Mig or Tig. I need help

[Mr.Gadget]

I have a 20ft commercial jon boat that has some broken weldes that needs repair,and needs some other custom fabricating.the boat is 3/8 inch thick.I only have a stick welder now.I need to buy a aluminum welder.should i get a miller mig.or the syncrowave 200.or 250.

[BWS29128]

have a 20ft commercial jon boat that has some broken weldes that needs repair,and needs some other custom fabricating.the boat is 3/8 inch thick.I only have a stick welder now.I need to buy a aluminum welder.should i get a miller mig.or the syncrowave 200.or 250.

This is going to sound stupid, I know, but are you wanting something to repair your boat with? At 3/8" thick, it sounds more like a custom work barge instead of a "jon boat". At 3/8" thick, assuming your boat is something other than 2000-series or 7000-series aluminum, and also coupled with the fact that you appear to have some experience with SMAW (Stick) welding, I'd just go spend $20 on a pack of Hobart418 Stick rods and weld your boat together using that. That's your cheapest alternative and quickest alternative and it's not like you're worried what your welds will look like on a work boat.

After that, I'd suggest going with a Millermatic 212 with 3035 spoolgun option (or an HTP or an ESAB-----see my other thread about ESAB, HTP, and Miller) to keep your initial costs down.

If you WANT a TIG-rig, I'd suggest something other than the Synchro series stuff for repairing your work boat...maybe the Dynasty 200, and the 200DX at that if you can afford it. You're going to need something a little more portable for getting your machine down to the boat, repositioning it, and getting it back up the dock/pier again.

I'm probably going to get clobbered by someone for suggesting something other than a Synchro, but that's my .50 cents for what it's worth.

[Aerometalworker]

This is going to sound stupid, I know, but are you wanting something to repair your boat with? At 3/8" thick, it sounds more like a custom work barge instead of a "jon boat". At 3/8" thick, assuming your boat is something other than 2000-series or 7000-series aluminum, and also coupled with the fact that you appear to have some experience with SMAW (Stick) welding, I'd just go spend $20 on a pack of Hobart418 Stick rods and weld your boat together using that. That's your cheapest alternative and quickest alternative and it's not like you're worried what your welds will look like on a work boat.

After that, I'd suggest going with a Millermatic 212 with 3035 spoolgun option (or an HTP or an ESAB-----see my other thread about ESAB, HTP, and Miller) to keep your initial costs down.

If you WANT a TIG-rig, I'd suggest something other than the Synchro series stuff for repairing your work boat...maybe the Dynasty 200, and the 200DX at that if you can afford it. You're going to need something a little more portable for getting your machine down to the boat, repositioning it, and getting it back up the dock/pier again.

I'm probably going to get clobbered by someone for suggesting something other than a Synchro, but that's my .50 cents for what it's worth.

I aggree!
Arc welding .375" aluminum shouldnt be that bad at all. My guess would be either 3XXX or 5XXX series Aluminum, either one would be fine. Again if you want to buy another piece of equipment, a Mig/Spoolgun setup might be the best option for that material. I have a 200 dynasty and I would also reccomend that as the TIG source if you must go that route.

I have to ask though, what are your experienced with as far as process? By experienced I dont mean " seen it done" but actualy proficient at it.

-Aaron

[jwsrep]

If your looking to just weld up your boat you could see if your LWS has rental equipment that you can rent. Should be tons cheaper than buying. My guess is 5052. That is the aluminum they use to make pontoon boats I believe. 3/8" sounds kind of heavy for an aluminum boat, but you did say commercial craft didn't you?

To answer your question, I would recommend MIG/push-pull or spoolgun. 5356 wire 3/64" diameter with pure argon gas.

[BWS29128]

If your looking to just weld up your boat you could see if your LWS has rental equipment that you can rent. Should be tons cheaper than buying. My guess is 5052. That is the aluminum they use to make pontoon boats I believe. 3/8" sounds kind of heavy for an aluminum boat, but you did say commercial craft didn't you?

To answer your question, I would recommend MIG/push-pull or spoolgun. 5356 wire 3/64" diameter with pure argon gas.

