MIG welding settings

Hi all, I'm one of those woodworkers branching out into the world of metal working. I've started a couple of little projects to get my bearings and am hoping to start to get a "feel" for it. I have some 3/16" mild steel plate I have cut and need to weld back together into the project, including outside corners, "T" joints and butt joints. Most joints I will be able to get to from both sides if I have to. I have a Canox (actually a Miller) 90 amp mig loaded with .03 wire, using 75/25 argon/CO2. Just wondering what settings you would use? My understanding is that this would be near the max of my little welders ability, so should I slow the feed down to let the heat penetrate a little more? Any advice would be great. I bought the welder used, so don't have the instructions, and the charts are no longer on the machine.

Thanks!
Brent

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Originally Posted by brent stanley

Hi all, I'm one of those woodworkers branching out into the world of metal working. I've started a couple of little projects to get my bearings and am hoping to start to get a "feel" for it. I have some 3/16" mild steel plate I have cut and need to weld back together into the project, including outside corners, "T" joints and butt joints. Most joints I will be able to get to from both sides if I have to. I have a Canox (actually a Miller) 90 amp mig loaded with .03 wire, using 75/25 argon/CO2. Just wondering what settings you would use? My understanding is that this would be near the max of my little welders ability, so should I slow the feed down to let the heat penetrate a little more? Any advice would be great. I bought the welder used, so don't have the instructions, and the charts are no longer on the machine.

Thanks!
Brent

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Brent,

I'm not sure what to tell you about specific settings. My MIG experience was very limited and many years ago, but one thing we used to do to "create" penetration was to bevel both sides of the joint with a grinder then fill the crevice, with multiple passes, if necessary. If nothing else, I would practice on some scrap to get a feel for it before you go to your project.

Hope this helps,
Charles

Number one piece of advice is the same as woodworking: try it and see, on a piece of scrap first.

That said, I suspect that most welding calculators will give you a recommendation that's out beyond the range of your machine, and your biggest decision will be whether the limited job you can do with 90A will be good enough.
(For example, here's Miller's online MIG calculator for solid wire : http://www.millerwelds.com/resources...calculator.php. It recommends .035" or even .045" wire at 160-170A for 3/16 steel.)

Thanks for the pointers guys. I forgot to mention that I've bevelled the joining parts actually, and fortunately maximal strength is not required for this, but that calculator is a great resource for future projects. What I'd like to do some day though is build a trailer frame so of course weld strength will be important.....coming from skills and machine capacity. Would welding from both sides extend the capaciity somewhat?

Check out the link below, it's to a story on my metal site that talks about wire speed and related things. that is a big part of getting a MIG to weld right. You still have to practice and experiment but that;s half of the fun anyway.

http://www.newmetalworker.com/Howto/migwirespd.html

Miller also has mobile apps for their calculator: http://www.millerwelds.com/mobile/

There isn't a whole lot to be gained by welding from both sides in most cases - and often makes fitment a little more tricky. Typical method is as Charles stated - bevel the edges, do a root pass, and then lay in passes over top of that to get what you need. You could possibly do that and then go back, clean up the backside, and lay a bead from that side if it were accessible. Another thing that will gain you some penetration is to switch to a flux-cored wire.

For years, I made do with a 110V MIG and a 220V stick welder which I picked up cheaply used. I only had maybe $500 into the two setups together. I've since upgraded to a 250A/220V MIG and a 250A/220V TIG that I also use for stick occasionally. But the MIG/Stick combo worked well - thinner stuff with the MIG and thicker stuff with the Stick. Keep an eye on your local classifieds for awhile and you'll likely turn up an old Lincoln stick welder for a couple hundred dollars.

Thanks again folks. I also have this little machine: http://www.victortechnologies.com/th...rodID=W1003202

Came as a promotional with my plasma cutter......it's been a lot of years since I used a stick machine, but maybe this is the better machine for what I'm up to now?

Thomas: I've been told that even though my little MIG welder is very small, it's a good quality machine. It's a long story, but it only cost me $100 with hose and regulators, a bunch of tips and full spool. Would you recommend I hold on to it even after I get a bigger MIG machine for heavier material? I've been told that a good smaller machine is better at working with lighter material, than a larger machine dialed down is, but that might not be correct?

Thanks again guys,
Brent

Thanks for the link Tom, I'll study that when I get home tonight.

Cheers,

Brent
A couple of things that might help you. You may be surprised by how much things move when you weld. Secure clamping is very important but one of the great things about MIG is that you can tack things together and quite often this works better for me than the amount of clamping I would have to do otherwise. I always test my settings on a piece of scrap of the same thickness or even mock up a similar joint with scrap if it's something important. It will help you get to know your welder and you will find that you don't have to adjust that much later. Be sure you have a good ground connection to the work, keep a short arc and grind off rust/paint if using old material. I think most of the time people tend to set their mig welders too low, don't be afraid to crank it up but watch your duty cycle. And there's always that favorite rule of thumb "sound of frying eggs" indication that settings are good.

Hi Chris, great advice thank you. I have recently experienced how much the metal moves when you weld actually......at first I thought I was going nuts because I was sure I had it clamped at 90, but after welding (practically speaking after the point of no return!) it was over 5 degrees off! The metal moved so much, it overpowered the spring clamps I had on my 90 degree guide. But if I understand your suggestion, I might be better off just tacking it together quickly in a few points along the final seam to lock it in before adding a lot of heat to it when I weld the rest of it. I'll try it out....makes sense. Thanks again!

if you have an iphone or an ipod, there is a miller welding app that is very helpful for settings