Millermatic 200 Welding Amperage Range

[89vette]

I have an old (80's?) Millermatic 200 I bought used and am trying to spot weld sheet metal with it and am having a heck of a time, keeps blowing through the metal. Using .023 wire, 75/25 gas, 3/8" stickout, 25 cfh. I followed the recommended settings and was having blow-through problems so I turned the voltage down to "1" and turned down the wire feed speed and it didn't help, keeps blowing through. Does anyone know the welding amps at dial settings 1 and 2? Even though it says it can do thin sheet metal I was wondering if the amps are just too much. I do have the manual and can't find it in there. I checked new machines and they all seem to start at 30 amps no matter what machine it is, but not sure about the old ones. Thanks.

[M J Mauer]

Welcome to the forum.
If you are spot welding why are you using gas and wire?

[H80N]

I have an old (80's?) Millermatic 200 I bought used and am trying to spot weld sheet metal with it and am having a heck of a time, keeps blowing through the metal. Using .023 wire, 75/25 gas, 3/8" stickout, 25 cfh. I followed the recommended settings and was having blow-through problems so I turned the voltage down to "1" and turned down the wire feed speed and it didn't help, keeps blowing through. Does anyone know the welding amps at dial settings 1 and 2? Even though it says it can do thin sheet metal I was wondering if the amps are just too much. I do have the manual and can't find it in there. I checked new machines and they all seem to start at 30 amps no matter what machine it is, but not sure about the old ones. Thanks.

Is it plain bare steel sheetmetal?? or is it galvanized or galvalume coated??

sheetmetal thickness??

are you using a "slotted spotweld" nozzle on the gun or are you doing this freehand? seems like a lot of stickout..

is this machine equipped with the SKP-35 spotweld control panel??
Spot Panel settings..??

[Cgotto6]

Welcome to the forum.
If you are spot welding why are you using gas and wire?

Because this is how you mig weld...with solid wire and gas coverage. How else do you suggest he spot weld with his millermatic 200? He is not running a dedicated spot welder.

[H80N]

Skp-35

Section 5-5 ... page 25 of this manual explains spot panel controls..

http://www.millerwelds.com/om/o1301q_mil.pdf

[maxstar300LX]

Skp35 panel WOW!

Hey H80N!
thanks for posting up the SKP-35 link!


the memory of purchasing my 1st welder, a 3rd hand, paint-challenged millermatic 35s back in the early 90's specifically to do sheet metal work on old cars.
i remember always pestering the miller distributor for that same panel as what I had was the SK-35 panel installed and badly wanted to try out the pulse feature.
When i finally got the funds to order it they told me Miller had raised the price and it was now discontinued, I would have to purchase a used one.
had to wait 30 years to get one on ebay... Yep still have the MM35, still works, still needs that paint job an the 2 miller stickers for the sides

Back pages are required reading for OP especially autobody work
e-70s-6 wire not -2 or -3 or copper coated crap makes sheet welds a lot easier less spatter and wets out nicer
copper spoon at back side is also a help especially if freehand welding
practice practice on clean clean scrap to dial in your panel settings and for reducing alot of spatter cleanup ,
adjusting burnback expect to go through a lot of tips to get it right
and the punch tool in the front pages helps with 'plug welds' technique like
Filling ice cream cone ,i find it faster than drilling holes
and using spot feature for sheet lap joints is also cool but fitup needs to be tight see first set of autobody panel pics

[89vette]

My fault, poor choice of words as I am new to this. I am not spot welding, I guess you call it skip welding maybe? Just one spot, one quick trigger pull, at a time. I do not have the spot weld panel.

I am working on a 66 Pontiac Tempest, so the sheet metal is 18-20 ga. according to my thickness gauge. I had some small pin holes so I tried to weld them over with one quick pull of the gun and it blows right through. Same for a patch, want to do one quick pull at a time around the perimeter planning to go around until the bead is continuous; can't even get started as it blows through.

Tried to practice more last night on some 20 ga. sheet but the .023 wire keeps jamming going into the liner after the drive roll. I fix it and play with it to be sure it works by doing short trigger pulls and long trigger pulls and it is fine but as soon as I try to weld it jams. Tried light, medium and heavy spring pressure on the drive rolls and same result, it jams. Guy at work thinks I need to be sure the cable is stretched out as much as possible and drape the cable at the gun over my arm to keep it straighter, so that is what I will try tonight.

Thought last night the pin holes might mean the metal is just too thin now, even though it feels fine when I knock on it. But it doesn't "sound" as solid as the passenger side that has no pin holes.

[H80N]

My fault, poor choice of words as I am new to this. I am not spot welding, I guess you call it skip welding maybe? Just one spot, one quick trigger pull, at a time. I do not have the spot weld panel.

I am working on a 66 Pontiac Tempest, so the sheet metal is 18-20 ga. according to my thickness gauge. I had some small pin holes so I tried to weld them over with one quick pull of the gun and it blows right through. Same for a patch, want to do one quick pull at a time around the perimeter planning to go around until the bead is continuous; can't even get started as it blows through.

