to draw to much current will cause this. Spindle brake set to high, drive roll pressure set to high, wrong or worn tip, Bad liner. knot in weld wire.If you are using flux core wire and hard wire (V groove) drive rolls. you can flatten the wire and cause it to bind in the liner and tip. V knurled are for flux core, U groove is ALMake sure the wire can be pulled off the reel and through the gun with little drag Pressure off.Start with light pressure and turn it up until you just get good feed with out slipping. should be able to feed against a wood block and turn a curly  wire with out slipping .V knurled rolls use light pressure. Post and picture of your drive and your code number and answer the other questions. Let me see what you are doing.
Reply:I will try and take a picture of the drive tomorrow. we are running E70S-6 .035 solid. It is a .045 liner with .035 tips the ones for the magnum gun a little bigger than what we run in the tweko guns. We have pulled several feet of wire with the drive open in both directions and could not get it to hang up. we cant seem to get it to curl the wire it either slips or as we add tension we get the fault codes. When you are running the bead you cant always feel the slipping drive rolls sometimes you can but you can hear the tone change and see the arc cone grow. We have tried it in program 10 as well, not as noticeable as program 14 but still not quite right. we do have the latest software installed. and have checked all the obvious culprits ground connections,new gas, which is 95/5 , brought in an electrician looking for dirty power. as well as waited till everyone went home to make sure we were the only machine running. I think that was most of the questions you asked about maybe one other observation sometimes when we release the tensioner the upper drive roll is still "locked down" and takes a little nudge to get it to open????? Had hoped it was a simple fix. Thanks for all your time sorry if this rambles on.....
Reply:gouch,ccaMy 350MP's upper arm would jamb/interfere/rub/restrict at the points shown and not act freely.I 'cut away' the ear, or padeye of the swing arms' right hand end to show the surface I sanded down.  The inteference was along this surface. If the swing arm is not completely free to move up and down, if it 'locks' down, or snaps down, it is not working correctly as near as I can see.This is a photo for the drawing above, and the interference is covered by the padeye or ear shown intact instead of cut away as in the sketch above.I found that 0.035" aluminum wire would feed much more reliably with the upper swing arm floating freely and being tensioned downward only by the spring inside the dialed compression screw above.Cheers,Kevin MorinLast edited by Kevin Morin; 03-04-2011 at 12:55 AM.Reason: forgot second pic
Reply:Kevin You need to have U groove drive rolls and the tension set almost off.The stall factor needs to be set right. hold the python trigger closed  and turn on the welder.The stall factor will come up on the display. Read your owners manual for the right number and get it set right. Your drive is the new maxtrax and no modifications were needed.The only weak point in that drive is not tightening up the large allen screw when changing the gun adapter. The Allen screw is part of a clamp that tightens the power block to the gun adapter. If left loose the drive will melt and the arc suffers.When using any pull gun with this drive lighter is better. The main drive only needs to push the wire into the conduit and keep up with the gun drive. The gun drive sets the wire weld speed. If the push drive tries to push faster than the pull drive can feed it, the motor should stall. If it pushes to hard the wire will accordion pleat and then it jams up in the tipAfter display read sf and a number between 5 and 35 release trigger set the number higher or lower , using   the volts knob. push select switch up to save any changes.Push drive pressure should be set between 0 and 2. Book says to  start at 1.5 .I just checked and all the book says about the stall factor number is to set it just high enough so the push motor has enough power to pull the wire off the roll and start it up the conduit. Look through the complete trouble shooting guide in the owners manual. There are some good tips on what to look for and how to set it.
Reply:Grouch95What drive rolls are you using? Make sure the gears are clean and not full of dirt.Check your spindle brake and make sure it is not set to tight. The wire tension between the reel and the drive should allow the wire to be tight when motor running and drop about 1/4 to 1/2 inch when motor stops. Make sure the wire is in the drive groove  and not riding between the grooves. If you know how to safely measure volts and amps on a working machine.Try to measure the motor current. It should be less than 3,5 amps. If motor runs at 3,5 amps for over 10 seconds it causes a error 82. See trouble shooting guide and error code chart for what causes error 81. Sense you know you have the latest software. you can get the power wave manager from the same web site. This will allow you to connect a computer and preform diagnostics. But to read the fault logs don't use the powerwave manager.after you have installed this package from Lincoln. Go to the Lincoln folder in the programs list. look for the legacy folder then more applications then the second diagnostics file and use that. It is the old program that has better features and allows you to save a copy of the fault logs before you clear them. Then you can compare a new set of fault conditions with the old ones with out having to write them down.You can also e-mail them. The snap shot files when made can only be read by sending then to Lincoln. You can send me a copy of the text files to me at yahoo and i will look at them. You have one of three problems, bad motor, bad pcb or something dragging the wire and causing high current. This is the most likely cause.
