Not THAT question AGAIN!

Sorry guys but I have been reading everything about this subject thats available on the internet and I am more uncertain now than I was when I started out. The familiar and apparently hotly debated question is...

Which is 'best' for welding 4130 Chro-Mo? TIG, MIG or Gas?!!!

This question is so common and thoroughly debated to the point of confusion it's almost ridiculous. 'Experts' of each method insist on theirs as the 'only' method to ever use. 'Amatures' new to welding just want to know which method to become proficiant at for the 'best' and 'safest' weld and seem to be often told to use O/A gas first but later start using TIG, instead of just learning to TIG in the first place. 'Old timers' who have welded for a living insist on the tried and true O/A gas yet newer (last 10yrs) welders insist TIG is the bugs ear for 4130 and gas is old school. I have read that long time and trusted aircraft manufactures have been using the 'never use it on 4130' MIG method to weld their airframes for decades without a problem while other manufacturers use MIG 'primarily' and TIG only for 'critical' areas. Well respected organizations and builders like Tony Bingelis, the 'Tin Man', and the EAA among others all have their own seperate opinions on the the same subject. Even 'normalizing' or 'stress relieving' the joints aftrerward is debated, some always do, some never have without a problem. It's all VERY confusing.

I plan on building an aircraft using 4130 Chro-Mo for the airframe starting some time next year and I want to start getting proficiant (read- airworthy weld joints) at welding before then. It's my butt I'm risking, so, knowing what metal I'm going to have to weld together I would like to take the right classes (Sportair) and purchase the right equipment and start practicing (along with pounding a thousand rivets till I get that right too).

I know if I just go ahead and sign up for a class whether its TIG or Gas, by the end of it the instructor will probably convince (brainwash) me and the rest of the class that that method is the 'only' one to use.

Can we come to a general (hopefully specific) consensus as to which method to use to weld 4130 that I and the rest of those new to welding should invest their time and money to start to learn? I dont care which method looks the nicest (its gonna be skinned over anyway) or which method is the easiest to learn (I got plenty of time to learn), or which is cheapest (the price of my life is'nt cheap). I want the safest, strongest, 'best' weld for 4130! Maybe I need to take a poll or something I dont know. I'm about to flip a coin! Thanks


Mike

 

which weld

Flip the coin . . . .
If you are proficient and do good work they are all good. I doubt very much that one is stronger than the other. You melt two pieces of metal, insert some filler rod and let it harden. The weakest point is going to be right at the edge of the weld where the tube didn't quite melt but got hot enough to sag/stretch/become slightly thinner. No matter which method you use to weld you will always have this "grey" area that will be weaker than the actual weld so - it does not make any difference. Just do what you do well with good penetraqtion of the base metal.

 

I work as a certified aircraft welder, we TIG everything. Gas has been around forever and if you look at any old tube airframes those guys were artists with a torch. Either is fine.
10 years ago I went to look at a popular kitplane that was for sale. The owner hadnt done very much on it at all. It was a MIG welded tube frame. Done by the kit manfactuer. I didnt see one weld on it that would pass a decent QC inspection. Just because somebody does it dont mean its right.

 

Thanks for the replies.

Flyguy, would you say then that since it doesn't matter which one to use, try all three to see which one your better at then go with it?

Pilot103, sorry, I'm just trying to pin this down. Question, If Gas has been around forever, works just as well, doesn't require normalizing and is cheaper, why TIG?

Thanks

 

Tig welding is much faster and covers a wider range of metals. You cant gas weld titanium or many other alloys. I will add that I am also certified to MIG weld pressure vessels and pipe.

 

I feel your pain, Bro. I'm no expert; but, like you I plan to build a rag-n-toob-fuse-tin-wing plane. I will order my torch from the tinman and stress relieve the joints. Simple, cheeep, eezy, proven. hope this helps.