Rich, I agree with you on everything except maybe the 3/64"...he mentioned ribs/spars didn't he? I wouldn't think he'd need something as big as 3/64" unless he was repairing holes in the hull would he? I don't know...maybe I'm confused...I thought 3/64" wire was mondo-monster wire for giant projects....no? Doesn't 3/64" require all sorts of special liners and tips and adapters? Oh WAIT A MINUTE..........you want him to buy from YOU, don't you?!?!?!?! ROFL!!

Also, if he's got the money and that's ALL he's planning on doing (aluminum), then the push/pull is probably the way to go....larger spools of wire, less time switching over, etc etc. Unless he's planning on anodizing, if he uses a P/P or SG, 4043 would be fine, right? And a little less expensive? Oops...there you go again!!! Really, those 4043 beads'll come out looking really shiny and nice.....

[jwsrep]

Oh WAIT A MINUTE..........you want him to buy from YOU, don't you?!?!?!?! ROFL!!:

Clint,
3/64" wire is not big at all. Its .047" diameter. He did mention that he was working on 3/8" thick aluminum. I must have missed where he said he was working on ribs/spars. I have customers that use 3/64" wire on 5/16" aluminum and up.
The reason I recommend 5356 is because it has better as-welded strength than 4043 does on 5052 base material.

[fun4now]

welcome,
i think jwsrep made a great point about renting. if its just to fix it up this time and be done with it, it would be cheaper and give you a chance to try it before you buy it. the TIG is going to be very slow but look nicer but as they said if its not going to be seen or its a work boat MIG would get the job done faster and not look bad at all after some practice.

[6010]

This is just something to think about. I don’t have the knowledge or experience that most of these fellows do as far as welding is concerned, so take this advice as given by a non expert. You didn’t mention anything about using the welder for anything beyond repairing the boat and you did say you had experience stick welding. For that reason, the stick welding repair Clint mentioned sounds like the most viable option for you as far as economics is concerned. That 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 – 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 – and it looks strong.

Now the ribs, if they are thin, sound more like a job for a Mig rig. And I say Mig because a low end Mig rig is a lot cheaper than a low end Tig rig. Plus something like the Miller 180 or Hobart 187 you have seen mentioned, or maybe something smaller would be easier to handle. I have the Synocrowave 200 and I think it weighs over two hundred pounds without the bottle. In my prime I don’t think I could have lifted it into the back of the truck by myself. Ok, maybe in my prime I could have, but it would have taken both hands.

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 can’t remember. Now they didn’t have the luxury of a foot pedal, but they did a good job of it just the same.

[phaxtris]

stick or rent a mig machine ( spool gun/push pull pref, more mobility )

[BWS29128]

Forget What I Said: Rich Is Right On All Counts!!

Clint,
3/64" wire is not big at all. Its .047" diameter. He did mention that he was working on 3/8" thick aluminum. I must have missed where he said he was working on ribs/spars. I have customers that use 3/64" wire on 5/16" aluminum and up.
The reason I recommend 5356 is because it has better as-welded strength than 4043 does on 5052 base material.

Rich, You're right on all counts: I was thinking 3/64" was REALLY big...not sure why; lack of experience with that size I suppose (oh, and the fact that I absolutely suck when it comes to converting decimals and fractions might have something to do with it as well...). Again: absolutely correct on as-welded strengths too...a very important thing to look at when dealing with a work boat. Even if his boat ends up being 3003, 3004, or 5056 (or heck, even 8086!) then the 5356 will be a better option.

Hope I didn't confuse you unnecessarily, Mr. Gadget...forget what I said and go with Rich on this one.

[BWS29128]

That 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 – 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 – 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 can’t remember. Now they didn’t 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).

Again, hope I didn't screw anything up too badly. ~Clint

[6010]

Clint,

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 don’t 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 …. And if I am not, reread the first sentence.

I am still looking forward to meeting you sometime in Hartsville.

[BWS29128]

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:

http://www.millerwelds.com/education/articles/articles16.html

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.

Remember CLAMS

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).

[BWS29128]

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.