Help on Bicycle Alloys--Bikes for Tykes

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I've welded for 40+ years and actually took courses years ago but have mostly been a stick  and gas welder.  Recently got more into TIG and have done lots of volunteer projects since on all metals and aluminum.  I'm fortunate enough to be able to retire and hope all you guys can do the same some day....On another board a guy who heads up a national "Bikes for Tykes" program does repairs on bikes which get sent out to kids across the country that can not afford them.  He recently bought a TIG unit in order to repair some of the broken bikes  they receive in and I suspect he will be having some difficulty as I would in identifying the many sophisticated alloys they use in bike manufacturer. He has not done much TIG work before and I offered to help get him started.Can any of you advise what would be a good filler rod to use that might be universal in it's application.  I normally use 4043 or 5356 for Aluminum but these bikes can be anything from moly steel to titanium I guess.  Is there a way to use a general rod for metallic and some others for non metallic frames?  This is where you expertscan help that have the ability to  identify the right filler rod to use.Any help would be appreciated....thx..jbman45Century 230A AC/DCLongevity 200 Multifunction MofsetLongevity 200PI Multifunction IGBTVictor Oxy/Weld&Cut5HP 2 stage compressorTractor; tools and 40  years of collecting fine tools.
Reply:I imagine Tyke size bikes  are plain ol' Mild Steel Or Aloominum- doubt the manufacturers spend any $$ on an Alloy.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:most aluminum bicycle frames are heat treated, not sure about tyke sized ones but that would be a good place to start for Al bikes. steel bikes even the cheap ones are made from a cro-moly based alloy, the lighter the frame gets the more chance for fancy and complex alloys. most professional frame builders will use good ol er70s-2 although some are starting to switch to a weld mold rod called 880-t.  i have used the stuff and it is nice but spendy, not something i would thing he would want to buy for what i am assuming is a non-profit. these may not be the absolute best filler choices but it will hopefully get you going in the right direction.
Reply:Thanks guys, really appreciate your comments and have a good start point at least.jbman45Century 230A AC/DCLongevity 200 Multifunction MofsetLongevity 200PI Multifunction IGBTVictor Oxy/Weld&Cut5HP 2 stage compressorTractor; tools and 40  years of collecting fine tools.
Reply:Have a look on these sites for dedicated bicycle aluminum tubes.http://www.columbustubi.com/index.htmYou could also have a look for Easton bike frames and Tent poleshttp://www.dedacciai.net/andhttp://www.reynoldstechnology.biz/orhttp://www.bikepro.com/products/metals/alum.htmlwill have your reading for a while.Exotic alloys and heat  treatment.Last edited by ElGuapo; 09-24-2009 at 02:21 PM.
Reply:I cut up a lot of thrift store bicycles for homebuilt recumbents. Most are made from simple mild steel (not chromo or aluminum). Chromo is way too expensive to use in cheap bikes. The homebuilders I hang out with at www.atomiczombie.com will tell you the same thing. I occasionally do find a chromo frame, which I save for those special occassions when I need lightweight (thin) tube. We often use simple EMT from Home Depot when we just need a tube or two. It works fine as long as you deal with the galvanizing. If you want to know about scavenging bikes and bikes parts on the cheap the above site is very helpful.Last edited by smyrna5; 09-24-2009 at 04:39 PM.Lincoln 175HD Miller AC/DC ThunderboltSmith AW1, Dillion (Henrob) Mark III, & Smith LittleTorch
Reply:Steel frame = ER70-S2. Good for mild steel to chro-moly. I can't imagine any aluminum frame bikes making it to "bikes for tykes". But if so, 4043 (preferred), or 5356. Keep up the good work. "SOUTHPAW" A wise person learns from another persons mistakes;A smart person learns from their own mistakes;But, a stupid person.............never learns.
Reply:Originally Posted by smyrna5I cut up a lot of thrift store bicycles for homebuilt recumbents. Most are made from simple mild steel (not chromo or aluminum). Chromo is way too expensive to use in cheap bikes. The homebuilders I hang out with at www.atomiczombie.com will tell you the same thing. I occasionally do find a chromo frame, which I save for those special occassions when I need lightweight (thin) tube. We often use simple EMT from Home Depot when we just need a tube or two. It works fine as long as you deal with the galvanizing. If you want to know about scavenging bikes and bikes parts on the cheap the above site is very helpful.
