fifidibosco
Well-Known Member
Hi all,
what type of welding you used for the fuselage ? oxyacetylene ? TIG ? other ?
Phill
what type of welding you used for the fuselage ? oxyacetylene ? TIG ? other ?
Phill
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fuselage welding
- Thread starter fifidibosco
- Start date
TFF
Well-Known Member
I have used both OA and TIG. I consider them interchangeable on 4130 fuselages. TIG has the advantage of tighter control and not having a flame.
My opinion is if one wants to MIG, they better be the best and understand the pitfalls of each joint to be welded. I know of two aircraft that had landing gear repairs with MIG and the gears collapsed. They never got the penetration, but it looked good. MIG can look good and not be so. TIG and OA can look horrible and be good. MIG has been done with success, but it took extra care that most MIG welders are flippant towards.
My opinion is if one wants to MIG, they better be the best and understand the pitfalls of each joint to be welded. I know of two aircraft that had landing gear repairs with MIG and the gears collapsed. They never got the penetration, but it looked good. MIG can look good and not be so. TIG and OA can look horrible and be good. MIG has been done with success, but it took extra care that most MIG welders are flippant towards.
10kDA
Active Member
Oxyacetylene, because that's what I learned, that's the gear I have, and the results are as good as any other method. According to many old-time sources 4130 was formulated to obtain favorable results with oxyfuel welding methods. That was before TIG/"heliarc" was around, but it works just as well with those processes. As TFF states, MIG welds can by deceptive and you may find out the hard way they were not adequate. Best to not waste time with it IMHO.
CdnMedic
Well-Known Member
Currently I'm using TIG for my Sonerai fuselage. I have a "cheap" primeweld 225 machine. It works just as good as the 3x the price miller at work.
A decent OA set up with 2 bottles, the hose, regulators, torch etc isn't much cheaper than a machine like that. I use use a torch with MAPP gas when I need to heat up longerons for bending.
I have a MIG machine as well... I'm good with it, but it's used for making trailers, general home repairs, body work etc.
A decent OA set up with 2 bottles, the hose, regulators, torch etc isn't much cheaper than a machine like that. I use use a torch with MAPP gas when I need to heat up longerons for bending.
I have a MIG machine as well... I'm good with it, but it's used for making trailers, general home repairs, body work etc.
A good used gas setup can be had cheap on Craig's List. I don't think I would trust any TIG bought for the same price.
Gas takes up less space in the shop, costs less to run while you are learning to weld, and can weld stainless, braze, silver solder, cut, preheat parts for big welds, straighten overbent tubes, stress relieve clusters. List goes on... Oh, and most of us gas weld bare handed - no helmet, leather gloves, pants, and jacket to prevent arc light burns. Just dark enough lenses to see what we are doing.
Buy and build in OA, be happy.
Billski
Gas takes up less space in the shop, costs less to run while you are learning to weld, and can weld stainless, braze, silver solder, cut, preheat parts for big welds, straighten overbent tubes, stress relieve clusters. List goes on... Oh, and most of us gas weld bare handed - no helmet, leather gloves, pants, and jacket to prevent arc light burns. Just dark enough lenses to see what we are doing.
Buy and build in OA, be happy.
Billski
weld puddle control is the skill needed and the ONLY way to have that is by never looking away from the puddle while welding. ALL of the info about the quality of any weld is visible in the puddle.
tig, mig, gas, even stick have and could be used. so the question of which gear is less about quality and more about other considerations.
gas is great, needs no power and can be used for a general high heat source for countless other metal working, forming and joining tasks
tig is great, good machine needs 220v, and argon is expensive and other metals need other gases
mig will be expensive to set up right for thin wall tube and offer no advantage, unless that is what the welder is already ultra proficient at already and or just bloody determined.
stick would be just mad skills showing off and driving
people nuts some of my friends are truely top shelf welders and can do stuff with an ac buzz box that should be impossible, and yet looks (and IS) perfect
skills acquired doing countless miles of critical and high pressure welds that are then xrayed, and never have any rejects, because they watch the puddle, and when a bit of dirt or slag, drops, they see it, stop, grind it out, clean everything up, and start welding again
simple eh!
