Framebuilders - tig welding - really this "easy" ?

http://www.youtube.com/watch?v=VEEpikDY058

little demonstration video showing basic tig welding technique...
obviously the weld being shown is quick/dirty but...
is it really this easy? practice makes perfect?

regarding tig equipment maintenance, is there a good source of info on that whole other topic?

doing it is easy, doing it well is hard. I had a fabrication course in college where we did a bunch of different welding... it is pretty easy, but easy to ***** up as well.

for comparison, here's a long but very informative video on MIG welding.
my impression? mig welding doesn't seem as straightforward as tig.

http://www.youtube.com/watch?v=kJrBxABswjs

there's the co2/argon gas to buy/maintain. the flux feeder. etc.
tig welder? plug it in, feed the rod/wire by hand. maybe more tedious but simpler.

also i'm seeing that a lot of arc welding units claim to also do tig welding...
do you just hook up a tig welding torch to an arc welding base unit?
if so that's pretty fricken sweet since the price point for arc/tig units is around $250-300
with tig torches costing around $100.

Those scrap pieces from that original video are THICK. Try doing that with the sub-millimeter thickness material (like bicycle tubing) with consistent penetration, low spatter and (for bike frames) good aesthetics, and it gets exponentially harder.

Far from easy would be my experience. I have been heavily into dozens of crafts over the last 35 years, many of which require high end hand skills. I did a Psych test for work once, which also had a dexterity section, I got the highest score the researcher had seen in her decades in the testing business. TIG has still given me fits.

- One data point is that everyone who works at Bike Friday has to complete their own bike. I take this as evidence that if you have people who are expert in the particular type of welding you will do who are there to help you. And if you have access to perfect gear that is configured for the exact style of welding you are doing, then you will find it relatively possible.

- My data point is that if you are self-taught using less than the best gear (under 2K); attempting one of the more difficult styles of welding (thin and tubes), and you are making all your own guesses about the myriad variable, burning up your own materials and consumables, then it is hard as hell.

- I was reading this one guy's blog and his welds looked nice and he was a beginning builder, and I was thinking he was pretty good to make such nice welds... Lower in the Blog he showed a sample 72 degree joint he had welded to learn how to weld. He had done 100 of them. So I guess practice does pay-off.

- If you look at blogs from guys who attended the various schools - therefore experienced mucho hand holding and superior gear, they still say that they wish they had had more time to work on their welding. These are often folks who have welding backgrounds. Meanwhile, the guys who do the lugs course had extra time left over after they finished their frame to make a fork.

For steel you can use a simple DC source like an arc welder, you then need to add a torch, gas supply, pedal, pulse box, etc... After you do all that you are still stuck with a crap system, many of the parts of which can not be passed on to your new box when you upgrade, so that's money blown down a rat hole.

You should just look into what it costs to properly sharpen a tungsten in a home shop. To figure out what shape and trode works best in your machine.

My interest is so far mostly personal. I just want to make bikes with superior design, materials and craftsmanship for myself. In the meantime I am willing to contend with welds than may look like they belong on a Surly. But if you want to become a pro, who sells his stuff and holds his head high among his peers, then you are in competition with really good welders with Dynasty level systems. Not easy, and very expensive.

My learning period is not over yet, but I think gas welding as they do on aircraft tubes is a lot easier than TIG, and infinetly cheaper. Arc and MIG also have their advantages and difficulties as far as welding techniques go. exactly which is hardest is hard to say. In our little world TIG is the most elite, because it is difficult enough; requires separate manipulation of 2 hands and a foot; Is quite difficult out of position; and the work undertaken is normally more demanding than other forms. It's the kind of thing used on airframes or dragsters, vs. making up some hand rails. But the wide world of welding is vast and all the different types have their own elite practitioners. Should the guy welding Nascar frames with MIG, or the guy doing pressure vessels outside with a stick bow his head as the bike welder goes by?

for comparison, here's a long but very informative video on MIG welding.
my impression? mig welding doesn't seem as straightforward as tig.

http://www.youtube.com/watch?v=kJrBxABswjs

there's the co2/argon gas to buy/maintain. the flux feeder. etc.
tig welder? plug it in, feed the rod/wire by hand. maybe more tedious but simpler.

For TIG you have to have an argon cylinder as well.

MIG is easier to learn for sure. And quicker. But not as versatile, and can't do material as thin as bicycle tubing.

