Again, hope I didn't screw anything up too badly. ~ClintThat is, if your stick welder had DC capability. I just burned some aluminum sticks a couple of weeks ago and I think on the box they just recommended electrode positive Ė reverse polarity. I found if you used them hot enough, and kept the end of the electrode very close to the weld puddle, you can make a fairly decent looking weld Ė and it looks strong.
The DCEP is recommended due to less penetration; DCEN is possible and may even be preferable for 3/8" aluminum. I use DCEN with the H418 rods on horse-trailer skid plates. Those H418's are 1/8" rods, btw.
Now the ribs, if they are thin, sound more like a job for a Mig rig.
I totally screwed this part up and got everyone (except Rich, who caught me) off-topic. He never mentioned ribs or spars...I read something into his statement that I shouldn't have. Nonetheless, your advice concerning ribs/spars is correct (as far as I'm concerned) in terms of MIG being a better option.
Now, if you have a big DC welder the cheapest way to go would be with the sticks, a Tig gun, bottle of argon, and flow regulator. When I worked in a paper mill this is what the welders used to weld stainless, aluminum, titanium, hastelloy, alloy 20 and some other exotics I canít remember. Now they didnít have the luxury of a foot pedal, but they did a good job of it just the same.
Not to get this thread too far O/T, but for the stinger-rig I believe you're describing, he'd either have to have an AC-capable welder for TIG'ing aluminum, or he'd have to be using one of the exotic Helium mixtures and quite a bit of Amperage (to GTAW aluminum with DCEN).
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Thread: Mig or Tig. I need help
08-27-2007, 06:05 PM #11Senior Member
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- Camden, SC
08-28-2007, 12:18 AM #12Senior Member
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- Aug 2007
- I live in Cheraw, South Carolina
If I am wrong I can always blame it on being old and senile, and if that is not good enough, I can also throw in lack of experience. That being said, I think I will have to disagree on the penetration and polarity in stick welding. I think you get your greatest penetration in stick welding when your electrode is positive (Reverse Polarity). This is because current travel is from the work to the positive electrode (current likes to go from negative to positive) and I think roughly 2/3 of the heat is released at the electrode. This causes the electrode to become super heated and it blows the molten metal from the electrode across the arc with great force penetrating the metal. The deep penetration characteristic of reverse polarity is why the 6010 (basically a reverse polarity rod) is your universal pipe root rod. I think in stick welding it goes something like this: Reverse polarity greatest penetration, AC next greatest penetration, and then straight polarity least amount of penetration. This is why a 6013 rod with straight polarity (electrode negative) is good for welding thin material.
Now when you go to TIG I think the opposite is true, that being electrode negative (Straight Polarity) gives the greatest penetration. With electrode negative 2/3 of the heat is at the metal 1/3 at the electrode. But how can this be different from stick welding causing greater penetration? I think it is because in TIG your penetration depends on heating up the base metal and then adding filler, rather than blowing the electrode across an arc into the base metal.
As for welding aluminum I think you can use straight polarity DC as long as the metal is thin and you donít need a lot of penetration. I think as long as the electrode is positive you get the cleaning effect with aluminum. It is just with AC you get the best of two worlds, cleaning effect and good penetration.
Now assuming I am right, does knowing about all these polarities make me a good welder?? Heck No. Welding is a science but just as important, and maybe more important, it is an art. You have to have good eyes, good manual dexterity, the right feel and you have to know how to hold your mouth right. These are some of the things I am having trouble with.
So check me out and see if I am right Ö. And if I am not, reread the first sentence.
I am still looking forward to meeting you sometime in Hartsville.6010
If I had know I was going to live this long, I would have taken better care of myself.
08-28-2007, 07:27 AM #13Senior Member
- Join Date
- Jun 2007
- Camden, SC
Correction To Post!!
You're correct...at least partially. I mis-read my information (or read it incompletely) prior to posting. I've attached an article on Miller's Resources page. It reads as follows:
FIVE TIPS TO IMPROVE STICK WELDING
Shellfish can make you a better welder. Simply think about CLAMS: Current setting, Length of arc, Angle of electrode, Manipulation of the electrode and Speed of travel. If you're just learning the Stick process, technically called Shielded Metal Arc Welding, remembering these five points will improve your welding technique.
