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  1. #1
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    I want to add my own braze-ons to steel frame

    The frame is an '81 Centurion with Tange Champion #5 tubing. From what I've read it is straight gage. I want to add cable stops, bottle mounts, and rack mounts if I can do it myself. I have access to an oxy-acetylene torch and have knowledge in metallurgy/mechanical engineering. What do I need to do this?

  2. #2
    I ride my bike Revtor's Avatar
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    brazing rods, flux, and a way to strip the paint off the frame. and most importantly an old frame to practice on!

    have fun

  3. #3
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    Can you recommend any brazing rod/flux?

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    Personally I would use 45% silver and whatever flux goes with it. I use the Harris stuff, though the swells seem to use something different.

    Once you have the raw materials all cleaned up you have to position the bike so that the BO will be in a proper position with gravity alone. If the object doesn't have sufficient weight, consider using a piece of bent coat hanger that is shaped like a staple. Make it so it's weight will hold the piece in place when hung over the BO. other options are to lie the bike down and put something non-flamable under the frame tha will support the BO at the right leve. Or build up a parallel tower and rest something over the top so it presses down on the BO and the tower. You can even wire some parts on, but braze will tend to weld the wire down, try chalking it up that may stop stuff attaching. Even so the wire can sometimes wick flux braze to places with threads etc...

    You want a small jet and you want to set the flame so it is quiet, just heat the part up until the flux melts and then some bubbles come up, then add the silver, it will go in by itself when it is ready you can't force it. With a Oxy torch you need to work all sides of the part, and touch the parts with the flame, then lift it off. It will overheat everything if in constant contact.

  5. #5
    Faith-Vigilance-Service Patriot's Avatar
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    Peterpan1,

    Do you use regular silver solder for simple braze-ons, like that used on copper piping, etc?

    I have some stronger silphos brazing wire, which may be stronger, but for my project adding some bottle bosses, der cable stop, and seat stay eyelet inserts for a rack may not need the extra strength. Plain silver solder is so much easier to work with. The silphos brazing stuff needs to get so hot, I'm concerned about loosing the stay/seat tube braze connection when I do the eyelets for the rack. The eyelets are only a couple inches away.
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    If you're brazing small parts on like cable stops, just be careful not to overheat the parts. It isn't real difficult, just need to be careful with the heat. I brazed cantilever studs on my Klunker with a mapgas torch from Home Depot and they have held up fine.
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  7. #7
    Faith-Vigilance-Service Patriot's Avatar
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    ^^^ I assume you used brazing wire, instead of silver solder?

    Would silver solder hold for a front der cable stop?

    I assume so, since I recently read an article on bike building, that Schwinn used alot of silver solder for less stressed parts (bosses, der stops, guides, etc) on most of their bikes back in the 70's and 80's.
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    You probably "can't" overheat the parts since most of the BOs are just mild steel or even chromo. It's pretty hard to harden them without quenching which you shouldn't do. YOu can occasionally get a circumstance where quenching occurs naturaly via a breeze, etc... If you are worried try dressing them up with a file and if it cuts well you are fine.

    It's actually easier to burn them with a MAPP torch or a propane torch. You have to heat, heat, heat, heat, heat, and by the time it is up to heat, a lot of stuff has soaked up heat and flux may have burned up etc... With oxy, if you let the torch sit, it could melt the steel into a puddle, SO it just takes a few flicks to get everything up to speed. With BO it's fine to use the little torches, but for larger jobs where you have to keep moving you will end up laying down over dirty stuff the torch burned, and it is pretty hard to do a really good job.

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    FWIW, I used 56% silver wire when I did the braze-ons for the frame I built. I did some with an Oxy-acetylene torch and some with a cheap Home Depot Oxy-Mapp torch.

    Coat everything with flux, then start heating the area up slowly. The flux I used bubbles when initially heated. Then it gets a bit crusty. As you keep heating it, it will start to become transparent; a sort of "watery" or "glassy" look. At that point, you can add add the silver. It's important to get the entire area hot, but not too hot. If the tubes, or more likely the braze-on, get red hot you need to pull the torch away immediately! If not, you'll end up burning the flux and you'll have to start over. I found it best to keep the torch moving, not heating any one area for too long. Once you've got some silver on the joint, you can use the torch to kinda pull it to wherever you want it, though you can't work miracles. Try not to add too much silver at once; it will have a tendency to run all over the place, including places where you don't want it.

    I would encourage you to practice on some old tubing before working on your own bike. It also helps if you can have someone with experience watching while you do the first one or two.

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    I found some Harris 15 brazing rod at work. I use it all the time. Works good. Not sure if it's best for this thoguh.

    Here's the specs:

    Melting Point- 1680 F (882 C)
    Working Temperature- 1600-1720 F(871-938 C)
    Tensile Strength- 60,000-65,000 psi
    Brinell Hardness- 80-90
    Machinability- Excellent

    Is this stuff too much?

    The cable stop I want to add is close to the BB shell. I don't want to overheat it when brazing and have my BB fall apart. Of course that requires even more heat. I'm not sure what they used on this bike to begin with. I could also use my small torch head.