tig, mig, gas, even stick have and could be used. so the question of which gear is less about quality and more about other considerations.
gas is great, needs no power and can be used for a general high heat source for countless other metal working, forming and joining tasks
tig is great, good machine needs 220v, and argon is expensive and other metals need other gases
mig will be expensive to set up right for thin wall tube and offer no advantage, unless that is what the welder is already ultra proficient at already and or just bloody determined.
stick would be just mad skills showing off and driving
people nuts some of my friends are truely top shelf welders and can do stuff with an ac buzz box that should be impossible, and yet looks (and IS) perfect
skills acquired doing countless miles of critical and high pressure welds that are then xrayed, and never have any rejects, because they watch the puddle, and when a bit of dirt or slag, drops, they see it, stop, grind it out, clean everything up, and start welding again
simple eh!
I've been reading "Construction of Tubular Steel Fuselages" by Vex Aviation and it says to use Oxy/Acetylene or TIG, with TIG being the favored method. The author states that 4130 will harden as it is heated, losing malleability and making it more susceptible to cracks and that TIG is much less likely to heat saturate the part as can happen with gas. I know arguments have been made for heat treating welded frame clusters with an oxy torch and the book addresses that as well, saying that test welds have been done, cut, and studied and no real advantage has been detected. I'm still on the fence but leaning towards TIG.
A quick search shows that there are only about 200 threads on the subject of which welding method(s) are best. Some also include discussions about brazing. I’ve run out of new comments on the subject.
BJC
TFF
Well-Known Member
It’s easier to start with OA. It’s just a two hand operation. TIG is usually a three limb exercise two hands and a foot unless one has the finger adjustment. I have an old Miller that needs a foot control. It is a pain without, as I have to stop and adjust as you go through a cluster. It was inherited from a friend. I usually just go borrow another friends Lincoln with all the bells and whistles now. The OA will make you learn how to make and hold the puddle. Adapting to TIG is easy from OA. The thing about OA is things like forming finger patches or other heating is useful. OA is multiple tools in one. TIG does one thing well. I like having both together.
I've used both, as I learned to use the OA process back in A&P school, back in the 1980s. Now I am favoring TIG, but it definitely takes practice to teach an old dog new tricks. That said, either works fine.
As I understand the metallurgy of 4130, it's all about the cooling rate. Cool slowly in still air and the crystalline structure of the metal will remain favorable. However cool too quickly and you'll get untempered martensite which, although much "stronger" than tempered martensite or austenite, it's also significantly more brittle as well.
There's a great book by Gerald Utracchi called Advanced Automotive Welding, where he goes through all of the theory I just glazed over. Suffice it to say that it's significant. That said though, most people I've spoken to on the matter in the past several years now seem to favor the GTAW (TIG) process over the OAW process, for the reasons already mentioned in this thread. So this old dog is trying to learn new tricks, and I plan to employ TIG to weld my next project...starting later this year. The good news though, is that if you learn OAW first, then you'll be that much further ahead if/when you do decide to move to TIG. The technique is quite similar--although this old dog is finding that TIG welding requires MUCH more precision than OAW does. The pile of metal over in my scrap bin will tell you that...
As I understand the metallurgy of 4130, it's all about the cooling rate. Cool slowly in still air and the crystalline structure of the metal will remain favorable. However cool too quickly and you'll get untempered martensite which, although much "stronger" than tempered martensite or austenite, it's also significantly more brittle as well.
There's a great book by Gerald Utracchi called Advanced Automotive Welding, where he goes through all of the theory I just glazed over. Suffice it to say that it's significant. That said though, most people I've spoken to on the matter in the past several years now seem to favor the GTAW (TIG) process over the OAW process, for the reasons already mentioned in this thread. So this old dog is trying to learn new tricks, and I plan to employ TIG to weld my next project...starting later this year. The good news though, is that if you learn OAW first, then you'll be that much further ahead if/when you do decide to move to TIG. The technique is quite similar--although this old dog is finding that TIG welding requires MUCH more precision than OAW does. The pile of metal over in my scrap bin will tell you that...