Before leaping into the "how to weld" information presented later in this article, take a minute to review the following advice, especially if you've never struck an arc or are still debating which machine to buy.
Q: What type of Stick welder works best for all-around use?
A: A welder with an AC/DC output, whether its an electric arc machine like Miller's Thunderbolt or a gas engine drive like Miller's Bobcat.
DC welding offers advantages over AC for most Stick applications, including: easier starts; fewer arc outages and sticking; less spatter/better looking welds; easier vertical up and overhead welding; easier to learn "how to weld" and a smoother arc. DC reverse polarity (electrode positive) provides about 10 percent more penetration at a given amperage than AC, while DC straight polarity (electrode negative) welds thinner metals better.
Q: Does an AC output have any advantages?
A: Yes, if you need to weld on material that's become magnetized from friction, such as when hay, feed or water constantly rub against a steel part. A DC output won't work because of "arc blow," where the magnetic field blows the molten filler metal out of the weld puddle. Because an AC output alternates between polarities, it enables you to weld magnetized parts.
Q: How big of machine do I need?
A: A 225 to 300 amp machine handles almost anything the average person will encounter, as most Stick welding procedures require 200 amps or less. To weld material thicker than 3/8 in., simply make multiple passes - this is what professionals do, even when welding on 1 in. structural steel.
Q: I see the word "duty cycle" on product spec sheets? What does that mean?
A: Duty cycle is the number of minutes out of a 10-minute cycle a welder can operate. For example, the Thunderbolt XL creates a 200 amp DC output at 20 percent duty cycle. It can weld continuously at 200 amps for two minutes, and then must cool for eight minutes to prevent overheating.
Duty cycle and amperage are inversely proportional. Operating at 90 amps, the Thunderbolt has a 100 percent duty cycle, meaning you can weld without stopping. This inversely proportional rule is true of all Miller machines but does not apply to all machines made by other companies.
Q: What type of rod should I use for hardfacing?
A: Hardfacing rods can provide impact resistance, abrasion resistance or both depending on the application. Because the type of rod required depends on the type of soil or aggregate in your area, contact your local welding supply distributor and ask for their expert opinion. If you don't know a distributor, call 1-800-426-4553 and the operator can automatically connect you to the nearest Miller distributor. You can also locate distributors through http://millerwelds.com/wheretobuy/ ENDPARA]
Q: What type of rod should I use for general work on steel?
A: Common electrodes used for general work include 6010, 6011, 6013, 7018 and 7024, each of which has specific properties: 6010 electrodes penetrate deeply, while 6013 electrodes penetrate less. For much better bead appearance and work on higher strength steels (say for a hitch), use a 7018 rod. For better penetration on thick material, grind the joint to a 30 degree bevel (leave a nickel-width land on the bottom of the groove) and make multiple passes. Alternatively, make the first pass with a 6010 rod, then make a "cap" with a 7018. The 7024 rod is perhaps the easiest to use. Also known as a "drag rod," this electrode's thick flux automatically maintains the correct arc length, which allows you to drag the rod directly along the work piece.
Q: Do I have to remove rust or oil before welding?
A: Stick welding is more forgiving on unclean conditions, but it never hurts to clean parts with a wire brush or grind off excess rust. If you prepare well and have average welding ability, you can make a sound weld. However, even great welding skill cannot overcome poor preparation, as it can lead to cracking, lack of fusion and slag inclusions.
Now that you're ready to weld, remember CLAMS. Bringing all these points together in one moment of welding may seem like a lot to think about, but it becomes second nature with practice. And don't get discouraged! Stick welding got its name not because the electrode looks like a stick, but because EVERYONE sticks the rod to the workpiece when learning how to weld.
Current setting: The correct current, or amperage, setting primarily depends on the diameter and type of electrode selected. For example, a 1/8 in. 6010 rod runs well from 75 to 125 amps, while a 5/32 in. 7018 rod welds at currents up to 220 amps. The side of the electrode box usually indicates operating ranges. Select an amperage based on the material's thickness, welding position (about 15 percent less heat for overhead work compared to a flat weld) and observation of the finished weld. Most new welding machines have a permanent label that recommends amperage settings for a variety of electrodes and material thicknesses.
