Feed problems

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I am very new to Welding in general.  I would also like to appoligize if I don't give enough information I just dont' have much experience.  Well I own a Cornwell Tools Mig which I believe to be a Miller (it is miller blue and was told by Conwell that miller makes it for them)  I purchased the Mig used, the problem I am having every time I've used it is that I don't think the wire is feeding properly.  It gets stuck every once in awhile (pretty often).  I use pliers and pull on the wire and it will feed again for another couple feet then gets stuck doesn't matter if I'm welding or just feeding.  I have always made a special point not to bend line shaply however as this is used I'm not sure if previous owner did that or not.  I have tried adjusting the feed tension and anything else I could find to adjust or that could contribute with no luck.  Is it just the liner?  Is there anything I can do short of buying a new gun/liner.  I am not familure and don't want to spend $100+ to resolve the problem but if that is what needs to be done I guess it is better then having a useless Mig. Please give me any tips and advice
Reply:Are you using flux core or solid with gas? What sized wire?
Reply:Flux core and I believe it is  30 not 35  Also since you have the quick replys I just remembered another qustion.  I am going to be helping a friend make some headers for a car out of stainless.  I don't have gas bottle and gauges for my mig is it ok to just make tacks with out shielding gas and then when we are done take it to someone to finish up the welds?
Reply:Flux seems to be prone to feed problems for beginners. I doubt you need a new liner. Since it's new to you, you might take the gun and cable out, take the liner out and blow it all out and start fresh. Couple of things, make sure you're running the right grove on the drive roller, check the tip for burrs inside and at the lip of the tip. The tips tend to get little burrs which cause extra drag on the wire. Get a new tip maybe. Even oversized won't hurt for awhile till you get the hang of it. They are cheap. Once you've slipped the wire you've scarfed a spot down at the drive roll. Stick it again and there's another scarf. So even when you've got it cleared and running there is a scarfed up spot heading towards the tip. Drive roll pressure just enough to give a good feed but no more. Too much pressure and you'll egg the wire.As to the spot weld with flux, depends on how important cosmetics are. If they are real important I wouldn't. You could easily contaminate the stainless at those spots. You'll get a good spanking from the shop you take it to.Someone that knows more and cares more about exhaust than I do better chime in on that one.
Reply:I have changed the Tip  didn't seem to help any.  The wire is getting stuck good enough I have to pull pretty hard to get it out with the pliers.  I think I will hook the machine up tomorrow with nothing around to weld on so I'm not tempted and just play with settings and maybe take it apart.   As for the exhaust I was planning on not using flux but using stainless wire like I would if I had shielding gas and just make say 2 tacs per cut area on the headers so it will keep shape until I can take it to someone who can do a nice job of welding it up as I understand I need correct pressure inside headers of argon mix so my weld lays flat on the inside as not to cause turbulance.
Reply:A couple very important things that are often overlooked when dealing with feeding problems is liner size and drive roll type. If the liner is too big for the wire used then it will start to bunch the wire inside the gun whip. If it is too small the wire gets hung up inside and will not allow good feeding. The fact that the wire was difficult to remove from the liner makes me instantly suspicious of the liner being dirty or too small. If you have any questions on correct replacement liners just take the welding gun into a welding supplier and they should be able to set you up without any trouble. Liners are cheap and you should have a couple on hand anyway. Also, when feeding flux cored wires  knurled Vee drive rolls should be used whenever possible. This will help grip the wire without having to put too much pressure on it at the drive casting. However, when welding with a solid copper coated wire, smooth Vee drive rolls should be used. If a knurled Vee is used it will cause the copper to flake off the wire and will eventually start to plug up the liner. As previously mentioned, you want just enough pressure on the drive rolls to grip the wire without causing the wire to slip, too much pressure will flatten the wire and cause even more feeding problems. You mentioned you changed the tip, be sure that your contact tips are the right size for the wire. Check the inlet and outlet guides at the drive casting. Make sure that they are installed and are the correct size, and that the wire is being held in the grooves of the drive rolls. I have seen times when wires were threaded poorly where the wire was not in the groove, but smashed between the smooth areas of the drive rolls. Keeping your gun whip as straight as possible goes without saying.Last edited by reddoggoose; 08-06-2007 at 01:48 PM.
Reply:If all of that doesn't seem to fix the problem, one thing to check for is ( I am not familiar with this welder) if the feed motor is loose. When I got my welder one of the feed motor screws was loose and the motor would just not feed. I took off the covers and saw the lose motor. Just something to check!
Reply:What you need to do when the wire is damaged as Sandy mentioned is remove contact tip and let wire feeed and when you feel the bad spot cut and then reinstall contact tip, usually my experience with this problem is drive wheel tension.AWS CWI Hypertherm 850 plasmaLincoln LN-25Lincoln SAE 400Miller Big 40D28' X 36' X 14' Shop_____________________________________Tools are not the the skill but simply tools!