Gas or Tig?

[MrGrey]

Ok, I have been on a kick lately honing up my welding skills and I am accelerating pretty quickly with my stick skills. Luckily I get to practice at work for about 12 hours a week now. Stick welding is getting fun but I wanna try my hand at 4130 and was curious if people in our community prefer TIG welding or Gas welding the stuff. I assume Ernie gas welds his gear based on the bead, but could be wrong...anyone know?

[MikeBoyette]

Nope all done with a Tig.

[MrGrey]

Well I would be remissed if I didn't ask what kinda set up is used to properly TIG 4130? For instance what kinda electrode, filler, settings, etc work best.... I missed Jakes demo at 08 bensen days and was kinds pissed I missed it.

[MikeBoyette]

I am not sure. I will ask dad next time I talk to him. He only welds if he has to. Kosaka does most of the welding including your machine.

[Mike Schallmann]

Ive used all three; Gas Tig Mig -- some will argue but with my Miller aircraft welder I prefer Mig--

[Alan_Cheatham]

TIG is my welding method of choice, has been for years. A friend decided he didn't want to spend the money on a TIG rig when he started construction on a Littlewing and went with gas. After trying that for a short while he ended up buying the same TIG welder I have and hasn't looked back since.

Although it's not my main welder, I do have one of the little Harbor Freight inverter TIG machines that when it's on sale sells for around $200, and if modified with a foot controller for amperage control is capable of doing aircraft quality welds. It might make an acceptable low cost alternative for someone wanting to build a gyrocopter like a Dominator, one day I may get around to posting a review on it.
.

[RotoPlane]

I have used all four methods and like Alan, I prefer TIG because there is no weld splatter, less warp of material and better control of the bead, especially with thin 4130 sections. Of course, it is the only good way to weld AL.

For thicker walls I like MIG with flux-core wire, stick is okay for heavy sections and I never liked welding with acetylene torch.

[Racer]

I have all my work done with a TIG as well. Very clean welds and I can trust them as far as strength goes.

[Brent_Brown]

I use gas and TIG. I like gas for thin wall tubes.

[Lee Scatt]

Thanks all for your replies, I have just started to Tig weld and I am enjoying the control you have while running a bead. I have also experimented with Si/Br filler rod and made some really nice looking joints. How does brazing compare with welding overall?

[MrGrey]

To the guys with TIG welding 4130 experience,

What kinda starting settings would you use for say 5/8" tubing with a .035 wall. Gas flow?, electrode?, filler?, cup size?... lemme know.

[scottessex]

I posted this last week.....Welding tips and tricks. (http://www.weldingtipsandtricks.com/) Book mark it.

This guy is good, check out the razor blades, and soda cans welded together.

[Alan_Cheatham]

To the guys with TIG welding 4130 experience,

What kinda starting settings would you use for say 5/8" tubing with a .035 wall. Gas flow?, electrode?, filler?, cup size?... lemme know.

All that depends on several variables such as joint design, mass in the joint, access to the joint, whether you are using a gas lens or not, etc. so there is no one perfect answer.

I myself use a water cooled 20 size torch with rubber hoses, mainly for the flexibility as the power cable is much smaller than an air cooled torch, a gas lens with a cup size that will allow proper access to the joint be that flat or a cluster, flow around 12 to 15 cfh depending on the amount of electrode stick-out necessary to get to the joint. I prefer 1.5% Lanthanated electrodes sized according to the amount of current necessary to weld the joint be that a low mass "T" or high mass cluster, but usually 1/16".

For filler rod on 4130 I use ER80S-D2, typically spooled .045" MIG wire as I have converted an old sewing machine into a wire feeder. ER70S-6 is also acceptable and more readily available locally, especially in MIG wire and good for practicing.

Note that if you do research about what process and filler rod to use for aircraft welding 4130 you will never come up with a consensus of opinion as everyone has their own ideas as to what is best. These are the choices I have made based on many hours of research and personal welding experience.

[giro5]

All I know is tube and fabric airplanes were gas welded untill the monocoupe aluminum riveted frames came into vogue. It seems to me that MIG and TIG welds would leave any joint in stress as they do not heat up much of the weld area. All of my MIG welding has resulted in very weak joints that usually break. And I finally bit the bullet and spent a grand on a good MIller MIG unit. The welds can be pretty but they don't penetrate well. May be just my welding skills. I am pretty confident on my gas welds and that is the only thing I would do on a 4130 tube frame. Also from experience I can tell you forget the cheap walmart or harbor freight MIG or TIG stuff. If you are going to do it buy the best Miller or Lincoln equipment suficient to handle the thickness you are going to weld. The more I study it seem TIG is perferred over MIG just for the pentration issue but I would be worried about the stress left in the joint. RACER might not agree but if I were TIG welding I would use a torch to bring the whole joint up to at least a dull red and let it cool slowly in still air. The same as you are supposed to do with gas welding a joint.

