DIY AC TIG Welder using an e-bike controller?

[Indubitably]

Yeah, money is something of an issue, but then money is always going to be an issue, and I was figuring on consumables cutting into my budget either way. AC tig is where I would prefer to invest my practice time, because aluminum is the material I really want to work with, but perhaps a used oxy acetylene setup and brass brazed 4130 chromoly would be a better place to wet my feet. You just don't see used AC tig machines around here for less than $1000, (which is pretty tough to justify when I could get a brand new Chinese machine with a built in plasma cutter for the same price), but every now and again you do see an oxy torch and a couple of bottles with new regulators hit Craigslist for something like $300. I suppose that would be sort of like learning to play the piano when what you really want to so is play the electric guitar, but once I get good enough with the oxy that its making me more money than its costing, I can justify dropping the cash on a tig machine without worrying that it will wind up sitting on a shelf because I can't afford the argon.

[iamsofunny]

Look up tinmantech videos on Youtube and his oxy acetylene welding video
He uses flux on a 5356 rod to "weld" (more like braze) the 5000 series aluminum. and I''m sure the 5356 rod works on 6061 too.
It's slow but effective.
The 4043 rod doesn't oxidize as easily, melts at lower temp, flows better and doesn't crack as easily when cooling though. The 5356 is stronger, slightly..
Don't buy a tig, it's too expensive.
Don't use alumiweld or any other zinc based solder.

Also for battery cases you can use 1/8 ply and 2 layers of thin fiberglass cloth
And you can weld steel pretty easily with a stick electrode at a lot of angle for cheap but obviously heavy material. Strong though.

I built fishing boats in the Caribbean for 3 years. We used 1/8" thick of fiberglass. I suspect you could build a frame out of 1/4" thick layers around wood and it would be strong. Not the best idea but fiberglass has its place for certain applications such as side panels, battery mounting and fastening torque arms permanenlty

[Indubitably]

Well, its not so much about building battery cases as wanting to learn how to do tig on aluminum. Granted, it would definitely prove usefull on my bike projects, and that is one of my major motivators for choosing aluminum tig in particular, but welding is a valuable skill in its own right. At first, it will just be a hobby, and like any hobby I am expecting it to eat into my bottom line, but if I'm smart about it, and practice every day, I figure I should eventually get to where my "hobby" makes me more money than it costs. If the practice was a chore, I probably wouldn't bother, but I dig working on this kind of stuff. After a day of cramming theory into your head for 8 hours straight sometimes you just want to grab a dremmel or something and start monotonously grinding out widgets untill you hit just the right shape. I'm not looking to create a masterpiece, or make a fortune, I'm just looking to make widget #47 a little bit prettier than widget #46.

PS:

Fibreglass is some pretty groovy stuff, and I've been toying with the idea of layering it with aluminum flashing to produce a very light yet sturdy fairing, in much the same way that they do with an airplane fusilage, but to design and build a decent carbon fibre frame is a lot more challenging than it is with aluminum. Aluminum might be a difficult and expensive material to master, but from a design standpoint it is actually fairly forgiving. Its light enough that when you inevitably screw up your design, you can pretty much just keep adding volume and or increasing diameter untill its strong enough to hold, and its rigid enough that it will probably more or less move how you expect it to move. Hell, at this point, I'd probably preffer to focus on frame construction even if I was just working with mild steel. I'll worry about building a cart with fancy materials and groovy excessories once I've actually got myself a good horse or two to put in front of it.

[iamsofunny]

I have been building aluminum frames for about 4 months now. I don't really recommend trying unless you have lathe or small cnc or at least a drill press. But to make the head tube you'd need to either lathe it or drill it. The bottom bracket needs to be milled after welding because it goes oval so you can't buy a premade bb shell for that purpose. After welding it needs to be baked at 400F for 1 hour so the heat affected zone (HAZ) rehardens so you'd need a large enough oven. I didn't do this for my frame but I'm not selling them so it's not a problem.

I think you're in a similar position of when I was in college. I previously had done woodworking all day every day and then had to go sit in a classroom to be indoctrinated with radical leftist ideology (Business Administration program). I went home every weekend to work in my shop.

