Mig Speed Woes

[Katoh]

Gentlemen
A question to the welders and boat builders on the forum. I have a CIG brand 275amp mIg 3phase, that i use with a spool gun for my aluminium welding. Lately I have had all sorts of wire speed feed dramas. I cannot get enough wire speed and at times fluctuates. I have checked the circuit board and all is fine and the switch seems to be operating OK, but one thing the switch does not seem to be the original. The control switch is a 3 prong 1kohm. How do I get more speed in the feed?
CIG now BOC aren't interested in this 28 year old machine they want be to buy new but there's nothing wrong with this one. Only the feed rate of wire.

[Chase_B]

Sounds like you might have some slippage going on if you still get wire to feed but its spiratic, either the drive wheels or the gear drive between the spool gun motor and the drive wheels ?
Just a thought

[Katoh]

I thought about that, but you can actually here the motor rise and fall, must have something to do with the control unit. I had a thought of using a larger resistor switch but I am not sure if the more control resistance the feed rate increases or decreases?
Thanks

[pistnbroke]

first find out what sort of motor is driving your wire ...will not be 3 phase..Probabley a DC motor for which its easy to build a new controller ...post some pictures ...thought ....motor bearings or brushes OK at 28 years ??

[Wynand N]

Im gonna be devils advocate...

Worn inner sleeves for feed wire cable sometimes have similar symptoms. Have you checked it lately? If worn, replace with teflon unit for smooth feed.

[pistnbroke]

personally I never found the teflon to be better than standard but if its aluminium you are using U not V rollers are the go

[pdwiley]

Originally Posted by Wynand N

Im gonna be devils advocate...

Worn inner sleeves for feed wire cable sometimes have similar symptoms. Have you checked it lately? If worn, replace with teflon unit for smooth feed.

Wynand, he said spool gun so I'm assuming there is no liner. I know my Readywelder spool gun just feeds straight to the tip.

PDW

[Chase_B]

if it's a spiratic "IPM" issue,..might be the spool gun motor is in need of rebuilt,..one way to find out ,.. unplug the feed wires to the gun and do an ohms/voltage test off the machine, if you get constant feed out of the machine ,..the problem is in the spool gun ,..chances are it's the motor ,..switches usually work ..or they dont,..unless its like a "TIG " slide switch ,( potentiometer switch)..which I don't think is the case on most spool guns

[Katoh]

PDW
You're spot on! I'm using a spool gun which is new only a year old, nothing wrong with the gun it seems to work fine. I'm not sure if the motors are current or voltage controlled? how would you test?
I even had another thought maybe I could use a separate power supply to run the spool gun motor and control it through a relay?

[Chase_B]

ok newer spool gun ,..which model ,..some require a control box depending on power supply/machine

[Chase_B]

I was going to get a spool gun for my hobart welder,..but it turned out to be cheaper to buy a new machine that came with a spool gun,..I ended up having my boat built before the machine came in so I cancelled,..I used an 8 foot lead with an .045 tip on my regular mig welder,..I put double wipes on the wire before it entered the lead,..I could run 6 rolls thru before the liner got clogged ,..luckily I had extra liners,..my impatience cost a little more for liners ,.which was allot less then the cost of the new machine ,..and I built only one boat

[Katoh]

The gun is a 250amp Miller, well I personally think its some generic thing as I have seen other companies sell the same one under there name as well. I had a thought if the gun motor was 12v and the mig was 24, but that would be opposite too much speed. The other thing I dont even think I have a torch that machine.

[Katoh]

Gentlemen
Many thanks for the inputs, ideas and places were to look. I tried another switch which had 5k ohm resistance and found that max speed was at 2.5k ohm's, the switch that was in the machine only reached 0.9k ohm's. now we have a decent wire feed and with 1.2mm wire achieving a good penetrating weld.

[Quatsino Boater]

I am very vamiliar will miller spool guns, If you are using the 110 voltAC control box with it WC-115A, it could be something as simple as the voltage pickup clamp not getting a good enough contact. Using a 1lb gun on alluminum you should be Constant current. As you back away the contact tip from the plate the constant current welder will want to keep the same amps ,say 200. The voltage will have to adjust in order for everything to stay in status quo. The voltage sensing pickup will detect this and it will speed up your gun.

another thing to check is your rolls. They should be knurled. they could be worn or just the wrong type , bare for steel. Or they could just need more tension. It could be the wrong size as well. Running .035 wire in .045 feed rolls will slip.

Another thing is change your contact tip or at least use an oxy/acet tip cleaner in the contact tip every now and then. If you run the contact tip to close it could be causing the tip to heat up and you may get galling or partial aluminum melting at the tip. Check your stick out.

Finally whatch out for bad case lots. I have found out several times out of a case of 1 pound spools , several individual spools will just be bad and fussy.

I hope this helps. The miller unit, either the old Miller spoolamatic 30A or Miller 15A's were rock solid dependable units.

[Katoh]

Hi Quatsino Boater
Thanks you given me some very good tips, that Ill put to practice.
The machine is an old CIG mig 415v. it is a little different from your 110v machine. As stated the control knob was my problem , but I acquired the welder with the problem and was told that there was a feed problem with the machine, my thoughts automatically AH! Motor. but using a spoolgun we bypass so all must be good. Good yes corrected NO, till now.
The biggest hassle with the spool gun is finding the spools, and expensive to-boot. I'm thinking I might buy a 6kg roll and make a unit were I can just re-roll the used spools. I look at it like this, If you run out of line on your fishing reel you don't buy another reel, do you? The only thing is I would either have to guide the vire with a cloth or gloves so not to contaminate it.