Drive Rolls V-Knurled vs. U-Groved

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So this is basically what I came to understand as far as matching drive rolls with wire.V-Groved rolls are for hard wire.U-Groved rolls are for soft and soft shelled corded wires.U-Cogged rolls are for extremely soft shelled (usually hard surfacing types). V-Knurled rolls are for hard shelled corded wires.Now my question is when I bought my suitcase x-treme 12vs with the dura-flux it came with V-Knurled drive rolls for self shielded flux-cored welding now if I want to weld with a regular flux-cored wire out of my q-gun should I buy the U-Groved drive rolls or will I be able to weld just as well with the V-Knurled rolls? Also the V-Knurled drive rolls that came with the feeder are for .068, 0.72 and 5/64 wires and the regular flux-cored wire I have is .035 so ultimately i'll have to buy either a new set of V-Knurled or U-Groved drive rolls, I suppose I'm supposed to go with the U-Groved? Are self shielded flux-cored wire that much harder than regular flux-cored wire?Also what I don't understand is if V-Knurled drive rolls are supposed to be for hard shelled corded wires than why does the Miller Spoolmatic 30A Spoolgun use them for aluminum?
Reply:Knurled will plug your liner faster.
Reply:Originally Posted by Fat BastardKnurled will plug your liner faster.
Reply:I think what FB means is that knurled rollers leave teeth marks in the wire and little pieces of this chewed material come off when travelling through the line and... so you get an accumulation of metal particles in your liner.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:Originally Posted by Rick VI think what FB means is that knurled rollers leave teeth marks in the wire and little pieces of this chewed material come off when travelling through the line and... so you get an accumulation of metal particles in your liner.
Reply:So as far as regular flux-cored wire is concerned the U-Groved seems like it would be the best bet, I assume than V-Knurled is specifically suited for self sheilded flux-cored wire? Or do people use U-Groved for both self sheilded a regular flux-cored wire? What provides the best results?
Reply:I suppose the quality of the drive system and gun may play a role but I've got two different machines and I just run whatever standard rollers that come with the machine. I've ordered rollers but never asked for any special style. Whatever is standard that's what I run and get by fine. Not syaing I've never had problems, oh boy I have, but I've yet had a serious issue that when it was all said and done I could blame specifically on the rollers or couldn't be solved through proper set-up or technique. Maybe when I get so dayem good I can feel a fly land on the wire while it runnin then I'll start fine tuning the drive rollers. "The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Originally Posted by Sandy...Maybe when I get so dayem good I can feel a fly land on the wire while it runnin then I'll start fine tuning the drive rollers.
Reply:KNurled rollers in a spool gun are an entirely different thing, as the wire doesn't have to go 15 feet through a liner after it leaves the roller. Not sure what a U cogged roller is, never heard of it before. I run plain u groove rollers in all my machines, though I mostly run hard wire. When I do the occasional cored wire job I don't switch rollers and they seem to work just fine.
Reply:I use V groove knurled rollers for all cored wires.  If you use smooth drive rolls with cored wire, you may have to turn the drive roller pressure up high enough that you squash the wire(which lets the magic inside leak out).  Losing the flux or powder inside of a cored wire ruins your weld metal properties and gums up the gun liner that much faster.The amount of drive roller pressure needed is a function of how long a gun you're using, how many sharp bends are in the gun, how stiff the wire is, how good a fit there is between the liner ID and the wire OD, etc.  So, you may be able to run a cored wire with smooth rolls at one point, but then have problems with feeding later on.Yes, the knurled drive rolls can produce shavings that will plug up a gun liner.  But gun liners are a Consumable item.  They wear out due to grooving on the ID of the liner no matter what kind of wire you're welding with.  They also plug up with the lube that's on the wires' surface. They pick up contamination from grit that sticks to the wire you left on the machine overnight or while someone was spraying your spool of wire with grinding dust. So you should be replacing them on a regular basis, regardless.  Unless you like fighting with wire feed issues.  How often you replace them depends on the wire you use and how much you use.  Solid wires run on smooth rolls don't suffer from being squashed by excessive drive roll pressure.  But they still will birdnest if you turn the drive roll pressure up to high to compensate for a choked gun liner.  Most of the same things that deteriorate a liner used with FCAW wire are still a problem with solid wire.  So the same rule applies.Smooth U-groove drive rolls are usually for aluminum wire.  Even though the aluminum wire is solid, they are soft enough that they can be crushed or scored by a smooth V-groove drive roll.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:From a Miller literature;"V" groove for hard wire"U" groove for soft wire or soft shelled cored wires"V" knurled for hard shelled cored wires"U" cogged for extremely soft wire or soft shelled cored wires (i.e., hard facing types)That is on paper. When talking to Miller, they told me;"V" groove solid steel mig wire"U" groove alum wire"V" knurled flux cored steel wire"U" cogged hard facingPretty much the same but spelled it out. I only have "V" groove and "V" knurled."Where's Stick man????????" - 7A749"SHHHHHH!! I sent him over to snag that MIC-4 while tbone wasn't looking!" - duaneb55"I have bought a few of Tbone's things unlike Stick-Man who helps himself" - TozziWelding"Stick-man"
Reply:Ran into this issue yesterday. A less experienced welder at work put a smooth roller on for dual shield and coulnd't figure out why the wire was sporatically "jumpy", I switched him to the knurled rollers and problem solved. BTW, if you start getting shiny spots on the flat spaces between the grooves, the drive roll is worn out.Millermatic 200Hobart Handler 120Victor O/A & Ramco BandsawLincoln 225 ACSnapOn AD HoodMiller XMT304/22AHypertherm Powermax 1650 G3Lincoln Idealarc DC600 w/Extreme 12 VSMiller Digital Elite "Joker"
Reply:Originally Posted by RaptorDuner BTW, if you start getting shiny spots on the flat spaces between the grooves, the drive roll is worn out.
Reply:Can't say whether it was any cause to this welder's issue, but replacement of the smooth roller in my Lincoln with the $20 knurled version, together with a bunch of other fixes, has resulted in a very smooth unrelenting delivery of wire through the contact tip. I'd think they'd mak'em that way for a reason.XMT304 (school)SP125+ (home)HF 4x6 BandsawGood judgement comes from experience and much of that comes from bad judgement.
Reply:Originally Posted by Stick-manI would think you just need to adjust your alignment.
Reply:Originally Posted by RaptorDunerNaw, I've wore out two sets in 3 years. The knurling wears down and the rolls start touching each other causing the shiny spots.