Need assistance in determining best welding option. What did most builders do?

[Guy Delumeau]

Just starting and we need to decide what kind of welding to use. Cannot find a consensus. Analysis for best option goes back and forth. What did most builders do here? EAA seems to use gas tig. Don't know the plus and minus of gas or gasless tig. We were thinking of gasless tig or gasless mig but we found a very experienced gas mig welder that would work with us. Our welder worked on trucks that (mostly) did not fly though. Without him, we would need to learn if we did not choose gas mig.

Trying to get in the right direction before we start welding. Appreciate any direction or warnings.
Thanks

[mswain]

Guy.....you are not going to get consensus on your question. Bob the designer prefers Oxy/Acetylene. There are many builders who successfully TIG, like me. Choose the process you are most comfortable with and build, it will work either way.

[Island_Moose]

I can save you a lot of time. You can stroll through the internet for days and never find consensus (Ive just done it). Oxy/Acet 'gas welding' or TIG welding (TIG uses argon) are the 2 options. I suppose some people will MIG weld but there's reasonable agreement that this is less than ideal.

I have done a lot of gas welding, and you need a gas rig to bend some steel parts on a Bearhawk. Gas welding has a much lower initial purchase price as well. All of this means I should gas weld my fuselage.

But if I can save the money up, I'm probably going to TIG weld it for 2 reasons...one is that I'm interested in TIG welding and the precision of playing with dials and buttons, the other is that I prefer the 'stack of dimes' look of the welds versus the slightly cave-man look of a gas weld (particularly on welded fittings).

Don't stress over heat-treating either...there is zero consensus on that topic.

So I'll end up with both in the shop...along with my MIG for fixing the tractor.

[alaskabearhawk]

MIG welding, using either shielding gas or flux core wire, is not an accepted method for aircraft construction. Either O/A welding using RG45 (preferred) or RG60 filler wire or TIG with shielding gas using ER70S2 or ER70S6 filler wire are the two processes that are pretty much the standard for aircraft construction. I use mainly TIG, but have used O/A in some areas. If you don't know, get some training! A local community college or VoTec may offer welding classes...and tell them what you plan on doing. My welding instructor tailored my training to what I was doing and tested my samples, giving me tremendous confidence. And to drive the point home, practice, practice and practice some more. It's not hard, just get some good instruction. This may help: https://www.youtube.com/watch?v=ZEA-g8sMynY

[whee]

There is no consensus so you’ll need to make your own decision. If you don’t want to read through the old threads and other information then I’d suggest defaulting to what Bob specifies which is O/A welding using RG60 rod.

Essentially every EAB kit manufacturer tube and rag airplanes uses mig welding. The only one that I know of that doesn’t is Bearhawk Aircraft and they use O/A. Maule and American Champion also use mig. I personally would not build my airplane using mig.

I used TIG on my airplane. TIG is fine but it does result in a more brittle joint. Realistically though, the joints will not see loads that would cause them to fail. I would have preferred my airframe be O/A welded just for piece of mind.

A good O/A welding can stack dimes just like a good TIG welder. The weld looks dirtier due to a larger HAZ but once blasted and pained then look the same. Plus, O/A welding is much more tolerant of mistakes and/or poor workmanship.

[alaskabearhawk]

I don't know anyone or heard of any EAB using MIG. Everything I have read discourages it with the exception of tack weldong. I guess it's possible though. Maule does, but the weldors are highly trained and do it under controlled conditions. As to TIG being more brittle, I welded a T sample, 4130 3/4in dia and .035 wall. I put it in a vice and beat the snot out of the welded on piece, back and forth with a 5lb hand sledge. I bent it every way it could bend but the weld never broke or showed signs of cracking. YMMV.

[spinningwrench]

RANS, American Champion, Maule all MIG weld airframes with the exception of really tiny fittings or extremely critical welds. MIG is fine but requires a pulsed approach to avoid too large a heat affected zone. That technique is best learned from someone who welds airframes for a living. For a novice I would avoid MIG. Otherwise oxy/acetylene or TIG are fine. TIG is pretty much the standard of the aerospace and race car industry now for its small heated affected zone and quality of the weld. Look at Lincoln Electrics YouTube videos on TIG as they have some specific to airframes. Likely you will end up owning both. Either way I highly recommend taking a class from the EAA academy they have excellent instructors in either type of welding.