[giro5]

One interesting book I bought recently was "WELDER'S HANDBOOK" A guide to Plasma cutting, Oxyacetyulene, Arc, Mig and Tig welding. By Richard Finch, SAE,AWS
It really just talks about the differences and pro's and con's of the various techniques. I think I bought it from LOWES hardware from about $20 bucks.

"Aircraft Welding" by L.S. Elzea circa 1942 from Lindsay Publications Inc. Is far and away the bible on gas welding aircraft 4130 tubing. I have bought a couple of videos from the EAA and the "Tinman" on gas welding and they don't have some of the techniques explained in the Elzea book. Like the direction you run the bead around the weld is important. Run it against the metal grain and the joint is more prone to fail at the edge of the weld.

[Alan_Cheatham]

See, what did I say, no consensus of opinion, everyone is an advocate of their own methods. MIG, TIG or Gas, if you can weld it together and it stays together then that's all that matters, there have been thousands of aircraft made with all these methods. Technique of the individual weldor has a lot to do with the quality of the weld so practice and do destructive testing on your joints until they prove themselves airworthy.

Case in point, a friend did the pictured gas welded joint and it looked good, even when beaten with a hammer but when flattened with a hydraulic press was brittle and crystallized. The TIG welded joint I did survived the crush test and every weld I have made with TIG that I have ground into showed bright shiny metal, so individual technique has a lot to do with weld integrity.
.

[Doug Riley]

There's a lot of opinion out there about whether TIG localizes the stresses that the part undergoes as it the bead solidifies and shrinks.

I use oxy-acet because that's what I have (Sears, late-70's model). I've had very good luck with it over many years, on both aircraft parts and trailers. It does cause more corrosion around the joint and tends to create a wider bead than TIG, if enough heat is used for good penetration. On the plus side, it allows you to pre-heat and post-heat the vicinity of the joint, which can prevent shrinkage cracking in very rigid assemblies.

Those who want to use TIG but worry about the locked-in stresses can go back over the assembly with a gas torch, heating the joints and adjacent components cherry-red. This will make the joint soft enough to yield to the stresses and relieve them.

You may have to un-warp everything when you're done.

I suppose one reason that tube-and-rag planes in the "classic" era were built using gas welding was that many rural locations didn't have electricity yet.

[scottessex]

This might be helpful to all y'all MIG welders. :)

MIG Welding 4130 Chrome-Moly
By Galen White, welding engineer, Miller Electric Mfg. Co.

Grade 4130 steel, while containing both chromium and molybdenum as strengthening agents, is considered a heat treatable low alloy (HTLA). Generally referred to as chrome-moly, this HTLA is used largely for aviation, racing and welded tube structure applications.

When welding 4130, preheating to 300°F is strongly recommended by the American Welding Society (AWS) to relieve stresses in the metal. When choosing a wire, most people opt for ER80S-D2 or ER70S-2. ER80S-D2 will provide the most weld strength. The ER70S-2 is easier to find and provides a strong weld, but you’ll be sacrificing some strength by choosing this filler metal over ER80S-D2. When it comes to shielding gas, 75/25 (Ar/CO2) is recommended for most applications and 98/2 (Ar/CO2) for anything over 3/16 in.

Wire Size-Amperage Range- WFS Range Relationships for Short Circuit Transfer on Steel
Wire Size Amperage
Range Wire Feed Speed
Range
.023" 30-90 100-400
.030" 40-145 90-340
.035" 50-180 80-380
.045" 75-250 70-270

Cleanliness is critical when welding 4130. Make sure that all mill scale and oils are removed using mild abrasives and/or acetone. When you strike an arc, keep your heat input low to reduce stresses in the metal.

Post-weld heat treatment of 4130 varies from one application to another. If ductility and toughness are your goal, post-weld heat treatment is recommended up to 1,200°F. If the material you are welding is thinner than .120 in., stress relief through heat treatment is not as critical.

WFS Rule of Thumb:
1 ampere for every .001 thickness
1/8" material=.125=125 Amperes
Wire Burn Off:
.023-3.5" wire/amp - 125 amps=437 IPM
.030 - 2" wire/amp - 125 amps=250 IPM
.035 - 1.6" wire/amp - 125 amps=200 IPM
.045 - 1" wire/amp - 125 amps=125 IPM

Welding 4130 is a lot like welding mild steel and is easy if you know how. These are just some of the reasons 4130 is considered so flexible and is used on everything from airplane engine mounts to bicycle frames.

[Alan_Cheatham]

I suppose one reason that tube-and-rag planes in the "classic" era were built using gas welding was that many rural locations didn't have electricity yet.

And the process wasn't invented until the early '40s.