Miller 252 Drive Roll question need help with parts

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Im having trouble with my drive system slipping on a 2.5yr old 252 and its not my liner or tip etc. Im thinking by drive rolls are worn out if thats possible????I looked on miller and they have two parts numbers for .035 hard wire regular wire no aluminum etc.The machine has a 204579 combo .030-.035 which I never use the .030.Miller has a KIT,DRIVE ROLL .035 V-GR 2 ROLL and a more expensive KIT,DRIVE ROLL .035 VK-GR 2 ROLL.Anyone know what this deal is between the two parts numbers. Is one a V groove and the other a U groove etc... Seems like U-groove is better than V but don't know if i even have the option.Anyone help me out...
Reply:The 'k' in 'VK' is for knurled.  It is designed for flux core.If you can find the u-groove rollers, that's typically for aluminum.I've never worn out a roller, but that's probably because I don't weld enough.1) Use Lincoln wire.  Seems to be pretty consistent thickness and easy enough to come by.2) Make sure wire comes off the spool cleanly - watch the overlap of wires.3) double check main spool tension - easy to over tighten that one.4) make sure everything lines up, rollers, wire liner etc. - a straight shot if you will.5) There is quite a range of tension adjustment.  The ideas is to use the minimum5) Do a reset on the machine - that machine has all kinds of adjustments for run-in, jog mode etc.  If you are not aware it can do funny things on wire speed.How did you determine it was slipping?  Wire against a board?Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Ok, did some research on my own off of millers site.The V-GR is a V-groove for regular hard wire.the VK-GR is a Knurled roll for Flux-core.And they also make a U-groove for Aluminum wire.I can see where the knurled roll type that has the teeth would have a tendancy of clogging up the liner more but im wondering how the V-groove could be better than the U-groove roll regardless if your running aluminum or regular steal wire?  Seems as if the U would be a better choice all the way around for traction on the wire. Im no expert and i guess i'll go back with what is supposed to go on but why the V groove on solid wire and not a U???
Reply:confuse9 you posted right before me, give me a second to answer...
Reply:Yeah.  I'm sure worn out drive rolls are your problem.If you've put a couple tons of wire thru them.Personally, I'd be looking for other causes of the problem.  I hear operator headspace and timing can be the most frequent culprit.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Ok to answer your questions.I use Lincoln L-56. Although im thinking about trying Inweld to save some money later down the road.Questions 2-6 have all been checked.And yes i do the test on the board. But mostly, when im working on a standard height table the welder has trouble pushing the wire up to the gun welding something on top of the table.The welder is say 2.5 yrs old and maybe has say 12 44# rolls of wire run through it to give an idea on its usage.
Reply:Not sure what it can be, liner is good, tip is new, wire is in good shape, I use the cloth wire cleaners etc.My airgas rep says they wear down and get new rolls. I like Sundown didn't even know they wore out so thats why im asking here, kind of a double check if you will...
Reply:If the felt wiper has a lubricant added to it, try welding with the wiper removed.Have you verified that the V-groove of the lower drive roll is lining up proper with the wire?  When you lower the upper pressure roller assembly are you verifying that the V-groove in the drive roll is meshing properly with the wire?You're feeding the wire to the drive roll assembly from the top of the roll, correct?ESAB Migmaster 250 Hobart Ironman 230Multimatic 215TWECO Fabricator 181i & 211iHH125EZ - nice little fluxcore only unitMaxstar 150 STH - very nice
Reply:have you pulled the liner out, i too thought i had a bad drive roll, and since it was saturday and all lws were closed i checked the liner to be sure.  lo and behold i had a kink at the base that was holding the wire back.  just asking.timJust some stuff in my shop.
