Mig Welders

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"RogerN" wrote

I have found that with thin sheet metal, it is better to make a series of tacks, rather than long runs, as those generally fall through. Use the color as a guide. Make a tack, and wait until it cools down to yellow fading away. From the available glow of the light of the puddle, you should have enough light to already be positioned for the next spot. I do it in a push situation, pushing the next puddle in front of the other, rather than pulling the wire away. Got some mighty fine stitch welds like that, and far less burnthrough. If you burn through, it's a bitch to fill up the hole, or stop and make a patch, and the patches look like hell. Jump around and let it cool inbetween spots to keep distortion low.

Steve

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It probably can. My Millermatic 210 can too, but the little red box does it sooo much better. Depends on how demanding you intend to be about your welds. My Millermatic 210 could do it but it'd probably require more grinding and cleanup.

Having continuous heat control on the Century makes it look promising, but Century is/was a second-tier supplier not as good as Miller and Lincoln. BTW, Hobart and Miller are the same now.

They look similar, but does the Weldpak have continuously adjustable heat (voltage) vs a 4-position switch?

I think the Weldpak line was/is a consumer "fighting model" sold thru outlets like Northern and HD. I would not assume that it works as well as an SP135 Plus for autobody. I also wouldn't assume that it doesn't; try before buy if possible.

YES.

Steps are OK for 1/16" metal and heavier, but for thin body metal the ability to tweak to "just right" makes a huge difference. The difference between good fusion and burnthru is rather narrow with thin metal so getting heat, wire speed and welding speed all just right makes all the difference.

I had an import MIG with a 4 position switch. I wasn't really looking for another one when the guy at the welding store had me try the little Linc. WOW! He was chuckling as he said he knew I wouldn't leave without it. I definitely got my money's worth out of that little red box doing rust work on the fleet at the time.

It might. Continuous voltage control sounds promising.

Patching burnthrus is actually quite easy with continuous voltage control. Just dial back both to where it works well for closing a hole.

I would strongly recommend spending a couple of hours practicing making and patching burnthrus on thin scrap. It'll be time very well invested. Then when (not if) you get a burnthru, rather than cursing you'll just grin with the thought, "no worry, mate, oy kin fix that in a jif."

It definitely helps to have the metal bright clean. it is possible to MIG weld thin metal that is dirty or has some surface rust or paint residue, but it is not possible to get a good weld under those condx. Gunnner is right on when he suggests having plenty of scrap practice material at hand. I nearly always "calibrate my hands, ears, eyes and machine" on a bit of scrap before I start welding for real if I haven't welded for more than a few days.

That's not so true of TIG because TIG is so amenable to puddle control, and independent real-time control of both heat and rate of filler addition clear down to zero. It's less true of stick simply because stick is seldom used on stock less than 1/8" and there's a lot of latitude even with 1/8" rod and 1/8" stock.

Nope. 4 postition switch. But for $100-150 used...shrug I ran some .020 wire with it not long ago and it was very usable, but I did have to play with torch height a bit while welding before I found a compromise height.

Indeed.

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

You are correct. One of the main differences between the machines sold at welding supply houses and the Borg was the infinite vs. step heat range. With the infinite variety, you can up or down just a tad. With the jump, it's just that, one's too hot, one's too cold. IIRC, the interior parts in the Borg models had more parts made out of plastic. I opted for the SP175+ so I'd have all the bells and whistles. Except for the cranky trigger switch, which I am about to change if this last fix doesn't cure it, I got no complaints whatsoever. Had been a Miller man before that, but either is good.

Steve

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I like to "dial" mine in, that is, find out what settings work perfectly for what, then keep a little 3 x 5 notebook of the settings. Compensating for too low/too high amperage by adjusting stickout range is not a great thing. If your stickout is too short, it burns back into the contactor tube. If it is too long, you end up with a bb on the end of the wire, and either have to trim it, or start with a bit of metal on the end of the wire.

