Hatz Biplane Association

I'm at an impasse and I need recommendations and experiences of those who have gone before.

I am trying to decide if I want to go TIG or gas for welding. I have no experience with either, except for giving gas welding a very short try at OSH. I did not impress myself I might add.

I thought I was going to go gas, but when I went to my local Airgas store, The salesman (yeah, I know his job is to SELL stuff) looked at me like I was from the stone age when I inquired about the cost of O2 and Oxy tanks. Said practically nobody ever asks for it, and that most are going TIG or MIG. He then proceeded to show me a Miller Diversion 180 unit, to the tune of just over $2000.00 for what I would need etc.

After spending way too much time online researching the pros and cons of Gas vs TIG, I feel like I am no closer to a decision than when I started.

Here are my concerns, and I would appreciate any input folks can give me:

1) Normalizing 4130 tube. Is it required after a TIG weld in .035 4130 tube? Some say yes, some say no. Last thing I want is a fracture just past the HAZ.
2) Do those that use TIG find that they need a torch for other purposes, such as bending metal/tube, tweaking warped areas after a weld?
3) learning curve. From what I have read, learning TIG is fairly easy/quick vs gas.
4) Should I spring for a TIG unit that has a pulse feature? More $, but is it really necessary? Its my understanding that you can fill gaps, to some degree, better with a pulse unit.

5) Getting into tight places. Gas is more adaptable here, but I see that there are tricks/ equipment that allow TIG to do just as well....Gas lens, smaller tip/ceramic, extending the tungsten.

6) Cost. At least 2x more expensive to get set up than gas, but if TIG is indeed easier, more consistent, more precise, then I am willing to go for it.

Sure would appreciate any input. My head is spinning right about now.

Hi Jeff,

Since I'm not welding, can't answer your questions, but I'll throw this out in case it helps in the bigger picture.

I was just as confused as you are now. I decided to go with gas after reading all the discussion here:

viewtopic.php?f=8&t=374

I think I read somewhere that there's no escape from gas...that even with TIG you'd still need a gas set-up for certain tasks.

Highlights from Bi-plane forum discussion:

*******
Gas: Cheap to get into, doubles as a cutter, easiest to learn, safe, effective. Very portable, no need for electrical hook-up, braze, solder, big heat affected zone requires minimal stress relief (If any)


TIG: more precise heat control, cleaner and nicer looking results, more precise control over thin materials. If AC/DC--can weld just about ANY metal with ease, easier to weld dissimilar metal thicknesses, can very the "heat" as the bead progresses, great penetration in thicker metals, since the torch is not "hot" when not in use---easier to maneuver around in a tubular structure when finish welding.
******

You can get more confusion here: http://www.homebuiltairplanes.com/forum ... -sort.html

As fas as the cost of tanks, Tractor Supply sells and fills the Thoroughbred models. I think they charge about $20 if you bring some other brand in. Anyway, something that holds about 40 to 60 cubic feet should be good enough. At welding class, the Oxygen was a 60 and the Acetylene was a 40. At Northern Tool Supply supply, you'll pay about $210 for a 40CU O2, and $190 for a 40CU acetylene. Check their stuff here: http://www.northerntool.com/shop/tools/ ... rs-caddies

Tractor supply wanted just under $1K for the largest size set-up....which I don't need. An hours burn time is good enough (for me) and just go refill 'em. Compared to Northern Tool, prices at TSC look better.

Might want to check with your insurance company about coverage with those in the house. As I understand, welding with anything can be considered an increased fire hazard and may affect your premium. I haven't call my insurer yet as I don't even have regulators (on back-order), so can't tell you my experience with that; in any event, just part of the expense of building.

By the way, the EAA instructor never mentioned stress relieving (this was gas welding class). What he did mention, more than once, was to NOT just quickly take the flame away, but to be gradual and let the weld cool slowly. He also stressed to NOT spend an extended time at one spot because that would affect the characteristics of the metal in that area (in a bad way). Also, should a piece bend, applying heat on the other side would "undo" the bend and you'd have a straight tube again. He also recommended not going cheap on the equipment. I can't wait to try all this out.

I spent an incredible amount of time reading everything I could (books and on-line), watched DVD's and EAA workshop videos (on-line), researched the equipment/read reviews and made my decision...gas and purchased this starter kit: https://www.tinmantech.com/html/kits_4130.php#1 with everything else from ACS: Smith regulators, tip cleaners, flint lighter, extra flints, silver pencils and welding apron. Still need a helmet or goggles.

I hope this helps.

I can't answer all your questions, but I'll throw in my $.02. I'm gas welding so my comments will be from that perspective.

1. Can't say. There is a school of thought that below a certain wall thickness (where a lot of our welding is) stress relieving the joint is not necessary. There's a good FAQ on Kent White's Tin Man site. Granted, he's biased towards gas welding, but he's also a world-class craftsman and has worked on several airplanes so I give a little more weight to his opinions... but that's just me. https://www.tinmantech.com/html/faq_welding.php

2. You WILL need a torch for other things. You'll need to heat & bend a number of things including the fuselage sides, torque tube pieces, rudder/elevator, seats (maybe), etc. You may not use a torch on all those things, but you will use it on some.

3. I don't think the learning curve would be all that different. Each has it's own techniques and regardless of which you choose you won't be too impressed with yourself when you first start out.

4. No idea.

5. Tig has been used on enough airplanes that I'm sure tips/trick/techniques exist to deal with most of these scenarios. Don't know that it matters all that much.

6. My experience (a few years ago) was that a good TIG setup was 3-4 times more expensive that Gas.

DON'T let the guys at Airgas change your decision, whatever it may be. Those guys have no clue what it means to be welding thin wall 4130. My local Airgas dealer was cool about it, but that's not everyone. You're doing the right thing by talking to builders. Get opinions from those who've been there and make an informed decision.

I can't imaging attacking this project without a gas unit. If I had a TIG unit I would probably use it for the fuselage in place of gas but gas is so handy and always ready to go. I have been looking at the TIG welders and will probably have one at some point but for just regular around the house stuff, gas is great. I have the same torch that John has, the Medco Midget, and the other torches never come out of the drawer. I am not a big fan of the small hose that I got with it though. It just doesn't really seem at home on the floor, I am using it and it works well, but I am always worried about stepping on it or cutting it with something.
Get them both, its only money and after all, we must be rich, we're building a plane.
PS, it's harder to set yourself on fire with a TIG unit.

Well shoot, Ed.... Where's the fun if I don't flame myself?! Good point!

I'm starting to lean back toward gas. Sounds like I will need it for various tasks anyway. I have a friend that's a wiz with gas, so there is help out there for me. Just gotta make sure he'll douse any flames for me.....

There's no question that if you're only going to have one type of welding set-up, it's got to be gas. In a tube a fabric airplane, welding the clusters is only part of it. There's an amazing amount of forming and bending required on things like the strut ends, finger straps, wire lugs, etc. All stuff that just can't be done without a gas torch.
I used gas entirely during the construction of NX1279 because it's challenging and fun, but in my opinion, it's far easier using TIG. The most important 3 things are practice, practice, practice. There are some areas in the tail feathers where you're trying to weld very thin channel sections to heavier tubing. Those areas are especially challenging with gas.
Mark