4130 is fool proof,not damnfool proof,but it is tough and forgiving ,does not "air temper" and get glass hard
and as pointed out countless miles and miles of it were welded by farm boys,competent but disinterested
in anything much to do with welding
and as pointed out countless miles and miles of it were welded by farm boys,competent but disinterested
in anything much to do with welding
"Miles and miles" of 4130 have been welded by "farm boys"? Interesting. It may be forgiving, but nonetheless it still does have a higher carbon content than something like carbon or "mild" steel, so it does need to be respected a bit...especially where life and safety is involved. And the real problem is that different "authorities" tend to have different recommendations on how to best weld the stuff. For instance, Lincoln states that no pre-heat or post-weld treatment(s) is required for wall thicknesses under 0.120", while the FAA still seems to recommend post-weld stress relief in those tubing wall thicknesses.
So yes, I agree that it IS relatively forgiving. However it's pretty evident that there isn't universal agreement on how best to weld it--and it's best to keep that in mind when reading online forums such as this.
So yes, I agree that it IS relatively forgiving. However it's pretty evident that there isn't universal agreement on how best to weld it--and it's best to keep that in mind when reading online forums such as this.
I hate seeing misinterpretations like this. Let’s clear some stuff up.
First let’s talk about steel. Every steel alloy I know about becomes less strong as temps go up. After cooling, what strength and ductility you get is a function of how hot it got, low long it stayed hot, and how fast you cooled it.
If you get it above critical temperature and cool it back down slowly, it can end up lower strength and higher ductility after cooling than it started -this is annealing.
Take it above critical temp and air cool it, and that is called normalizing. In 4130 normalizing and annealing produce close to the same results.
Cool steels from above critical temperature fast and you raise strength and can make it brittle. This is quench hardening. Some steels can be brittle as glass this way. Parts in this state usually need tempering too. We deliberately avoid this in 4130 weldments by welding and cooling parts only in still air.
Take a quench hardened steel back up to intermediate temperatures, and you draw some of the hardness off and make it much tougher and more ductile. The hotter, the more reduction in strength and the more increase in ductility. This is tempered steel. Some 4130 parts are quenched and tempered, but most 4130 parts in homebuilts are just air cooled.
Each steel alloy has its own set of temps, times, cooling rates, etc, to achieve annealling, normalizing, quench hardening, tempering, etc, but they ALL have these sorts of behaviors.
As to gas heat saturating 4130, I do not even know what that means. Can you weld with less heat in the parts with TIG? Yeah, and you can make either one worse with bad technique. Does gas make 4130 crack and TIG not? Some folks can wreck an anvil… Learn what you are doing with either one. Sportair workshops are a good investment. Both make fabulous assemblies.
The arguments are rampant for and against stress relieving welded clusters. I do it anyway. It can not hurt things. Just pull the torch away slowly from the last weld on a finished cluster, and it is done.
TIG is fine if you get trained and have plenty of money and space. Gas is equally fine if you get trained. I am tight on space and do not spend money I do not need to, so gas is how I weld. See my build log to see my rudder pedals, sticks, and other assemblies.
Billski
fifidibosco
Well-Known Member
Maybe a link..... thank you
Pilot-34
Well-Known Member
This might be me. After miles of rod I’m pretty comfortable with stick. Not sure if I’m good with it but I’m sure comfortable with it.
A few years ago I welded up a project involving about a ton of steel the smallest section of is 1 1/4 inches thick. Being in a friends shop in the center of town it was fun to see how many people would come by the shop and decide I didn’t have a clue what I was doing and want to show me how to do it right .
Judging from what I saw them do I hope welding 1/8 or even 1/4 inch stuff is far far different than inch and a half . And all of these yahoos, were either production welders or locals, with really good welding skill reputations..
Luckily, I could usually knock the Welds back off with a hammer only a very few required much use of the grinder.
Not one , not a single one of these supposed Mavins of the molten metal did any prep work.
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Bill, I second that build log request.
It is in the Build Log section on this forum…
https://www.homebuiltairplanes.com/forums/threads/billskis-fiberglass-bird.8344/
Posts 12, 16, 20, 34, 36, 38, 48 show you weldments and brazed assemblies made by yours truly.
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