My learning period is not over yet, but I think gas welding as they do on aircraft tubes is a lot easier than TIG, and infinetly cheaper. Arc and MIG also have their advantages and difficulties as far as welding techniques go. exactly which is hardest is hard to say. In our little world TIG is the most elite, because it is difficult enough; requires separate manipulation of 2 hands and a foot; Is quite difficult out of position; and the work undertaken is normally more demanding than other forms. It's the kind of thing used on airframes or dragsters, vs. making up some hand rails. But the wide world of welding is vast and all the different types have their own elite practitioners. Should the guy welding Nascar frames with MIG, or the guy doing pressure vessels outside with a stick bow his head as the bike welder goes by?

Echoing what you've said, I've been taking welding classes at the local arts center and after playing with stick, gas welding, brazing, MIG and TIG, TIG has by far the steepest learning curve. (stick and MIG aren't really applicable to bike tubing)

I only recently produced a practice TIG joint on bike tubing without burning a hole in either tube. But the good news is that compared to a similar joint I did with O/A gas welding, the tigged joint was WAY stronger -- my breaker bars tore the tubing apart leaving the welded section intact. (Gas was the tech at the time they came up with 4130 aircraft tubing but I don't think they actually use gas to build planes any more) The gas joints I did were also weaker than a fillet braze... tomorrow I'll compare the tig joint to a fillet braze.

They sure do still weld airframes with gas. No problems with strength. In some ways it is more ductile in the filler and less porous. But it all works fine when done properly.

Brazed joints will work OK also just need correct sizing and execution. Therefore heavier.

Bikes are MIGed.

Can't use the same rod with TIG and Gas

I don't know whether gas is acceptable for welding non-4130 type tubes. Stainless for instance would be a pain.

in terms of just-gas welding... what are some key terms to look up? i assume this involves a similar rod or spool of 'solder' and a high-temperature torch?

They sure do still weld airframes with gas. No problems with strength. In some ways it is more ductile in the filler and less porous. But it all works fine when done properly.

Brazed joints will work OK also just need correct sizing and execution. Therefore heavier.

Bikes are MIGed.

Can't use the same rod with TIG and Gas

I don't know whether gas is acceptable for welding non-4130 type tubes. Stainless for instance would be a pain.

You're on about light aircraft, microlights and such, right? Just checking. Are you suggesting *IG welds are porous per se, or just when badly done and more difficult to manufacture without that porosity? And by porous, do you mean intermittent, not full of gas bubbles?

I do not, under any circumstances, recommend welding stainless steels with anything other than TIG.

[/Metallurgist]

"You're on about light aircraft, microlights and such, right? Just checking."

Aircraft welding in general. Many large manufacturers still did it until relatively recently and discontinued over health issues relative to welding fluxes, not because results were inferior to TIG. As Joe Maj in the 4130 tape put, there are situations where you need distributed heat, like welding clusters where gas is an advantage, and there are situations where you need very focused heat, like heavy sections where TIG is great. Bikes are a little more like the clusters case, but mostly light tubing which is accessible to either technique.

There are still some large makers of stuff like radiators that use gas welding because there is less probability of leaks with gas welding. Restorers who fabricate panels for aircraft and cars do sometimes use gas because the welds are less brittle and therefore can be more successfully post weld formed with things like English wheels.

"Are you suggesting *IG welds are porous per se, or just when badly done and more difficult to manufacture without that porosity?"

Per se, is what I have heard. Not sure what the cause is, higher heat being the obvious one.

" And by porous, do you mean intermittent, not full of gas bubbles?"

What is meant it that the material will past liquids or pressurized gases in more cases if expertly tigged, than if expertly gas welded. A perfect looking piece, as far as expert visual inspection is concerned will not pass a pressure test. These days tanks are often sealed with some kind of resin, to deal with the issue. People seem to mean the weld deposit is literally porous. A lot of very highly inspected welding is done on large pipes with TIG, and seems to turn out wonderfully. This problem seems most acute when dealing with thin metals that are used in light structures like thin wall tanks, or radiators. This is what those who continue to gas weld report, of course there may be others who disagree. It's good enough for me that someone is getting good results, who wins the bun fight is a different mater.



"I do not, under any circumstances, recommend welding stainless steels with anything other than TIG."

Why not? The industry sells consumables for all comon welding processes. Or do you just mean on bikes? I probably will never see a stainless bike tube, but since my Maxstar handles stainless I would probably use TIG and backpurge it. Getting the fluxes and all that for gas just seems like a hassle. I don't think the original poster is planing on using 953 etc... But just to avoid confusion, I have no experience welding the higher end tubes with gas. There was some builder who gas welds bikes Nordstrom (or some similar spelling)?