CAB
Bearhawk#862

 

Thanks CAB. I've attended several of the Tinmans forums the past few AirVentures and he is a very intellegent and talented guy and amazing to watch. It's hard to disagree with his philosophy of gas only welding, especially when you see what he accomplishes with it. The only thing about that is I know the guy has been using a torch for many, many years, he should be good by now. But what about the novice new guy? How long does it take to learn to make consistantly safe welds on 4130 using gas as opposed to the others? Sure, if I plan on firing up a torch for several years before I begin building my airframe then I wouldn't worry about it whether its Gas, TIG or MIG for that matter, but I dont want to wait that long. In that respect, if you practice over and over again for long enough, then yes, I'm sure any of those methods would eventually be fine.

I just want to be sure that what I commit to as a novice welder is #1 correct for 4130 and #2 not going to take me until my name is Tinman in order for me to make a good, safe, solid weld.

 

OK, technical crap aside:

Frankly, Gas and TIG use the same method. You dab an electrode with your left hand at a weld pool created with your right hand.
The difference is that the weld pool is created with gas in one method and an electrical spark in TIG.

Pro's and cons of oxy acetylene:

Easy to learn,
Slow,
Oxydation is high,
Hot work,
Not reccomended for confined spaces,
Very low initial cost

Pro's and cons of TIG:

Your tungsten tip needs to be less than half an inch from the work. If you touch the work, you ruin the tip, and probably leave some tungsten in your weld. You'll need to re-grind your tip. If you're new to TIG, you'll do this at least every 10 minutes.

Heats the metal fast and in a small area - reduces the risk of distortion (not an issue with butt welding tubes)

Job gets hot fast, then REALLY hot soon after that - you need to compensate by welding faster as you go, or using a variable foot pedal.

Great for fiddly and confined work

Small torch.

Riggers gloves are adequate protection, so better dexterity.

Welds any metal.

Arc can be troublesome to control in accute angles

High initial cost - almost 10 times dearer than oxy.

If you can't roll your left thumb along your left forefinger at three inches per minute while you wrist makes a dabbing motion every second, while moving your left arm at half an inch per second to the left, six inches from your desk, while your right arm moves in the same direction with a pencil a quater of an inch from your desk while your foot slowly rises from the floor, TIG may not be for you.

Oxy is the same but in slow motion and you can ignore the foot rising (amp controller pedal)

:gig: :gig:

Which do I prefer? TIG! Which would give a better weld quality for a novice - Gas!

 

Good points, thanks Peter.

 

Gas welding

I more or less learned to gas weld by myself and it was somewhat frustrating at first. If you have someone teaching you, and you have a modicum of talent for it, it is all down to practice. In Britain we had to pass the same tests professionals had to when working on airframes for homebuilts and my welds passed all the tests, including x-ray and tensile tests, not just visual. So, yes gas welding can be picked up by the amateur fairly easily. Incidentally, I used commercial mild steel filler rod with my test pieces; with the correct technique the weld will always break outside the fillet, so using a high strength rod is really not necessary for 95% of your joints.

 

Gas welding

I more or less learned to gas weld by myself and it was somewhat frustrating at first. If you have someone teaching you, and you have a modicum of talent for it, it is all down to practice. In Britain we had to pass the same tests professionals had to when working on airframes for homebuilts and my welds passed all the tests, including x-ray and tensile tests, not just visual. So, yes gas welding can be picked up by the amateur fairly easily. Incidentally, I used commercial mild steel filler rod with my test pieces; with the correct technique the weld will always break outside the fillet, so using a high strength rod is really not necessary for 95% of your joints.

 

Hi and good luck!

I used to teach welding. I would dearly love to have a TIG machine but can't right now on my budget.

Some of the new machines have neat features that will automatically ramp the current up and down as you weld, and do some other other stuff to help you weld. You don't really need a high amperage TIG but you will at times need one that will go to very low amps. A foot control is a must as far as I am concerned. Buy a good machine and it will last for many years.

When I bought my old Pitts Project I needed to do a few more things as far as welding so I bought a cheap torch kit from Harbor Freight $100 and bought some tanks (about $300). It isn't fancy at all but it will weld just fine. Tank refills are about $50 for both and that is after a lot of welding. It is a skill you can learn and some instruction will get you started. Then just practice and pretty soon you can make nice welds too.