Length of arc: The correct arc length varies with each electrode and application. As a good starting point, arc length should not exceed the diameter of the metal portion (core) of the electrode. Holding the electrode too closely decreases welding voltage. This creates an erratic arc that may extinguish itself or cause the rod to freeze, as well as produces a weld bead with a high crown. Excessively long arcs (too much voltage) produce spatter, low deposition rates, undercuts and maybe porosity.
Many beginners weld with too long of an arc, so they produce rough beads with lots of spatter. A little practice will show you that a tight, controlled arc length improves bead appearance, creates a narrower bead and minimizes spatter.
Angle of travel: Stick welding in the flat, horizontal and overhead position uses a "drag" or "backhand" welding technique. Hold the rod perpendicular to the joint and tilt the top of the electrode in the direction of travel approximately 5 to 15 degrees. For welding vertical up, use a "push" or "forehand" technique and tilt the top of the rod 15 degrees away from the direction of travel.
Manipulation: Each welder manipulates or weaves the electrode in a unique style. Develop your own style by observing others, practicing and creating a method that produces good results for you. Note that on material 1/4 in. and thinner, weaving the rod typically creates a bead that is wider than necessary. In many instances, plain, straight-ahead travel works fine.
To create a wider bead on thicker material, manipulate the electrode from side to side creating a continuous series of partially overlapping circles, or in a "Z," semi-circle or stutter-step pattern. Limit side-to-side motion to 2-1/2 times the diameter of the electrode core. To cover a wider area, make multiple passes or "stringer beads."
When welding vertical up, focus on welding the sides of the joint and the middle will take care of itself. Pause slightly at the side to allow the far side of the bead to cool, the weld puddle to catch up, and to ensure solid "tie-in" to the sidewall. If your weld looks like fish scales, you moved forward too quickly and didn't hold long enough on the sides.
Speed of travel: The proper travel speed produces a weld bead with the desired contour (or "crown"), width and appearance. Adjust travel speed so that the arc stays within the leading one-third of the weld pool. Slow travel speeds produce a wide, convex bead with shallow penetration. Excessively high travel speeds also decrease penetration, create a narrower and/or highly crowned bead, and possibly undercuts.
A few last words of advice. Always remember that you need a good view of the weld puddle. Otherwise, you can't ensure you're welding in the joint, keeping the arc on the leading edge of the puddle and using the right amount of heat (you can actually see a puddle with too much heat roll out of the joint). For the best view, keep your head off to the side and out of the smoke so you can easily see the puddle.
Also remember that you learn through mistakes. There's no shame in grinding out bad welds. In fact, professional welders create perfect welds by recognizing imperfections, grinding them out and rewelding.
To get a great head start on your welding skills, contact Miller Electric for a Stick amperage calculator and an informative booklet on "Principles of Shielded Metal Arc Welding (SMAW). Both include diagrams on how to weave the rod, weld various joints, strike an arc, identify problems and make better welds. Call 1-800-426-4553 (800-4-A-MILLER).
Baxley Welding Service
Rembert, SC 29128
08-28-2007, 07:43 AM #14Senior Member
- Join Date
- Jun 2007
- Camden, SC
The above post refers ONLY to SMAW (stick) welding. My statements regarding GTAW (TIG) remain true: AC current is required for normal TIG welding on aluminum. With thick aluminum, DCEN may be used with an exotic gas blend of Argon, Helium, or other gas. I have attempted (and succeeded in limited capacity) with TIG welding aluminum with DC current using 100% Argon shielding gas, but I would NOT recommend it for a beginner nor in an application as critical as a boat, not because of looks, but because of penetration/strength. In addition, TIG'ing aluminum with DC current requires that the surface of the metal to be welded be EXCESSIVELY clean. Currently, the only folks I'm aware of who DC TIG aluminum are in the aerospace/space shuttle industry and their welding shops are sterile. I mean: S T E R I L E...like, wearing scrubs and masks and Operating Room style clothing/garments.....not like welding on a work boat at all.
Baxley Welding Service
Rembert, SC 29128