"in terms of just-gas welding... what are some key terms to look up? i assume this involves a similar rod or spool of 'solder' and a high-temperature torch?"

It is basically the same kind of torch used for lugs or fillet brazing. Those torches are in many cases actually designed for aircraft welding/similar stuff. Those little gas tips like. 035" are for welding. When used for other stuff like lugs, one has to be careful not to direct the flame right at the work for fear of overheating it. All you need in addition to the torch is a TIG like filler wire. RG 45 or RG 60 are some of the options

http://www.aircraftspruce.com/menus/to/welding_torches.html

These smaller torches are called "aircraft" torches, because they were designed for welding lightweight 4130 tubing in awkward positions, as back when the US was producing 100 000s of military aircraft a year. Not just ultralights etc...

I use the TinmanTech torch because it is a nice one and about half the price of other, particularly the tips, and they have specific parts for propane welding.

Here is a guy welding withe Henrob on some stainless.

http://www.youtube.com/watch?v=VsjCguncd6o&feature=related


And 4130

http://www.youtube.com/watch?v=aXxxe-goSuY&feature=related

Don't like the idea of welding galvanized!

I know some folks love the Henrob, but it was more than I wanted to pay.

I find TIG welding incredibly easy and fun.
But I've been doing it for almost 20 years.
Practice, practice, practice. Nothing better than a
boring-ass production job (1000's of the same stupid
little weldment) to refine your coordination and technique.

Here is a cool set-up, might be hard to adapt to a whole bike. :)

http://www.youtube.com/watch?v=u74wpNUlhQA

It isn't hard to weld say 3/16 plate. As you say, practice.

Start with 3/16, practice til it's easy.
Get some 1/8th, do the same. Make sure you do some tube joints.
Work your way down to .040".
Start building a frame!

Using a gas lens helps too.

My views on comparing methods of joining:
I`ve had a tiny bit of formal training at stick welding, informal help and learning by semisupervised practice for MIG and TIG by people who aren`t dedicated welders. While most people seem to find MIG easier, I find TIG much easier for anything but big stock (angle iron, plates, etc). After the first few hours of practice, I had my TIG technique figured out to the point where I really haven`t progressed much over the seven years or so since. Since the begining, I`ve had no problem TIG welding mild steel down to about 1/16 (still much thicker than any bike tubes). My MIG welds are notoriously ugly, especially if I don`t luck out by finding the machine already set up for what I need to do. For some reason, I just don`t "get" MIG. For reference, I work in the maintenance department of a big printing plant- none of us are actually welders per se, we just do whatever welding and fab work that needs to be done throughout the plant.

Fillet brazing seems to be the ticket, at least in my opinion. I had zero training in brazing and nobody in our shop had any but the most Flintsone brazing skills, so I bought the needed suplies and went to it, following advice I got from the internet. I`ve been dinking with it occasionally for about a year, maybe two, but with very few hours actually devoted to it in that time, and my brazing skill is definitely better than my welding of any kind.

I leave for two minutes hehe....

I'll do them one at a time...



Aircraft welding in general. Many large manufacturers still did it until relatively recently and discontinued over...etc.

Not that I'm trying to get into an argument, here, man, but I'm still not following... Civil aircraft don't have any welded structures in steel, nor do any military airframes that would be gas welded. It's either TIG or EB for fusion jointing. US Mil won't accept anything else, and the European manufacturers wouldn't either. I'll go with the light aircraft, yes, and microlights, as I mentioned because the manufacture of those is not as... I hesitate to use the word 'stringent', perhaps potentially litigious is a better expression.




There are still some large makers of stuff like radiators that use gas welding because there is less probability of leaks with gas welding. Restorers who fabricate panels for aircraft and cars do sometimes use gas because the welds are less brittle...etc

They do use gas, yes, but in most restoration shops over here, that's because they don't have TIG proficiency and the cars were spot welded or seam welded in the first place and the repair jointing method doesn't matter a jot.

If we're talking large radiators, then, bunkum. If we're talking fine radiators, a la cars engines, the double bunkum. A gas torch, even very finely controlled is essentially a redox reaction with potentially a big ole pile of carbon floating about. You're essentially turning a piece of steel sheet into Bessemer iron or rimming steel in the weld pool, both of which had pockmarked surfaces when they froze. Either you oxidise the steel with a lean flame and the carbon contained turns to CO2, or you carburise the steel and flame oxygen intermittently does the same.