The nice thing about oxy-acetylene is, well a couple of things; you can take it with you to where the welding needs to be done, no electricity or generator needed, you can use it for all sorts of general repairs too. You can heat or cut off all sorts of things too. And learning how to torch weld will transfer to using a TIG very nicely.

You can build a very nice steel tube airframe with with oxy-acetylene. Even if you have a TIG machine, you will still find there are times an oxy-acetylene torch to heat something is what you need.

you can be making good welds 0n 4130 in a couple of weekends of practice assuming you have had someone show you the safety basics and what making a good weld looks like. There are some safety things you need to learn (you can read about them in a book) like keeping the acetylene pressure below 15psi, keeping the acetylene bottle upright, (it is filled with acetone to absorb the gas and prevent explosion), open the bottle valves slowly, keep caps on the bottles when you transport them, and a couple other things. Once you learn to make good welds, it is really a lot of fun too.


Good luck!
Wally

 

TIG Machine

I'll be starting my next plane very soon, a Tailwind W-10

I'm pricing a Miller Syncrowave 250 DX w/runner... The best price that I've found was online at Welders Plus for $3750.00 ( plus tax )
I'm gonna talk to the guys that supply us where I work and see if they will match the price....

This is a TOP OF THE LINE MACHINE.....But it will handle ANYTHING

I could get a real good machine for about $2,500 , but I really like the Syncrowave 250 DX ( we use them at work )


The ONLY thing that I "Don't" like about it....it's a little BIG.

and Foot pedals.......suck

Ever since I worked as a "Code Welder" I got used to the switch at the torch....and the syncrowave has the option to "start Hot" then go to a set welding temp.....also instead of clicking on and off at the end to avoid crater crack , it has a feature that ( besides post flow) that will ramp down the heat when you click off....


Oh yeah...
Gotta Fly...
Mike in MN

 

My NEW TIG Welder

Here's a picture of my new , Miller , Syncrowave 250 DX TIG Welder

I just brought it home today and Un crated it... I have a friend at work who has already set up some of these same machines where we work,
He's gonna gimme a hand....

First step towards my Tailwind W-10....

(Well, I already bought the plans)

Gotta Fly...
Mike in MN

 

Shiny!

 

All the "Bells & Whistles"

I just added All the Options on my new TIG machine ( $650 bucks )

the boards and dials on the right side of the panel....

Really cool features , This machine is better than most companys own.

Gotta Fly...
Mike & "Jaz" in MN

PS Now it's really shiny:ban:

 

Coool!!

Sheesh, you're as bad as me. Set yourself a budget, then see how badly you can blow it
I spent 2 grand on a TIG six moths ago - still haven't used it!!! but it sure is pretty.

 

Overtime Money

I didn't really go out on a limb to buy this machine...

and the money wasn't part of my buget ( what buget , I pay extra on bills , they all owe "ME" money...)

Anyway , I've had to work alot of overtime for the past 3 months

10 hour days & 5 on Sat....

Usually, when I get extra money like that , I throw it on the "principle" of my mortgage...

But this time I bought a TIG machine....Although , I'll be building my WOOD WINGS first.... I probly won't need the TIG for 6 months or more

But man are those "options" ( pulser & Sequencer ) Coool...

I've still gotta spend a couple hundred to get 100A wiring to the garage,

it only has 30A right now....

Gotta Fly...
Mike in MN

 

I have to agree with Wally. I just did my research for my first welding unit and decided on the oxy-acetylene set-up.

Got a good price on a Smith Airline torch model from Wag-Aero. I'll be burning holes in 4130 by the weekend. I'm looking forward to the learning.

 

I bought Kent White's Meco Midget kit. It is a wonderful little torch, only 6 oz. Attached are a some practice bits after about 4 sessions of messing around. I'm also going to master aluminum with it. According to Kent White, gas welds give superior results to alum compared to TIG for things like gas tanks.

Generally, lumpy welds are from having to stop and make corrections as you go. The smooth beads result when everything comes together and you just move the torch along and keep the puddle full.