[whee]

I’ve stood I the hangars where the fuselages are built for two different kit manufacturers and witnessed the fuselages being mig welded. I also called several others and asked what their processes was. Every time it was mig. This was back before I had decided to build a BH and was trying to decide which kit I wanted to build.

There is a blurb in an old Beartracks where a guy welded a sample and broke it off in the HAZ by bending it back and forth. I can’t remember how many time he had bend it but it was very few. I did the same test and mine broke pretty quick. It doesn’t break the weld it breaks in the HAZ. Heating the HAZ with a gas torch after welding helps reduce the brittleness of the HAZ. Post heating used to be the standard for TIG on thin wall 4130 but it has since been determined that it isn’t necessary. There is no failure mode on an airplane or car chassis that will bend a welded joint back and forth till it breaks. I did another test with O/A and never could get it to break.

Guy, as you can see there will never be a consensus. AKBH and I have gone the rounds on this several times before with many other builders sharing their opinions too. Search for those threads, study the EAA material, and look for other reliable resources. AKBH has a cool YouTube video where he puts a welded sample in a tensile test machine and pulls it till it breaks.

There is a lot that goes into welding a safe and reliable airframe so do the proper homework before striking that first arc.

[rodsmith]

The majority of my project is TIG welded, I think it is great for some of the smaller parts where you need to be precise, and produces less dimensional distortion. My TIG welds look much better than my gas welds, but that doesn't mean they are better/stronger. If starting over I would go with mostly gas. MIG sure would be convenient for tack welds and probably OK if totally remelted with TIG or gas, but I didn't have one.

[Bcone1381]

If you have some time, start reading the thread below on about page three and keep going until at least post #111. Then get in touch with Dave and others to find out "Dos and Don'ts" Dave has amazing resiliency and stamina. I really look up to you all who scratch build. You guys are a group of humble pillars of the amateur built industry!! Quietly doing what no common man would conceive in ones imagination.

https://bearhawkforums.com/forum/bearhawk-lsa-plans-build/26929-davzlsa-progress/page8

[davzLSA]

Its not humility Brooks just dogged determination to get an airplane built and not kill anyone along the way.

[Guy Delumeau]

Okay. Got it. Throwing away my mig. Going O/A. Just starting out but encouraged by the support in the forum. Feel much more confident in our direction. Thanks.

[davzLSA]

Unless you are an accomplished welder I recommend you just buy a factory welded fuselage kit. It will save you tons of time and money.

[BTAZ]

For my LSA, I used my TIG for the aluminum tanks and for some of the heavy welding in the landing gear and shocks.

The rest I gas welded. Many years ago I took a one semester welding class and spent the whole semester gas welding. That got me the basics but it took a lot of practice and actual welding on the airplane to get up to speed again.

I found it much easier to gas weld when out of position, reaching across/through/around tubes in the fuselage, etc. than TIG with the helmet and foot pedal

I would recommend buying a few 8' sticks of typical 4130(.035 or so wall, 5/8 or so OD) and not the "welding practice drops" as the latter tend to be much thicker wall thickness.

Make sure things are clean.

Make sure you see the filler melt into the metal and not just sit on top.

Make sure the flame is set correctly to avoid adding carbon to the weld.

Quiet puddle good, sparking puddle bad.

Cool slowly.

Appearance doesn't matter that much if you are confident the above was followed.

By the time you are done, you will be well along the way to the "appearance" criteria.

But it isn't all that difficult and a great learning experience if that is why you are building an airplane.

[schu]

Lots of airplanes are mig welded these days, though they are welded by expert welders that know exactly what they are doing. The carbon cub stuff is all mig, which surprised me. So, it's possible, but it takes expert level of proficiency. Everything works if you are an expert, but if you aren't then gas welding is the easiest to get right.

I have a tig and know how to use it, but if I was building the engine mount, I'd use a gas setup.

[Sir Newton]

Oxy acetylene welding & TIG are both easy process that an inexperienced operator can easily tell if he has screwed up. Meaning final weld inspection is very straightforward.
MIG, requires a little bit more experienced and training the operator should understand what cold lap is. Weld inspection should be done by somebody that is certified in the welding trade.
Being a professional in this field I would advise against mig unless you have a very good operator!

[svyolo]

I learned to TIG during my QB build because I wanted to. I am still not good enough to do primary structure or primary flight controls, but I am getting there. Worst case, if I was going to build a fuselage myself, would be to tack it together and hire out the rest of the welding. I will probably try out OA welding in a few months.

Mig is pretty easy.