The suggestion that *IG welds are more brittle is contentious at best. I'm not jumping on your experience here, but the risk of pick-up of contamination is far higher in a fuel-oxidiser flame, carbon and oxygen both bad for almost all welds as I said. Which brings me onto...




Per se, is what I have heard. Not sure what the cause is, higher heat being the obvious one.

While higher heat affects solubility of gas in a liquid metal pool, conversely higher heat and a bigger heat affected zone leaves it liquid for longer, allowing more time for gas to be ejected at the solidification front as the pool freezes. It's a little of swings and roundabouts. This is beginning to sound like all the defects you've witnessed in the poor *IG welds you've seen are down to poor prep, which will
equally kill any otherwise good welding setup and is doubly shameful in TIG because a welder should understand that.




What is meant it that the material will past liquids or pressurized gases in more cases if expertly tigged, than if expertly gas welded...etc

Have you come across this yourself? Because this is the very first I've ever heard of it. As far as pressure vessels are concerned, neither method in this thread is acceptable. They should be multi-pass SMA welds with interpass anneals/normalises. To support gasses under pressure, the kind of section thicknesses are usually beyond the scope of TIG. Any 'porosity' encountered is more voids than gas dispersion, caused simply by not having enough penetration depth, limited by the process. I wouldn't expect a welder who specialises in one method to the detriment of another to report anything outside of his field of experience.

Second, no resin on earth will hold gas pressure if the metal won't. Falanx first rule of polymers:

#1.) there is no such thing as a gas-tight polymer.




Why not? The industry sells consumables for all common welding processes. Or do you just mean on bikes? I probably will never see a stainless bike tube, but since my Maxstar handles stainless I would

Because stainless steels are predicated on being very very low in the kind of impurities that gas welding is wont to introduce. Those impurities - carbon especially - will sensitise a welded structure thus removing the stainless steel's raison d'etre - it's corrosion resistance, as well as removing toughness.

Just because a company decides there's a market gap for a product doesn't mean that product is a good idea. See: GM's Vauxhall Astra MK3 rear offside interior wing.

"Not that I'm trying to get into an argument, here, man, but I'm still not following... Civil aircraft don't have any welded structures in steel, nor do any military airframes that would be gas welded. It's either TIG or EB for fusion jointing. US Mil won't accept anything else, and the European manufacturers wouldn't either. I'll go with the light aircraft, yes, and microlights, as I mentioned because the manufacture of those is not as... I hesitate to use the word 'stringent', perhaps potentially litigious is a better expression."

I'm not saying the latest stealth bomber is being gas welded. I don't have the online time any more to research this stuff, unless it is on some of my DVDs, but I think Ken White said soemthing about Boing as having done it in the 80s. As mentioned there remain some large manufacturers of other stuff like truck parts and screen doors that still gas weld. Or where when the Tapes I have were being put together. There probably aren't any commercial ultralite, etc... people doing it with gas either. There is commercial restoration work on a much larger airframes than ultralites still being done. The torches and consumables are very easily available, say 10-20 locations within 20 miles of where I live.

There are several related questions that tend to trip over each other in this thread. Can tubes be gas welded, yes aircraft including some large aircraft of the past. Does anyone still do it. Yes individuals, restorers, and certain manufacturers still gas weld light structures. What can the home guy sensibly do for a low buck: Gas welding seems a better option than low end TIG, and about 5% the cost of good TIG.


"They do use gas, yes, but in most restoration shops over here, that's because they don't have TIG proficiency and the cars were spot welded or seam welded in the first place and the repair jointing method doesn't matter a jot."

This is beyond that. Talking about whole sheet metal panels etc... Talking about tanks and radiators, talking about people with both Miller TIG and gas in the same shop. Talking about people who teach welding for a living.

At the margin it is irrelevant to me whether one method is metallurgically better than the other where 4130 tubes are concerned (not to the say the discussion isn't useful). As long as results are stronger than strong enough. In fact what maters about welding bikes is mostly all the subjective stuff from the look of welds to how the rig fits into the middle of shop processes. The most important technical issue for me is actually distortion and how one controls metal movement and part alignment.

What maters in this thread is whether it makes more sense that jazzing up a stick welder. TIG is an electrode, hand held filler metal, and a blanket of gas. Some TIG sucks. Some machines are wonderful. Gas welding is absolutely better than some TIG machines, it is giving my maxstar a run for the money.