Reply:I believe the drive rolls are from Lincoln. I stopped by the LWS today and looked at the drive of a brand new machine and the first thing that i noticed is when the upper arm drops down it finds no resistance whatsoever. both machines at school when you bring the arm down you have to press it into place almost snaps in. I kooked at the wear marks on the pedestal that the tensioner is fastened to. and it looks like it not only needs to be thinner but that the bump to the outside is taller than the inside bump and shows signs of contact. My concern with shaving either the pedestal or the upper arm is maintaining a proper alignment with the drive rolls. Kevin thanks for posting the pics.
Reply:grouch95How old is your welder? post the first part of the serial number. The letter and the first 5 numbers. It will tell me when it was made. By drive roll type I meant  U  groove. V groove or V knurled and size wire.As a Lincoln repair shop I f the drive shows any problems of any type and it is under warranty it gets replaced. Problems like binding and extra loud gears or slipping.After the warranty's up then we try to fix them.  Some times if they are just out of warranty we can get just the parts under warranty from Lincoln.e-mail me on yahoo if you want to try some in depth trouble shooting on your motor problem
Reply:Kevin, I would not recommend a lube pad on aluminum wire, all manufacturers of aluminum wire will tell you that they apply a lubricant for feedability, and the pads can remove this lubricant. I've asked all of my solid wire reps as well, they don't even like them on solid wire. If you open up a used lube pad and see a graphite looking substance, that's wire lube, and it's not doing any good in the lube pad.
Reply:cc, ss, gouchthe drive rolls, as shown, (seem to have) had a frame or swing arm manufacturing error; the two ear's interfered and the swing arm tensioning mechanism did not work.  Past tense, it works well now that I've sanded the inner overlapping 'ear'.Once that ear was ground/sanded/reduced downward from the picture plane (pics shown) "way from the screen" then the swing arm (now) moves freely.  Formerly is 'snapped down' and only moved somewhat freely below the #2-3 on the tension screw. Now it works at the lower tension settings for smaller aluminum wire.I have the correct (new) 0.035" round groove drive rolls that are cleaned.  I have the tension set to "1" and the wire is feeding well, with a slight surge.  With 0.035" wire (5356) I have the wire roll spindle tension backed nearly off, and when the wire is stopped there is about 1-2 loose strands around the wire reel.   0.045" wire always fed well and was not a problem.The lube pad I'm (planning on) installing is not for lube of the wire, it is for dusting or wiping the wire to keep shop dust out of the wire conduit. If the wiper isn't dry and clean I won't use, but I will consider an acetone drip if I can find a drip valve and canister.I rigged this in Cobra's int he past, using an oil drip stove fuel valve and a small piece of carpet felt riveted to an aluminum arm inside the Cobra wire cabinet.  The reason was that the shop was dusty and the MK Cobra cabinet doors were not well sealed and we got dust in them all day.The cabinet end of the wire feed conduit (current 350MP) was found to have a sharp edge inside the small 'brass' cone that ended up cutting a bird's nest of shavings which rand into the conduit.  Now that the wire is feeding without shaving, I'm heading for the dust side of the equation, since there was a lot of dust in the wire conduit when it was cleaned.The reason the sanding or grinding I did to the interfering swing arm 'receiver' pad-eye can't affect the drive roll alignment is the hinge on the left side. This hinge/pin is through the entire swing arm casting, therefore the sign arm cannot move out of alignment.  I will check to see if that swing arm was mis-drilled/milled and the original interference was a result of that end of the drive roll upper swing arm instead of the lower right hand end of the lower drive roll frame.If that were the case then the wire drive rolls may be mis-aligned on top of one another and the wire may be pinched by two out of alignment grooves?The wire is held into the drive rolls by the paired plastic wire guides and they do seem to fill up with 'junk' more rapidly than I'd expect.  I have removed these plastic guides several times while welding with one roll of 0.035" wire and observed the grooves have a 'small lining of aluminum'.This plastic wire guide groove collecting junk is another reason I was going to install a wiper, not for lube, but just to get the wire surface rubbed clean of dust before entering the guides.However, now I will look closely at the two drive rolls alignment to see if the dust/junk is coming from the two drive rolls' grooves being out of plane and deforming the wire as they drive it?I think I'll leave out the plastic wire guides and check the face alignment of the two rolls when the guide is tensioned in the locked down position?  The drive rolls seem to mount positively, no movement, and they seem to align well but since I've not tested after the wire guides were removed, I can't really state their relationship with certainty.I don't show error codes, the wire only stalled once or twice a few years ago, I cranked the stall factor then, but I will recheck the stall factor, now.cc is there a table for stall factors and wire sizes or alloys?  gouch95; what you're describing (snapping down the swing arm) is exactly what I was reporting.  The swing arm, it appears to me, should have absolutely no contact with the two ears that is 'traps' when the drive rolls are in 'run' position.I think the hinge pin (at the left hand end) will take care of alignment, though, and see now side to side (in and out of the cabinet) movement of the drive rolls. More feedback/information when I get back to the power supply to take more informed observations.Thanks for all the ideas, background, facts and 'hardly known' realities about this power supply. I only use this (350MP) for aluminum with the (MK) Python and I have all the 'extra' parts that I know about, isolated drive roll kits, tip extender, long head liner, and I regularly use shop air to dust the drive roll assembly.cheers,Kevin Morin
Reply:ccawgc thanks for the information on the Stall Factor, I made a series of adjustments to this value, saved them, (ended up at 30 after working up 10, 15, 20, 25) and improved the 0.035" wire feed performance dramatically.Now the power supply is working flawlessly, and I feel as though I may be 'up to speed' on this great Lincoln product.I'll still need to install and use the water cooled Python to get reliable day-long welding, but I have that model gun and I'm building a tank and pump so I can cool the new torch.Thanks for taking time with this, Lincoln's network of products and people wins (for me) again.Cheers,Kevin Morin
Reply:You asked about a chart. I looked in the owners manual and the service manual.could not find a chart. What you did is basically what the manuals say to do.You might try calling Lincoln tech support or product support and ask if they have a chart.Procedure chart with wire size, machine set up with stall factor.
