bike frame welding

September 16, 2011 12:09 PM

How long would it take me to learn to weld steel and aluminum bicycle frames?

I'm looking to take welding classes through a community college. Without any prior experience, how much in classwork (roughly speaking) might it take me to become competent at welding bicycle frames? Months, less than two years? Or more?

posted by mnemonic to sports, hobbies, & recreation (11 answers total)

Got to have the right welder for each metal. Most welding classes around here(TX) can be six weeks to a year depending on if you can get in one short coures offered by local certfied welders. Welders are in short supply here so all the local are taking on students.
posted by bjgeiger at 12:14 PM on September 16, 2011

Welders are in short supply here in Colorado too, so we do lots of in-house training. We do mostly TIG welding and I think the basic certification process takes about 6mos but we have extremely high standards.

I manages to stick two pieces of metal together the very first time I tried it but i sure wouldn't have trusted that weld with anything resembling stress.
posted by Confess, Fletch at 12:18 PM on September 16, 2011 [1 favorite]

the United bicycle Institute teaches a framebuilding class that lasts about two weeks, I think.

In it, you build a frame.

But I think that the time involved in learning framebuilding isn't just the welding. It's the measuring, the cutting and mitering and filing and the prep work.

I'd hazard that there are people doing it for decades who are still learning and perfecting their work.

But, if you want to build a frame and have some ideas on what to do for the second one you build, then, two weeks. Whether or not you'll have the resources to build the second one is a different question.
posted by entropone at 12:37 PM on September 16, 2011

I can't speak from experience welding bike frames but several things are important. As bjgeiger said, you need a different kind of welder for each metal. The metals will weld differently, with different preferable angles, weld speeds and feed speeds. Aluminum is supposedly very temperamental to weld. I've only done steel myself.

The other tricky thing with bike frames is learning to cut and space your metal well, in addition to the difficulty in clamping the tubes down so that your shape is correct. The fishmouthing of the tubing can be tricky, especially without the right tools. Here at my job we use a holecutter in a mill, but it's less than ideal.

I would say 6 months to making a usable frame, if you focused on steel first and were in the class at least once a week. The key things to learn are a steady hand/pace, to watch your weld pool, to learn how to change the settings on the welder for the thickness of the metals, and how to size the metal appropriately in your pre-welding prep.
posted by JauntyFedora at 12:40 PM on September 16, 2011

Months, not years, to get the basics of steel welding. I'm no expert, but I taught myself how to make simple rebar structures for the back yard by buying a $100 welder at Walmart and just experimenting. I do recommend taking a class or two, but that's all you'll need to figure out if you have the skill and determination to do more. You should be able to produce something satisfying pretty quickly.

Learning to weld is dead easy. Learning to weld well is another story.
posted by MrMoonPie at 12:50 PM on September 16, 2011

I'm gonna throw a wrench in here: If you're building steel frames, braze, don't weld. This has two advantages: If you can solder, you can braze, and it's easier to control the tempering on the existing steel with brazing.

It's going to take a little while to get good at it, but with an oxy-mapp torch you can be carving existing bikes into Burning Man capable vehicles in an afternoon (that's as far as I've gotten). And then, as others have said, it's a matter of how good at learning you are and how much you practice.
posted by straw at 1:20 PM on September 16, 2011

Having been a welder long time ago, I can tell you that you can literally teach anybody to weld. The bigger picture here is design and fit.

I agree with straw that you should start out brazing frames. There are YouTube videos that teach you how to braze lugged frames at home in your garage or back yard using readily available frame components and tools. This method constrains your design to the frame geometry in your chosen lugset, so you can concentrate on the fabrication techniques before you get boggled by the limitless universe of custom framebuilding.

Dive right in and make your first frame this way. Take the welding class and then try to mimic what you did brazing with your TIG welding.

Learn how to use BikeCad Online.

As for how long does it take? Ask any framebuilder about the best bike they've ever made and the best ones will tell you "It's the one I'm working on now." It's not ego, but it's their pride at implementing their constantly growing knowledge and skill.
posted by No Shmoobles at 2:30 PM on September 16, 2011

As a reference as to what's involved, here is a gorgeous video of a talented guy fabbing up a bike frame.
posted by davey_darling at 3:14 PM on September 16, 2011 [1 favorite]

Hi there! Amateur steel framebuilder here.