Reply:Hello chadwickz71, you may wish to start off from the get-go and verify that each of your components is working as it should. First off, check the tension on the wire spool, an easy way is to just try to turn it and see that it doesn't require much more than a slight push from a finger. Spool tension should only be enough to not allow the spool to coast when you release the trigger. Next, remove the welding gun and release the tension from the drive rolls, then try to pull the wire out the front, this will test the spool tension and also check to see that the wire guide that is in front of the drive rolls isn't plugged or gunked up. Reinstall the gun assembly minus the contact tip, again try to pull the wire through, if it pulls out relatively smoothly you can probably rule out a liner problem. Install the contact tip and try this again, you shouldn't notice an appreciable amount of additional drag. If you do, it is likely that the contact tip is a problem. If all of these items, so far, haven't caused any noticeable amount of drag you are back to the feed rollers themselves. Have you visually inspected them to see if they appear to be worn or dirty? Many wires have a form of lubricant on them, generally it is there from the manufacturing process of the wire itself going through drawing to get it down to diameter. This lubricant can be caught and built up in or on all of the various parts of the feed system. If it gets on the surface of the rollers outside of the feed groove it can attract dirt and other debris and at some point it will actually contact the debris on the opposing roll and hold the two apart and not allow them to grip the wire properly. One of the other posters mentioned drive roll alignment. Definitely important, the screws in the center of the drive roll adapters have belville washers behind them, these act as springs and allow the tension of these screws to be adjusted and center the rollers relative to the wire feed path and also to one another. If these are out of alignment they will cause the wire to be sheared by the edges of the feed roller groove and shave wire shards that can plug things up. Inspect the inside surrounding area near and around the feed rollers to see if you can see any metal shavings or something like that. This could indicate an alignment issue. To check the alignment of the rolls, start out by releasing the upper roll and looking down at the wire, it's relationship to the rear wire guide and the entry to the gun assembly, if need be, loosen or tighten the center screw on the lower roll to bring it into alignment. Then carefully and slowly drop down the upper drive roller and see how it lines up with the lower one and the wire. The upper roll likely has a bit of side-to-side play due to the loose tolerances of it's design so it will probably find it's own center, but if you notice that it pops into place instead of smoothly locking down then it might require a similar alignment adjustment.      Finally, pay attention to how you lay out your welding whip when you go to weld, don't twist it or kink it unnecessarily. Sometimes that last one is overlooked as we are so involved in thinking that we have a mechanical issue with our feeding problems. Good luck and best regards, AllanLast edited by aevald; 11-16-2010 at 08:46 PM.aevald
Reply:thanks for all the info guys. Seems like I checked all of the above today.  Im gonna give it one more lookover tomorrow morning and then make my decision on what to do.I think if everything looks up to par im going to first remove one of the cloth cleaners as I have 2 back to back. The first one has the wire cleaner/lube on it. Im wondering if its causing more harm than good and actually either getting the drive rolls oily or causing more debris buildup than normal as one stated.Do you guys use the cleaner/lube on your wire cleaners anyways.
Reply:Been on the forum reading a bit, seems as if I probably need to stop adding the cleaner to the pads im using as the wire doesn't need it. Also seems as if one of the wire cleaners instead of two is better.i use the cylindrical pads with the spring type clamp on them that hold the pad firm on the wire.Is that even necessary...
Reply:Is their any way you can have someone weld while you observe the drive system in use.
Reply:Yes, eliminate the lube and cleaner pads.  You don't need them.  Just keep the feeder door closed to keep out dust and blow it out with air once in a while to keep it clean.Drive rolls do wear out, but it takes a lot of use to wear them.  I wore out a set of 4 u-groove drive rolls on the 350P I used to weld with at my old job.  This was a fast-paced high-volume production job.  I put at least 500 rolls of wire through the machine before I flipped the drive rolls to the fresh side.  I was having some feed problems with it, tried every thing I could imagine to solve the problem, even sent it out for factory tech inspection twice, and the thing that finally fixed the problem was simply flipping the rolls to the fresh side  (both grooves were .035).  I felt pretty dumb for not trying that in the first place...MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op