Here's my problem. I'm trying to make a header for a small engine. I have 1/4" flanges made and I am using 16 gauge tubing for the runners. I have cleaned, beveled, and fitted the tubing to the flange. However, I am having difficulty finding a heat and wire speed setting that works consistently to join the two. My welds when joining similar thickness materials, like the tubing, are not bad, and I'm getting darn good at sheet metal, but I really **** at this thick-thin stuff and am getting frustrated!! I have a Lincoln 135 110V machine, CO2/Argon tank. I have .025 and .030 regular steel wire , .035 flux core wire, and a roll of the cored .025" twenty gauge wire available. If I crank it up too high, the penetration on the flange is good, but it often blows thru the tubing. If I turn it down, the welds look cold and are sitting on the surface. What kind of wire speed (slower or faster), heat setting (higher or lower), and technique (push, pull, vertical, something else) should I be trying? Am I just moving too fast?
this is going to be tough with a mig I think. but you could strike the arc on the flange near the tube and let the tube 'melt' into the bead. a tig would give you much more control over the bead, or a torch and you could braze the 2 pieces. a few mig tacs on the inside and a nice braze around the tube to the flange on the outside.
For someone who isnt familiar with directing an arc this is going to be difficult. The trick is to maintain a good heat that welds both materials well but you have to direct the heat in the direction of the thicker material. This allow both thickness to be welded at the same heat. Point your mig welder at an angle more directly to the heavier flange and at the same time watch to see that the thin tubing is blending into the weld....see if that helps.
Brazing sounds like an idea. The joints are pretty tight and I can probably get bronze or silver solder to flow pretty well. Think it would hold up under the vibration and heat?
I agree with 50shoe as far as how to place the weld. I do not know anything about tig but you should be able to do a good job with the mig. Leave your heat up high enough to penetrate the flange. With the two different thicknesses, put the bead more on the flange and work it onto the pipe. You need the heat up to where the bead melts into the flange or else the bead with fall off after a little use. As far as how to hold the electrode. I push the weld. Someone told be that you will push some of the contamination away rather than drawing it in. Neal edited: man, I type slow. All those posts while I typed. All good points to where it goes back to practice first. The other problem is that you are chasing the weld around the tube and not a straight line. I personally do not have much faith in bronzing it. Not strong enough.
keep in mind that you dont have to penetrate the plate any farther then the thickness of the tubing it will never be any stronger then the thinnest material good luck Zach
If your using a g*** shielding, then the flux core wire is not needed. The steel wire will be a better quality weld also. You mentioned that you can set the unit to where its pounding into the flanges & blowing through the tube. This is the heat wire speed you probly need. What I imagine is your concentrating everything directly into the joint. I'd recommend oscillating your hand (washing the weld back & forth) Now doing this oscillating, use a "J" type wash or motion. Meaning concentrating the arc to the flange & washing the puddle up onto the tubing. Does that make sense. Oh....you always push a MIG w/ g*** shielding. Never pull the weld. Thats for stick or arc welding. Carl Hagan
I might have missed it, but are you welding on the front or the back (gasket side)? If the front, try fitting the tube through the flange and welding from the back, then grind the bead flat but a little proud to the flange, so it will bite into the gasket.
this is gonna be frustrating, but stick with it- the advice about "leaning" on the heavier material is spot on (no pun intended.) I doubt that your first time out of the gate you are gonna throw a perfect bead around what is effectively the inside diameter of the pipe. so here's what advice I can give-hope it helps. I am ***uming the tubes are welded all the way up and already tacked to the flange from the outside. (3 points are usually plenty, just enough to grind out later-so they need to be in places where they can be accessed with your grinder later.) you need to be looking at the head side of the flange-with the pipes facing away from you. In a perfect world, you would be looking at the flange from above-I will explain why in a minnit. #2- make sure you can walk fully around the header comfortably. #3-make sure your ground is attached to the flange, not one of the tubes-as you weld, the weight of the ground cable can drag a red hot tube just far enough out of alignment to make it an official pain in the *** later. #4- if you are looking at the flange from above, you will notice that you can't comfortably make it to more than about 1/4 of each tube at a time. That's fine, because that's all you are gonna weld at once anyway. get comfy, and figure out which side to start at where you are least likely to cook your support hand. #5- once comfy, you are gonna get started. the method we are talking about uses the "parent" metal to absorb the largest amount of the heat. _I like to use .023 wire for header work, because it will allow you to crank up the wire speed and heat and build a "larger" bead that can easily be ground later. Focus the Nozzle toward the flange- if you have your heat right, it will melt pretty nice, and you can "dip" the wire toward the thinner tube and pull some of the flange steel with it. once you have done what will probably amount to about 1/4 of each tube, move around again. and don't forget to let it cool off completely between p***es (it doesn't hurt to test fit the header between p***es, either.) don't use water- you will make the welded areas brittle and prone to rust. (even the best welds have some degree of porosity to them, and you can trap water into the weld.) if you gotta get it done in a hurry, use compressed air to chill that puppy out. one last thing- to ensure nice solid welds, when you begin the next p***, start on the last weld you completed- Mig starts cold, so you want to get into the steel by the time you hit the previously unwelded steel. and remember this. unlike a 2x4, if you make it look bad, you can use our friend the grinder to clean it up.
Thanks for all the tips. I'm gonna hit it again this weekend and I'll post some pics of the results. I had four sets of flanges made and I have a lot of tubing, so if nothing else, at least I will **** a little less at doing this, I hope.
I agree with everybody's advice. The main thing is trying to get more heat into the flange and less heat into the tubing. You can use a die grinder or a file to "port" the excess weld out of the opening when you're done, but if you do it right, you won't have much metal at all to port. I have used silver alloy brazing to strengthen headers and it seems to work fine. I used one of the cadmium free silver alloys with a higher melting point. But you need to weld the tubes to the flange on the inside first. For the silver brazing, I figured out that you have to etch the area well with a rust stripper to etch away all the blued steel garbage from the inside of the joint due to the welding. Then I slathered some black flux (it contains fluorine salts that produce deadly toxic fumes), then I heated it up red hot and the silver flows right in there and makes a nice finished looking fillet. It's nice because it makes the headers feel really solid and takes away some of the tinny ringing sound from the header tubes. It held up fine and a ceramic coating works fine over it.
I like this idea, to finish off you could add a little braze around the outside joint just enough to create a small radius and fill the gap. This would give an ultra clean look........ very top pro. Get it Hot!..... hit it Hard!
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