It's not clear from your question if you are actually referring to to welding, or simply using it as a euphemism for sticking metal together with heat. Let's assume the former, then answer the latter.

Anyone can learn to weld. Not everyone can learn to weld well. If you want to weld steel and aluminum bike frames, then the only real choice is TIG welding. TIG welding is not easy, and will require you to be able to do at least two operations independently and simultaneously - manipulating the torch with one hand and the filler rod with the other. Add to that, adjusting a amperage control with your finger or your foot and things are getting pretty busy.

A few people upthread have said that you need different machines for steel and aluminium. That's not strictly true: steel and titanium require DC TIG, and aluminium requires AC TIG, but most of the machines that are used for frame fab are combination AC/DC machines, as they tend to be the ones with the features that you want to be using eg upslope, post gas, crater fill, adjustable pulsing etc.

TIG is demonstrably more difficult than other forms of welding like MIG and stick. I've been stick welding and oxy/acetylene welding and brazing for 15+ years, and MIG welding for over 12, but I still feel like a novice a year into learning to TIG. I've built over a dozen steel frames and forks, but I would not feel comfortable TIG welding them yet. There is a huge difference between laying down TIG welds on 2mm thick mild steel pipe and doing the same on bike tubes. To put it in perspective, steel tubes with .7mm walls are far from uncommon. The difference between 'not enough penetration' and 'oops, I've blown a hole in the tube' is pretty damn fine.

In short, I wouldn't recommend starting to learn framebuilding with TIG welding. The other aspects of the craft - frame design, metal prep, alignment, fixturing etc are all to complicated without adding a further process to master. Oxy acetylene or oxy propane brazing are a little more forgiving, particularly when done with lugged construction. I don't know *any* builders who have started directly with welded construction save for one or two who were already absolutely gun TIG fabricators for aerospace or motorsport already.

I don't know if it's the answer you're after, but community college welding classes are not going to teach you to weld bike frames. At best, it's going to give you a sufficient grounding for you to go away and practice a whole lot while you teach *yourself* to make bike frames. And to do it well is going to require a massive commitment in both time and tooling. Not to discourage you - I learned to weld in a 10 week community college course, but that was just the start of the journey, not the end of it.
posted by tim_in_oz at 4:32 PM on September 16, 2011 [1 favorite]

I've built over a dozen steel frames and forks, but I would not feel comfortable TIG welding them yet.

What I shoulda typed was 'I've brazed over a dozen frames and forks'.
posted by tim_in_oz at 6:41 PM on September 16, 2011 [1 favorite]

1. You have to do "out of position" welding on bikes. When I took a "Safety and Basic Use" class at TechShop, we did some TIG of two steel plates flat on a table and I was just a smidge above terrible. We were advised to come in and practice just that a LOT and only then sign up for TIG 1, which was still "in position" and TIG 2 which includes out of position (vertical welds) and welding curved surfaces.

2. Metal moves when you heat it. The jigs for holding tubes in place are expensive, though I've seen some impressive DIY jigs. Brazed (or even MIG wire-fed) punk & junk bikes are made without jigs, but you don't need a derailleur (precise alignment) on a mesa but even a junk bike will be no fun if the chain falls off every 20 feet.

3. Welding causes alloying metals (stuff other than iron or aluminum) to come out of solution and change the structure & therefore strength. For steel, you can get "air-hardening" alloys that actually get stronger, but regular 4130 Chrome-Molybdenum and 525 will become brittle around the weld (the heat affected zone). Aluminum has this problem even more. Mike Ahrens uses 7005 because it only has to be "artificially aged" (alloying materials precipitate out of solution on their own over time, this speeds up the process a bit), but 6061 requires[PDF] a much hotter "solution heat treatment" first that requires either heating in a jig or re-bending after treatment (or both). You can't (well, shouldn't) powder-coat aluminum because the curing oven heat is enough to cause aging (you want some for stiffness, but not too much to the point of brittleness).
posted by morganw at 2:22 PM on September 17, 2011