Reply:Hmm, I don't know of a test to tell what sort of alloy you are using, at least not an affordable one.  I do imagine that trying a few different types of filler on the bike might give you a good idea on what steps to take next.I am a bicycling enthusiast.  Not only is it a very cheap method of transportation, but it is a great work out and that seems so vital.  Part of the reason why I am getting into TIG welding is in hopes to fabricate bicycles.  I went into every bicycle shop I could find and spoke with every shop owner I could, the American bicycle producer is -extremely- rare.I remember a few winters ago, I was riding to and from work, about an hour on bicycle.  Every day I would arrive sweaty and ready.  Unfortunately that job was a freakin desk job.  By lunch I'd be ready for a nap, it wasn't uncommon for me to begin to pass out at my desk.  I couldn't wait to get out of there and onto my bicycle.Miller 330 a/bp water cooledI believe in gun control, I hold my gun with two hands.  If you want to know why, click here.Buy American or bye America.
Reply:Originally Posted by RojodiabloYou can't be serious about using EMT for a bike frame, can you?? I do not mean to be disrespectful, but that stuff is like the hot-dog of the welding world. All the lips, snouts, hooves and arses get ground into that metal. It's the lowest quality stuff ever, and not really any kind of a good choice. It's very soft, and made to be bent and shaped with no regard for strength. Even Huffy won't use it, it's THAT bad!!
Reply:As said, an er70 type filler will be fine for steel/alloy steel frames. Some builders like a stronger or disimilar (312 stainless or a variant of) filler but that's the same debate that constantly crops up with 4130 tube chassis... The cheaper aluminium frames are typically made from 7005-T4 (naturally aged) although some manufacturers artificially age (something like 6 hours @ 90-100*C followed by 4 @ 150-160*C) 'higher end' frames for better properties/less weight. 7xxx series alloys are welded with a 5xxx series filler (5180, 5356, 5183). Proprietary 7xxx series alloys would be welded the same way but PWHT would vary. Not likely to come across many of these types of frame in a bikes for tykes scheme though, probably for the best as they've had every bit of excess engineered out of them and are best not repaired imo6061, close relatives and proprietary 6xxx series are typically found on more expensive, higher end bikes only as it's virtually always tempered to T6 condition (solution heat, quench and artifical age) after fabrication.Very much doubt you'll see any Ti frames but FWIW grade 9 (3Al/2.5V) or grade 5 (6Al/4V) are used with some 'braze on' fittings made from grade 2 (commercially pure). Can be welded with a matching, undermatched or grade 2 filler depending on desired properties
Reply:Originally Posted by RojodiabloYou can't be serious about using EMT for a bike frame, can you?? I do not mean to be disrespectful, but that stuff is like the hot-dog of the welding world. All the lips, snouts, hooves and arses get ground into that metal. It's the lowest quality stuff ever, and not really any kind of a good choice. It's very soft, and made to be bent and shaped with no regard for strength. Even Huffy won't use it, it's THAT bad!!
Reply:Originally Posted by quasihe is building recumbents though, they are the circus clowns of the bike world. and the fact that he is building his own means he is that much more out their. EMT would be fine you just need to use twice as much of it as you would with DOM
Reply:Originally Posted by smyrna5Yeah too bad the non-circus clown bike riders could not beat the 4 man recumbent teams (several of them sort of plump middle-aged guys) on Bacchettas and RANS in the 2008 and 2009  Race Accross America. (Coast to coast at an average speed of 20+mph). Not build from EMT, of course.http://www.ransbikes.com/ITR79.htmMY bikes are not that fast (bad engine) but my butts not sore after 100 miles either.  See ya next year - its open to wedgies too
Reply:Originally Posted by WeldordieGreetings, smyrna5... I built my first LWB bent about 30 years ago out of EMT, welded together with O/A and bailing wire.  The frame is still structurally sound after thousands of miles... nary a failed weld.  Don't you just love it when someone says you can't do something a certain way?  I've found it usually reveals someone that has little or no experiance in the area, and/or someone who can't think out of the box.
Reply:here is another question, how many broken bikes is he really coming across? i spent some time durning and after high school working in bike shops and haven't seen a ton of broken bikes. certainly not enough of them to warrant buying a high dollar tig machine