Reply:This is the drive I was talking about. See the round bump back near the hinge.It can not touch the lower casting at all. I think it was made as part of the casting process.One group of them did not get cut off right. The pictures are of a power mig 200.This one had a good 1/8 clearance and did not need any help. This model drive assembly is also known for breaking the drive shaft in the gear box. The good news is you can buy just the shaft and gear and replace it. easy repair. done several. Attached Images
Reply:Ccawgc,well I've added the MK drive rolls to isolate the wire in the gun's idler rolls and keep the micro arcing down to a minimum but I was still having wire to contact tip arc pitting and wire stalling.I called Lincoln's help line, and learned that MK has a 'spring loaded' contact tip for the Python using 5356 wire so I've ordered some.I adjusted the stall value upward, checked all the contact tips I could find to use for 0.035" 5356 wire, and was still having arc and burn back issues.I adjusted the burnback configuration value, crater fill feature, spot time, and tired different modes including 40, 101, 152 (or is that 151?) and I still fused the wire to the tip.Unfortunately it was only every three or five tacks, and didn't repeat but eventually happened over and over.  Lots of blue language and remarks about Lincoln or MK 's engineering staff's mothers.  Then, just a quick flip of the tip with a needle nose and the wire was free. But...the main feature of each freeze up was the huge arc pit exactly the length of the contact tip back from the end of the tip.  This implies the wire to tip arc was happening at the widest point of the tip, inside the inlet cone before the real 'bore' of the contact tip.  I found this odd, why would the arc happen over the larger gap than to just 'rub' along the inside of the bore.[Incidentally we cleaned these tips till they were out of spec, and we tried long ones short ones, other sized ones and even chased some odd threads on old 'King Cobra' tips of different bores.]This was a point of a large arc gouge in the wire, and a piont of fusion or at the very least a point where that alloy wire in the 0.045" bore (labeled for use with 0.035" wire) tip would arc to the wire.  We tried to vary each of the configurations, step at a time, in each mode, this took a work day and then some!  We tried to cancel all spot and burn-back and run on the trigger and we tried so many combinations I'm worn out thinking of the number of instances.When the new MK tips get here, I'll remark about the outcome.Thanks for bringing all your experience and expertise to the site and helping us learn to run this power supply with a push pull gun.Cheers,Kevin Morin
Reply:Kevin try calling MK and describe Whats happening with the gun and how it is weld and burning back to the tip. They make the gun for Lincoln So find out from them what it takes  to get it to weld right. Roger or Joey Might be able to point you at the right adjustment or gun setup. Just type in MK products in the Google search and their web site will pop up.
Reply:ccawgc,I called Lincoln's trouble shooting hotline/support phone service and got shuffled a bit until I finally talked with someone who knew the power supply and the MK/Python gun combination.He told me the MK had new tips out to address the wire pit/contact tip fusion issue. I ordered them, got them in and they are the ticket.  NO more sticking, tack all day using the spot function and enough BurnBack to pop the wire loose of the tack and the entire system is now working flawlessly.I have seen a few other shops have similar headaches to those we've discussed here, and the level of frustration was very high.  Now that I know these details, I am very pleased with the entire system's performance but I will note it was a long time coming.Now to get this boat built before my owner keel hauls me or uses me for crab bait!Thanks again, ccawgc, for all the help, references and guidance learning about this MIG system.
Reply:Sometimes when I call in you have to get real targeted in you questions and not take the first answer. But this goes for all the welder makers. Some tech support guys are better than others.