Tried to practice more last night on some 20 ga. sheet but the .023 wire keeps jamming going into the liner after the drive roll. I fix it and play with it to be sure it works by doing short trigger pulls and long trigger pulls and it is fine but as soon as I try to weld it jams. Tried light, medium and heavy spring pressure on the drive rolls and same result, it jams. Guy at work thinks I need to be sure the cable is stretched out as much as possible and drape the cable at the gun over my arm to keep it straighter, so that is what I will try tonight.

Thought last night the pin holes might mean the metal is just too thin now, even though it feels fine when I knock on it. But it doesn't "sound" as solid as the passenger side that has no pin holes.

Sounds like you need to cut back to SOLID clean metal before you can put in a patch... probably way too thin... you will not weld through rust... it will pop and blow through..

Also... that old machine would probably like the process much more if you replaced or at least cleaned that gun conduit liner... it is likely full of crud...

Check the drive rolls and make sure that you are running the correct ones for the wire you are running..

making sure you are using a new contact tip of the proper size for the wire is a good idea too... they are cheap..

IN Addition... this may sound wacky but.... make sure that the Ground/work clamp has a good clean connection and is connected as near the weld area as practical... bad grounds account for lots of odd MIG arc problems... especially at the lower voltage settings..

[H80N]

Constant Voltage power supply...

BTW.... I should have mentioned this before...

The MM200 is a "CV" constant voltage power supply and output amperage is determined by electrode wire feed speed at a given voltage...

This is typical for MIG power supplies..

[89vette]

I had to buy the drive rolls and the wire so I know they are the correct size, and it is a new contact tip. Actually bought all new stuff for the Tweco gun it came with since it was in bad shape.

How do you clean a gun liner? It probably is dirty based on the condition of the machine when I got it. it is the spiral wire type from what I can see. Am I better off just changing it?

I did clean the practice metal last night before using it, but it could have been a better connection.

What is your opinion of the magnetic-stud-type ground connections? I was using that on the car.

Thanks for the info!

[H80N]

I had to buy the drive rolls and the wire so I know they are the correct size, and it is a new contact tip. Actually bought all new stuff for the Tweco gun it came with since it was in bad shape.

How do you clean a gun liner? It probably is dirty based on the condition of the machine when I got it. it is the spiral wire type from what I can see. Am I better off just changing it?

I did clean the practice metal last night before using it, but it could have been a better connection.

What is your opinion of the magnetic-stud-type ground connections? I was using that on the car.

Thanks for the info!

Gun liners are pretty inexpensive... like in the $20 range
and the newer plastic or tefllon liners allow the wire to travel much more smoothly than the spiral spring variety

what brand (Tweco?) and model gun do you have?? so we can source and price liners??

[MinnesotaDave]

I have an old (80's?) Millermatic 200 I bought used and am trying to spot weld sheet metal with it and am having a heck of a time, keeps blowing through the metal. Using .023 wire, 75/25 gas, 3/8" stickout, 25 cfh. I followed the recommended settings and was having blow-through problems so I turned the voltage down to "1" and turned down the wire feed speed and it didn't help, keeps blowing through. Does anyone know the welding amps at dial settings 1 and 2? Even though it says it can do thin sheet metal I was wondering if the amps are just too much. I do have the manual and can't find it in there. I checked new machines and they all seem to start at 30 amps no matter what machine it is, but not sure about the old ones. Thanks.

Based on the lowest wire speed for your machine of 85ipm and using .024" wire, I'd say your estimation of 30 amps is pretty close. (.024" wire figured at 3.5in/amp)

Quick question, is your voltage range selector cable in the low range hole, or the high range? (front lower left on the panel)

[89vette]

I will have to look at the gun tonight and see if there is a model number on it. No idea if the gun is original or not, but judging by the "well used" condition when I got it, the liner may have never been replaced either.

That is good to know, so a smaller machine probably wouldn't help with what is happening now.. The cable is in the low range hole. When I got the machine the cable was in the high range hole, but the cable tip and high range hole were a bigger size than the low range hole, so I couldn't even use low range. I replaced the cable tip & high range receptacle with the correct parts so everything is back to the way it should be.

Thanks for all the help.

[H80N]

You might consider stopping by a local body shop and seeing if they will give you a couple of scrap crashed fenders to practice on...

much better to develop and perfect your technique on some throw away tin...

rather than doing OJT and making your mistakes on a car that you care about..

if you have not already done so... you could download this MIG pamphlet...

it outlines the basic MIG parameters and guidelines..

http://www.millerwelds.com/pdf/mig_handbook.pdf

there is also some good info in the back of the MM200 manual..

[walker]

Welding up rust pinholes is not always easy. The problem is that you may have a tiny little spot where the rust broke through, but on the back side the metal is paper thin all around the hole. It can be many inches before you get back to full thickness metal. The beat thing to do is open up the hole until you have cut out all the cancerous metal and fit in a patch, then skip weld the patch in. It could be a nickel sized piece or it could be 30 square inches.