Thread: Wire feed problems "need help"

I have a problem with my Uni Mig 270. I have been welding alloy for ages with it and had no worries at all; today I put a new liner in it and the metal tip in, all good so far. The steel wire is 0.8mm and the tip is 0.9mm, the liner is in fact my old alloy one which is 1.2mm. The steel copper coated wire I have has been sitting around for 2 years and has rust on it. Every time I press the trigger it bunches up at the drive. Could this rust be the problem or am I going nuts, well I have already gone nuts trying to get it going. The drive well isn’t slipping and I thought there was enough room for the wire to travel through. Thew wire isn’t heavily coated in rust or even fully covered in it, its more spotted rust almost like a Dalmatian dog. I’m thinking it’s the wire but some one will point me in the right direction. I’m not a welder buy trade, I have spent most of my time welding alloy and haven’t had all that much to do with steel.

Stu

Can you take a picture of the unit showing the feed rolls and the start of the liner?

Check that the liner goes all the way to the rollers, if there is any gap of more than say 5mm between the rollers and the liner this is what usually happens.

This was the case at the start, but then I moved the liner further in until it was touching the roller. I still had the same issue, in having said the roller also has a bit of light surface rust on it but in the groove it seems shiny.

Stu

Originally Posted by Stufart

The steel copper coated wire I have has been sitting around for 2 years and has rust on it. Every time I press the trigger it bunches up at the drive.

Stu

Hi Stu,
There is no doubt in my mind as to the cause.It is the rust.
Run out the wire by hand until you get the top layer off the spool.get down to where there is no more rust .It is important theres no more rust.
Pull the liner ,wash in kero (coil up and into a clean twenty litre drum -lil bit of kero swishing around in bottom -ok, tip out kero do same with methylated spirits-) .While your at it chuck in the roller too it won.t hurt it.

This is to clean the rust crap out the liner that is undoubtedly there.Don't try and weld yet as it will contaminate the wire and you will get inclusion and porosities and not know where they are coming from

Set up pressure on rollers by doing this -Wind down the spring pressure bit by bit until wire feeds in.

Holding the ingoing wire between thumb and finger slacken off the feed roller until you can make the wire slip and not go through the rolls-holding it back-with your thumb and finger.

Put a length ways cut a an old ear plug and place over wire as a cleaner.

When not using wire place in a plastic bag with some dessicant and seal with a twist tie.


.It will work ok.!
Grahame

Thanks heaps mate, every thing makes sense now. It helps when you ask on forums like this. I will just buy new fresh wire and a new liner I think just to be sure. I striped heaps of wire off the spool and its still got rust on it. I striped even more today but still got rust on it. I will give it ago tomorrow and if I cant get down to fresh wire I will go straight up to BOC and buy some more. Perhaps you can tell me, I have a uni mig 270, would you know what setting I would need on 4mm mild steel? I have 3 course settings and 7 fine settings and my wire speed goes up to 10. Thanks again for the help.

Stu

The settings for 4mm are something you will need to adjust,as it just a bit hard to estimate as all machines are different.

A guess would be Course NO 1 position and Fine No7

Adjust up or down from there working on too hot or too cold.

The wire speed should be tuned until you get the max pitch with that tearing/cooking bacon sound.
That should get you going
Grahame

New wire, new liner, new tip and wow what a diffrence. It has never welded so good. Thanks very much for your help.

Stu