I tell you, getting it "dialed in" on some scrap, then using the staggered spot sequence will give you some dang pretty welds that make your work look very very good. Also do rosette welds, where you drill a 1/8 or + hole in one side of two pieces of metal that are going to fit flat against each other. Clamp, and fill the hole, making it a really good spot that is as strong as some of those that the robots do in the factories. Staggered rosettes are also good for positioning a piece before welding it all around to keep down warpage.

Steve

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What he said.

Steve

Probably either: a better gun, comes with a gas solenoid kit, has the infinite vs/jump heat ranges, or has better component parts, and perhaps even an extra set or two of rollers. First time your liner takes a dump, put an .045" in there, and forget about it for about five years.

Steve

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I've never had good luck with long runs on thin stuff. I have had good luck with staggered spot welds. If you make long runs, you get a LOT of warpage.

Or, that was my experience. Keep a little diary, and it will keep you from experimenting around so much with scraps. It will also keep you from blowing so many holes in stuff.

And importantly, torch angles so you make the puddle flow to the edge from the flat piece works better, because if you start right on an edge, you will burn it up instantly.

Get lots of scraps and practice a lot. Particularly spotting, rosettes, pushing instead of pulling, staggering, and recognizing the color of when it is just right cool to stack the next spot. And learn how to stack your spots like the "stack of dimes" or snazzy looking TIG welds.

I'll do some soon and post them to flickr. I got a couple of projects coming up. Might even do youtube. Would sure like to catch that on video if my camera will cooperate.

Steve

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Indeed. Ive got a few MIG welders..and the little Weldpac 100 gets a fair amount of use when Im out in a customers shop.

Gunner Lincoln Weldpack 100 Dan-Mig 200 Miller 35 (straight wire) Miller 35 Husky 300 Feeder (aluminum) Airco PhaseArc 300 (300 amp 3ph) Ranger 9 with LNS-8 feeder

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Use the Century! Those little welders don't do sheet metal well, especially imperfect sheet metal. Dial down and "stitch weld" with short "baps" with cooling time between close welds. Have the metal as clean as you can.

It looks like today's Century welders are made by Lincoln. The Lincoln sounds great, the current model I'm finding is a SP140T, do you know if one of those are suitable for auto body like I want? Currently I plan to get a bottle of Gas and some sheet metal and start practicing with the Century and looking at/for a Lincoln 120V SP.

RogerN

The punch/flange tool comes in handy for making those holes. Cleco's are also a good thing to have for sheetmetal work.

The 4-position heat selector on the Hobart Handler 135 that I use, isn't an issue for me, or for a friend who has primarily used a basic Lincoln model for years.

If I feel that the selected range is hot for sheetmetal, allowing a little more wire stick-out, or moving a little faster keeps everything working well. The wire feed speed is infinitely adjustable, so that allows the user to dial-in the speed of movement too.

Last fall, a friend and I tackled a windshield opening repair job on his big motorcoach. The Hobart worked fine with new sheetmetal fitted into openings where the rusty old steel had been cut away. The welding was done with C25 gas and .025" wire at the Heat 2 setting with essentially no problems. There was a lot of rust damage that resulted in numerous water leaks, but the more serious problem was that the 2 huge, very expensive windshield sections are nearly vertical, and they're glued in place. I wanted to do more experimenting with the Heat 1 range and new sheetmetal, but got sidetracked onto something else.

I tend to push weld in most cases, instead of the drag technique, for better visibility and more predictable/desired results.

I also have another MIG welder that I haven't used yet. It has several additional weld features that aren't usually found on basic units, since it was marketed to autoody shops, but the extra features may not be very significant. It's an older Solar/Century 120VAC model with an integral wheeled cart/storage cabinet. There were a number of accessories and methods described in the manual that I hadn't heard of before. There is an adapter for holding a carbon rod, which can be used for heating (bending or shrinking), but also for brazing with common brazing rod used in conjunction with the attached carbon rod.

I have no personal experience with the SP140T, but it has 4 taps rather than continuous control. The SP140C would be a better choice for autobody.

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