"If we're talking large radiators, then, bunkum. If we're talking fine radiators, a la cars engines, the double bunkum. A gas torch, even very finely controlled is essentially a redox reaction with potentially a big ole pile of carbon floating about. You're essentially turning a piece of steel sheet into Bessemer iron or rimming steel in the weld pool, both of which had pockmarked surfaces when they froze. Either you oxidise the steel with a lean flame and the carbon contained turns to CO2, or you carburise the steel and flame oxygen intermittently does the same."

I'm just giving you a reference, I think I can find the actual referenced company. I think it was Peterbuilt, would have to look it up again, and it may now be 10 years out of date. It would still be interesting that even ten years ago gas held it's own in an unsentimental manufacturing setting.

"The suggestion that *IG welds are more brittle is contentious at best. I'm not jumping on your experience here, but the risk of pick-up of contamination is far higher in a fuel-oxidiser flame, carbon and oxygen both bad for almost all welds as I said. Which brings me onto..."

Not my specific experience. I have experience with both welding types, but not with any testing done to them. My interest is just that there is a 100 year history of steel welding in lightweight tubular frames which is not what one would get from learning all one's welding from a bike chat setting. It remains the preferred welding type for some 4130 aero types, one pro bike builder, and some industries in certain setting.



"Have you come across this yourself? Because this is the very first I've ever heard of it."

I have no personal experience, I hope someone at the nearby nuke plant has all this worked out.


"Second, no resin on earth will hold gas pressure if the metal won't. Falanx first rule of polymers:

#1.) there is no such thing as a gas-tight polymer."

"Gas" as in "petrol". My various multihulls certainly show that epoxy passes vapour!




"Because stainless steels are predicated on being very very low in the kind of impurities that gas welding is wont to introduce. Those impurities - carbon especially - will sensitise a welded structure thus removing the stainless steel's raison d'etre - it's corrosion resistance, as well as removing toughness."

What about the use of flux? I don't think anyone expects the welded stainless to be as good as the un-welded stainless. TIG doesn't protect the back of the tube backpurging does, which is an option with gas welding also. Easier for me even since I won't be using that argon for the welding :). I'm not sure why backpurge with flux under the flame wouldn't work. Also not sure why mig wouldn't work. Or MIG in an inert gas chamber. Also, even in bikes, some stainless welding involves attaching stainless to carbon steel, so the issue of corrosion may not be a large issue. In certain cases the parts may be beefy, stainless drops to chainstays come to mind, and weld strength may not be as critical as it might in a part carrying the big loads.

I have little idea what is up with the welds. It does occur to me that some of todays fancier welders have all kinds of adjustments on them so one can massage the weld pool with great finess, so there can be a lot going on in there. Though I think the issue is with simpler machines originally.

"Just because a company decides there's a market gap for a product doesn't mean that product is a good idea. See: GM's Vauxhall Astra MK3 rear offside interior wing.[/QUOTE]"

Has the Vauxhall been available in every part of the industrial world, distributed at retail locations every 10 miles or so for 50-100 years?

theoretically speaking, then... it would be possible to weld a bike frame incorporating lugs using just a gas torch and filler wire?

You can do a whole bike with lugs, using a torch to braze it together. That is how it is done. This is not welding, but brazing. You can braze the tubes together without lugs also. The three basic methods are welding, fillet brazing, and lugged which is brazed together a bit like a copper plumbing pipe, except the filler is either "silver" or bronze and uses the high heat of the OA torch.

Here is a frame being brazed together:

YouTube- Taylor Brothers from 'The Green Machine' documentary.

Great video, PP! The different ways that three mfgs go at it was insightful and I really loved watching the Taylor clan`s decidedly old tech methods. Thanks for posting it.

I think someone is mistaken here... "Gas Welding" is "TIG" TIG = Tungsten Inert Gas. While TIGing you always need a constant flow of an inert gas such as Argon so that the welds will not get contaminated. Its also a little more tricky b/c while doing this you HAVE to keep the filler rod inside the gas flow while moving the torch, dipping the rod and moving the foot pedal up and down multiple times to keep the heat right. If you just floored the pedal the whole time you are very likely to blow a hole right through your frame...

TIG is the most difficult to learn at first but once you get it then its great. Welding 3/8" plate is a LOT different from welding .038" TUBE in several positions.

Gas welding generally refers to Oxy/Acetylene welding with a flame and filler. I suppose nowadays you have to clarify.

as for welding rounded surfaces, i imagine it would be easier to work with square tubing (with the exception of headstock leading up to handlebar since that needs inherently to Be round) ? maybe not as aerodynamic but i actually would adore the look of it and dream someday of building a bike like that... where i'd find square lugs, who the hell knows! :)