Welding Tips and Tricks

This winter I am going to start building an experimental aircraft. The fuselage will be 4130 tubing, some of which will be as thin as .035. I am trying to find which TIG machine will best suit my needs and have narrowed it down to the Lincoln SW 200 and possibly the Everlast 210EXT. I'm leaning towards the Lincoln but am concerned a little about the harsh start up on some of this thinner tubing. Is this even a concern on thicknesses like .035, or are there techniques and work arounds that can be used? Lighting up on something else? Protecting the thinner tubing with the filler rod when lighting off? Focusing the arc on the thicker material first? Any ideas, tips or suggestions would be appreciated.

I can't imagine that the SW200 has such a high voltage >25amps on HF start that it would be a problem. You certainly can favor thicker material for any joint when initiating your arc start, but I suspect you'd be fine.

flylow188 wrote: I'm leaning towards the Lincoln but am concerned a little about the harsh start up on some of this thinner tubing.

I have a SW200 and the arc start current is reduced if you reduce the amperage setting on the machine. You're right, if it's set to 200A there's a pretty big flash when you strike an arc. But when I weld thinner material I usually set it around 75A and the start is much softer. I happened to run into the Lincoln repair guy at school one day and was talking to him about it. He couldn't remember where the change points were, but said if I reduce the current enough the arc start will soften up. He also explained that the machine has a separate circuit to start the arc, so when you first touch the foot pedal it doesn't matter how far you push it down for the first few10s of milliseconds, the machine takes control of starting the arc and stabilizing it. Once that happens control is passed back to the foot pedal.

I weld 20ga gate and corral panels all the time, that's about .037", and the machine works fine for that.

Thanks for the info. While my tubing isn't as thin as the razor blades in Jody's video on his review of the Lincoln, that start up that nipped the blades just had me a little concerned. I think the SW200 will suit my needs just fine.

Flylow,
Welcome! For years I was of the opinion that steel tube fuselages should be gas welded, and I've done my share of repairs on Cubs, Champs, T-Crafts and such using O/A. I recently picked up an Everlast 210EXP and have been enjoying practicing with it. I'm working on a Pietenpol now and need to make some fittings and an exhaust for it (A75 engine). In the near future, I hope to start a Monocoupe project, and I'm leaning to building the fuselage for that with the Everlast rather than the O/A. I think either the Lincoln or the Everlast would be good units for your purpose. I chose the Everlast for the low amp start off and the choice of wave forms in AC. When I got the machine, I upgraded to 25' superflex torch hoses. I've been practicing on 3/16 flat stock, so I've been using the 26 torch so far. Haven't even plugged in the 9 torch yet. I also got a 9 flex head torch, and the upgraded pedal with 25' chord. I can't imagine working around a fuselage with a short 12 or 14' torch and pedal. Recently I also made a 15' extension for my ground cable as that was only a 10', so now I can run that out to 25' as well.

@ flylow188 - Lincoln Electric SquareWave 200 is an excellent rig for welding ferrous and and non-ferrous materials. Definetly adaptable for 4130 tubing sizes common to the homebuilt aircraft (.030" -.050")

Context. Recently teamed with Lincoln Electric at EAA AirVenture 2017 (Oshkosh, WI) as a TIG Welding Instructor. We trained scores of aviation enthusiasts at hands-on workshops using the SW200. The lions' share of the students had limited/zero prior experience in any welding. They were able to accurately fuse metal, create sound joints, and in some cases produce nice stacked weld lines on 10ga lap joints in 304SS, 1018 steel, and 6061 Aluminum. We used 17-series torches exclusively, and personally had a quiver of various Tungsten "colors" (Purple, Red, Blue, Lime) in 3/32". All Tungsten colors performed well. As an aside, the machine's pulse capability for autogenous work on steel/stainless is also outstanding.

Should you decide to pursue the SquareWave 200 for 4130 work, you would do well to integrate a 9-series torch for tight space work and low amp applications. With a newer style hand ampetrol controller, to complement a standard foot pedal, you would have maximum agility.

This primer on welding from 4130 Chrome Moly Tubing - Top 10 Q&A - Lincoln Electric should help your understanding of welding CrMo.

Goes without saying, you'll want near-exacting and perfect fitups on all your tubing members before arclight. The smallest filler with the lowest injected heat into the 4130 is the crush. Score lengths of 4130 in your desired thickness and fuse acute/obtuse angles, "K" and "T" joints, etc to hone your skills before welding out your airframe.

Best fortune in your endeavors.

I like the features of the Everlast 210EXT and think I could put them to good use on my project, but I also like the simplicity of the SW 200 and since it should do the job I need to do I will probably go with it. I don't really care where a product is manufactured, but when spending this kind of money I feel more comfortable being able to walk into a store to buy it and if there is a problem take it back there. If both of these welders were sold in the same store with the same support, I'd probably choose the Everlast.

I would love the go to EAA Airventure someday but that is the busiest time of year at work for me. While working I have to listen to all the pilots flying there because many use the same frequency that we use. Someday I'll get to go.

I already picked up a scrap pack of 4130 from Aircraft Spruce to start practicing. I do have my A&P ticket but welding isn't a skill they test on so I will need to practice a lot before the real thing. Anytime we need welding done at work we have a professional do it. Now I just need to decide on a good hole saw tubing notcher or just go with templates and grind them out.

I went to Oshkosh twice when I still had my Howard. It was fun, but way too many people. I go to Blakesburg to the Antique fly in there. Less people, not commercial at all, a lot more fun.

Got my A&P back in the '70s when you still had to learn welding. Glad I at least got that background.


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flylow188 wrote: If both of these welders were sold in the same store with the same support, I'd probably choose the Everlast.

Actually Home Depot sells both Everlast and Lincoln welders, not sure which models are available but you would be covered by the HD return policy

flylow188 wrote:Now I just need to decide on a good hole saw tubing notcher or just go with templates and grind them out.

I have this unit and have been very happy with it for Tube notching of motorcycle frames, bike frames, and other "stuff"
https://www.jd2.com/p-63-notchmaster.aspx

cj737 wrote:

flylow188 wrote:Now I just need to decide on a good hole saw tubing notcher or just go with templates and grind them out.

I have this unit and have been very happy with it for Tube notching of motorcycle frames, bike frames, and other "stuff"
https://www.jd2.com/p-63-notchmaster.aspx

That notcher won't work for the application at hand. Smallest it goes is 3/4, and for a homebuilts airplane, that would be about the biggest size, most of the tubes will be 1/2 or 5/8. The Joint Jigger at aircraft Spruce would work, as would harbor freight.

Personally, I don't like tube notchers. There are a couple tube coping programs on the net that will print out the profile, you input the OD, wall, and angle. Cut it out, wrap it around the ind of the tube and mark, then cut it out on a grinder, or tin snips, or whatever. Another option if you have a large is to chuck an end mill the size of the butting tube, and set up a vice to the angle you need and feed the cross slide with the tube in the vice (my preferred method).

Depending on what airplane you are building, you might want to check if VR3 already has it modeled. They laser cut every tube so it literally falls into place. Costs a little extra, but everything fits the first time! They have a number of designs already modeled. You will still need to build an assembly jig.


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