Welding Tips and Tricks

I have an old miller bobcat 225G (99 model). It has CC/cv capability. I have borrowed an LN-25 Wire feeder to try to do some wire welding. The ln-25 come with .045 flux core wire (don't know the brand but it old). I am having a lot of trouble dialing this welder in. I have my polarity correct and it will run for a few minutes and stop. I am having a lot of trouble with bird nesting. I just do not know enough about the machine. The owner who is my brother says it welds great with solid wire and gas but I have not tried that yet. This is first experience with wire feed of any kind. I have always been a stick welder. It seems like the machine has a hard time pushing the wire though the line but when I tighten the feed rollers it birdnests. Any suggustions.
Stan from central Arkansas novice

Stan .045“ wire is right on the edge of having to have a dedicated flux core gun. Are you trying to run self shielded flux core through a regular Mig gun? And do you have serrated drive rolls in the LN-25?

Yes I do have serrated rollers . I will look at the type of gun I have today and see the model number I did not know there was a difference in guns for sizes of wire. There is no label on this wire either, it is on a heavy wire wheel I will try to get some pictures of my stuff and maybe that will help out with the diagnosis. I will try to post with more info tonight

For self shielded flux core I really like Lincoln’s K-126 Guns. The problem with these guns is you can not replace the liners, so you need to blow them out once a week.


Few months ago I bought a K-126 Pro gun. You can change the liners in these guns.


But they use different contact tips, and thread protectors than the regular K-126 guns.

Stan,

One possible problem is the "old" wire.

Are there any bits of surface rust on the wire? It should be slick and smooth with no rusty or rough-textured spots, as these will give you fits.

You can add a cleaning pad and/or a lube pad where the wire enters the feed roller block to reduce contamination in your liner. Here's an example: In the image on the bag, the red pad is a cleaner, and the black pad rubs a microscopic amount of weld-compatible lubricant on the wire to allow it to feed through the liner easier.

With the knurled rollers, it's entirely possible to be too tight, and leave sharp indentations in the wire, which will also give you trouble.

Steve S

I have some pictures of my equipment but not sure how to post them. the old wire does have some rust spots on it for sure. the gun is a magnum 400 and my brother says the wire came with the machine when he bought it. I got a new .035 roller and a gas regulator from him for this machine last night. I have not bought any wire yet, or any gas. The gun I have doesn't look like the ones you guys have. I can post the file on here but don't know if it will show up as a picture. I am going to build a stand for an old midship hale fire pump out of 2x2x1/4 square tubing and that is why I want to wire weld it so it looks nice . It will be displayed in my fire station and I will use it as a training tool. As for the knurls on the wire when it comes out they are pretty deep and sharp. I think I have the tensioner let all the way out but I am not sure about that. I am running on DCEN on my welder and the wire feeder and my welder has a separate CV lead and a setting that says 17 to 28 volts as well as a dial that reads from 0-10. On 4, the volt meter on the wire feeder reads about 18-19 volts when welding. the wire feed speed on the feeder I kept trying to adjust and got up around 190-200. it would weld somewhat well but still not anything to write home about. I kinda feel dumb about this because it is so much easier for me to just stick weld. I just can not let this machine win.

You need to look at some Lincoln charts and make sure you have it hooked up correctly.

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Are you talking about dual shield wire? Which requires gas! Whole different animal from self shielded wire.

That is one problem I don't know what kind of wire it is exactly. Gonna buy new wire and start over

Maybe this will help.
http://www.lincolnelectric.com/en-us/su ... rodes.aspx