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welding to unibody...

jjvande

NAXJA Forum User
hey, happy Holidays

so im the prowd owner of a new millermatic 175 mig welder. i'm new to mig, but i have tackled a few projects with a stick welder.

My question is: what sort of wire size, and settings do you gurus use to weld to the unibody? I'm thinking of boxing in some sections of the unibody to bolt skid plates too.

also, ive heard of using an argon/co2 mix for the gas, i was also told that you could use just CO2. The cost of CO2 is much less than argon...and the tanks are smaller...last longer. any experiences?


what do yo think?

Thans
-J
 
I used a Lincoln Weldpak 155 (220v) with .030" wire and CO2+Argon. The heat setting depended on the thickness of the material I was welding to the unibody. One key thing is to remove as much of the undercoating/seem sealer as possible. That stuff (even when it's on the otherside of the area you're welding in) will super-heat and blast through your puddle. Not only will it ruin your weld, but it hurts like hell.

When I was welding 3/16" plate to the unibody, I'd set the heat to 'E' (the highest setting) and keep the heat on the plate-side.

When welding unibody seems, I set the heat to 'D' (or even 'C') and kept the puddle moving.

I guess the best tip I could give would be to start with your machine set a little low, and increase the heat till it sounds/acts right. If you're going to be welding 1/8" (or less) to the unibody, I would consider .025" wire.

My $0.02
 
JSR gives good advice. While CO2 is cheaper, I don't like it. If you can't afford $25 worth of gas that last 8 hours, maybe you shouldn't be welding anyhow. The mix is a little cooler and I find the puddle seems to be easier to work.

The unibody is dipped in galvanizing, when welded on it puts off toxic fumes. Try to get the area you're welding as clean as possible and stay in a nicely ventilated area, just don't have a fan blowing on you or you might as well use fluxcore wire. I use .030 typically unless I have .023 in the machine from straight sheetmetal use. Get the puddle working on the thick material and work it into the sheetmetal. You'll figure it out with enough practice.

Sean
 
One Ton hit it on the head.Use .030" and control your weld by working into the thinner material from the thicker.75/25 is better suited for thinner materails and also requires almost zero cleanup(loks closer to a TIG weld).Use CO2 when welding thick materials due to the deeper penetration!
 
The other thing nobody mentioned directly is that the galvanized coating will cause your weld to outgas and get little volcanoes in it while spitting the molten metal at you. Like the man says get it as clean as possible. If you really want it to weld better, sandblast the galv off the seam before you start. If you aren't an old hand, it will make life a lot easier. A cheap $20 sandblaster from harbor freight will do just fine. Then add $2 worth of play sand.
 
Straight C02 welds, seems some harder than mixed gas welds. I usually use 18% Argon, for structural welds, that hold something under stress. And C02 for joining welds, sheet metal and such. Occasionally use C02 for brackets and mounts. Most times, I run longer welds than actually necessary anyway. A good tip spray, will keep the dirtier C02 gas welds, from messing up your tips, dirt, rust, paint and such will typically do them in, faster anyway.
If you read the labels, they usually list the moisture content of the gas. Resturant gas (beer and coke machine) may be acceptable. The C02 my buddy the Coke guy, throws in my driveway, from time to time, works just fine. A big bottle lasts forever.
I keep a selection of rubber plugs, an antenna drill, and a undercoating sprayer with a long nozzle, handy, Treating the inside of the frame, after welding, with a light undercoating (I´ve used undercoating primer with good results) will slow down rust. I sometimes use rustolium rusty metal primer, fairly thin, in my undercoating sprayer, with a two foot plastic nozzle and a coil tip, on reasonably clean inside frames. Cold zink spray or rustolium rusty metal primer on the outside welds.
 
wow, thanks for the great info..!

sounds like most of you like the Ar/CO2 mix because its easier and it permits cleaner stronger welds..makes sense. i'll just have to start practicing and see what kind of boogers i can make:)

I was thinking of welding some 3/16" c-channel about 10" long to the unibody frame so that i could bolt a stout skidplate to the region behind the Clayton cross-member...any thoughts?

Thanks
-J
 
jjvande said:
wow, thanks for the great info..!

sounds like most of you like the Ar/CO2 mix because its easier and it permits cleaner stronger welds..makes sense. i'll just have to start practicing and see what kind of boogers i can make:)

I was thinking of welding some 3/16" c-channel about 10" long to the unibody frame so that i could bolt a stout skidplate to the region behind the Clayton cross-member...any thoughts?

Thanks
-J

Some of the local guys have had good luck using 4x4x3/16 box tubing and slicing off one side. It forms around the "frame" quite well and with a bit of slicing you can run it from the front to the rear.
 
Like Old Man mentioned, spreading out the load works well. If you bang a 4 inch rock on the frame, you got a four inch dent, if you bang the same rock on 10" bracket, you probably have a 10" dent, though not as deep. I usually make brackets or mounts, with the thought in mind, to spread out the load. Longer than necessary. Just a thought, but 3/16 inch material, seems like a bit of over kill. 1/8" material would probably work just as well, if it dents, it will probably be minor. 1/8" diamond plate , is steel, got a good memory and is pretty springy. Some of the thicker box steel is milder and doesn´t have the memory of thinner, higher quality steel. In the end, it might be just extra wieght.
Whatever you build, is only as strong as what it is bolted/welded too. I´ve seen guys build 1/4" thick, bumper brackets and weld them to the last 2 inches of the frame. Probably could have used material half as thick, used a foot of frame, ended up with something stronger, with a little flex and crush built in. I like to think a little crush, into my constructions. If your 2 ton Jeep, hits something with just a little velocity, something is gonna give. A controlled give, spread over a wider area, often works better than armor.
 
I think the reason for the 3/16" is that the "ID" is smaller.It is a better fit on the uniframe.If you were to use 1/8" it would be sloppy.
OlyWa
 
I use 3/16 for abrasion resistance. I've got several gouges in my 3/16" rails that are deeper than 1/16". Damn shopping carts. :)
 
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