Maybe you need a part time job at a fabrication shop or something. A lot of students to unpaid internships doing administration work but I'm sure there are fab shops that would take on a low wage apprentice on the weekend

[Indubitably]

Well, I'm an idea man, always have been really, so theory is a good place for me to be, but sometimes when you've got a dozen different ideas all pulling you in different directions, there is a very real danger of either stalling out somewhere in the middle, or just plain biting off more than you can chew and subsequently choking on the whole lot of it. I actually went back to school after being self employed as a PC / home LAN tech for about 8 years, so it took me a while to figure out that sometimes a lack of structure and consistency can, in and of itself, create a pretty serious bottleneck, but it is finally starting to sink in. Never much cared to be tied down to any one way of doing things, but the more I work on improving those skills that demand a regular and consistent dedication to technique, the more I realize that its something that has been sorely lacking in my life. It probably wouldn't kill me to pick up some work in a shop to be honest, but this is really more a "Zen" sort of a thing for me, and I'd rather use it to destress in a solitary down-time environment at the moment.

All the same though, I'm starting to think you're right about getting into TIG right now. I picked up a thing or two from my brother about building kilns, so I could put an oven together that could hit 400 degrees if I needed to, but that means seriously getting into oven building, and heat treatment of aluminum, and TIG, in addition to what I'm already doing with electric conversions. With the skills I have right now, I probably will get a much stronger joint out of a can of hysol 9430 and a good lug than a TIG weld. Even if I could run a pretty solid bead, and I could bring the areas that have been annealed back up to something like a t3 or t4 with age hardening (which I'm guessing is a little optimistic, considering that it won't have any sort of proper solution treatment), its still probably not going to out perform a proper aerospace grade adhesive with good sheer strength in most applications, without at least a good ten or 15 years of wear.

I'm thinking that for now, maybe I'll do some "screwed and glued" aluminum frames and focus on getting the router finished, then maybe take a crack at building carbon fiber frames like you were suggesting, only maybe with prefabbed tubes and aluminum lugs instead of wrapping or vacuum bagging something myself, since I will have a little experience with a similar design, and the ability to run off custom lugs on the router at that point.

[iamsofunny]

I didn't heat treat my bike. It's good enough.
You can't really glue aluminum though. Maybe braze and fiber wrap after.

[Indubitably]

I didn't heat treat my bike. It's good enough.
You can't really glue aluminum though. Maybe braze and fiber wrap after.

I don't know, it seems to me like people have glued aluminum to great effect in the past with bikes, and it is certainly common practice among the DIY aircraft folks (not to mention the aircraft industry for that mater). Either way, it won't cost me much to try, so I'll let you know if it turns out to be a disaster, but I think it probably will be the most workable solution for me at this particular juncture. I do like the idea of wrapping light aluminum with fiber though. We really don't need to be nearly as weight conscious as the pure HPV folks, and a carbon-aluminum composite could be a convenient way to keep the bike affordable but still be very light and strong. Maybe I'll even throw a titanium ferule in the mix here and there to introduce a little spring in the frame where it makes the most impact, provided they can be sourced at a reasonable price.

[Indubitably]

So, apparently an ebike controller wouldn't really make sense as the inverter drive for a welding machine, but what about an induction heater? It seems to me that if you could target the ideal frequency for heating the filler metal instead of the base metal you could braze something like aluminum pretty easily (or at least much more easily than something that forces all kinds of oxidizing agents into the puddle just to get the thing hot in the first place).

I mean, yeah, obviously running off a bunch of frames by hand and then having them all solution hardened is going to be more versatile and cost effective if you are doing small production runs and know how to weld, but it might be easier and more effecive for some of us to do something like induction brazing for certain joints and then use a combination of bolting and or glueing or fiber rap for the rest.

At any rate, I found this website that goes into way more detail than I would have expected to find on the subject, and I figured it couldn't hurt to have a well documented example of a DIY guy building a fairly sophisticated induction heating system, so...

http://www.mindchallenger.com/inductionheater/

[Harold in CR]

Too off topic, so I started a new thread. Sorry

[iamsofunny]

6061 t6 is solution heat treated, precipitation treated and 'artificially aged' (400F for 1 hour baking).
Post weld treatment is the same thing, just bake at 400F for 1 hour.
The weld filler metal cannot gain any strength from this treatment because it's 4043 which only work hardens, sort of. In practice 4043 just kind of cracks when you bend it. But for filler metal it flows awesome at lower temperatures, does not get oxygen mixed in as easily as the 5356 and the strength is basically the same from my tests.

Any aluminum welding, except for the oxyfuel stuff, requires argon.

If you have enough money then I recommend you get the everlast tig 185, autodarkening helmet, get some argon and go for it.

You remind me of myself a few years ago trying to build bamboo boats in the Caribbean. It can't really be done because of bugs that eat the bamboo, but I tried many times.

[salty9]

Don't know if it can be used for TIG but alternators can be used for welding.
http://www.yachtwork.com/report-welder.htm