    Would using cheap tin solder be enough to hold some bottle bosses in the holes?
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    The melting temp of that stuff is above red for steel. So if you are sucking it in by heating the steel and allowing that to heat the braze you are going to have some glowing parts before anything happens. With a lot of materials that isn't actually a problem, brazing frames together does require getting the parts red hot. Though not being silver, which is a choice, the preference would be an unfluxed rod and flux, is that what this is? If so you are good to start playing.

    I should add that "red hot" is visible in half light, not bright light or the light of a lot of video production. The forge was normally a fairly dark place lit by the light of the fire. Seeing the various colours is best done in the kind of light one gets at dusk, however caused.

  12. #12
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    Why not just do it the right way?

    You don't need a lot of heat to ruin a braze-on; they don't have a lot of mass so they'll heat up very quickly. You want to use a thin wire, not a brazing rod. It's easier to control the amount of silver added, as well as the heat.

    Anyway, buy some flux and some 56% silver wire. I used 1/32" cadmium-free wire. Find a welding shop that will sell you 5-6 feet for a couple of bucks; I ended up buying an entire Troy ounce, which was expensive. Hell, send me a self-addressed stamped envelope and I'll send you enough wire to do 2-3 bikes.

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    The point is that heating them up doesn't ruin anything. at least not to the temps involved for any of these materials. A lot of people are getting them red hot or they just don't know what red hot is. There was a thread a while back about a video of a Japanese frame builder who was brazing his tubes, which is a different mater. It drew a fair amount of coment until some old pros jumped in and said that was how hot it should be. You should always use the least heat you can, but there are misconceptions across the board about how much that is or what it is doing to the tubes. If nothing else, cooler is often less clean-up.

  14. #14
    Senior Member Nessism's Avatar
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    I agree on using 56% silver for braze-ons - it flows easily and is low temp which is good for a newbie brazer. Many builders using brass for the joints (high temp) use silver for the braze-ons.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

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    Quote Originally Posted by Peterpan1 View Post
    Personally I would use 45% silver and whatever flux goes with it. I use the Harris stuff, though the swells seem to use something different.

    Once you have the raw materials all cleaned up you have to position the bike so that the BO will be in a proper position with gravity alone. If the object doesn't have sufficient weight, consider using a piece of bent coat hanger that is shaped like a staple. Make it so it's weight will hold the piece in place when hung over the BO. other options are to lie the bike down and put something non-flamable under the frame tha will support the BO at the right leve. Or build up a parallel tower and rest something over the top so it presses down on the BO and the tower. You can even wire some parts on, but braze will tend to weld the wire down, try chalking it up that may stop stuff attaching. Even so the wire can sometimes wick flux braze to places with threads etc...

    You want a small jet and you want to set the flame so it is quiet, just heat the part up until the flux melts and then some bubbles come up, then add the silver, it will go in by itself when it is ready you can't force it. With a Oxy torch you need to work all sides of the part, and touch the parts with the flame, then lift it off. It will overheat everything if in constant contact.
    What do you do with BOs that won't sit still with gravity alone, like cable stops on the top tub that are bullets with a slot in them? or rear rack mounts that go on the seatstays?

    Also does anyone have a drilling jig for drilling the water bottle bosses they would rent?

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    Quote Originally Posted by ACH57 View Post
    What do you do with BOs that won't sit still with gravity alone, like cable stops on the top tub that are bullets with a slot in them? or rear rack mounts that go on the seatstays?
    Take a look at the Braze On Jig that Henry James sells. I think there are pictures in their Tech Info PDF. Once you've seen it, you should easily be able to build your own. You can probably find a few other designs on the web, too.

    For cable stops, you can do what I do: cut a piece of thick welding wire 12-18" long, clamp it to a tube, and slip the other end into your cable stop. This will provide just enough downward pressure to keep the cable stop in place and the clamp will be far enough away that it won't melt.

    Also does anyone have a drilling jig for drilling the water bottle bosses they would rent?
    Is there such a thing? I just took a bottle cage, duct taped it to the appropriate tube, then used a transfer punch to mark the center of each mounting hole. Gave 'em a light tap with a center punch, then drilled the holes using a cordless drill and a steady hand. Of course, the True Temper Versus tubing I used wasn't that difficult to drill. If you're working with harder tubing, you might want to use a drill press or mill to drill the holes. In any event, this is one of those places where I think you don't need supreme accuracy. There's enough slop in the mounting holes for most bottle cages that you can be off by a few millimeters and it won't be a problem...

  17. #17
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    Quote Originally Posted by sstorkel View Post
    Is there such a thing?
    Nova has one for $140...

  18. #18
    Senior Member stokessd's Avatar
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    You can make your own drill guide out of wood (with a V groove) and a couple drill bushings. Frankly, I'd do the center punch and drill method.

    Sheldon

  19. #19
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    FLIPPIN' FLUX!!!

    I got me a small spool of Silv-56. Spent a whopping $28 for it. The cheapest they had. Not happy.

    Then I was at work and started on the job. I shortly realized, the all purpose flux I had, was not working. I come to find out, the special flux for Silv-56 is the best.

    To heck with that. Tossed the Silv-56 back into the bag. Then, I grabbed a piece of pre-flux brazing rod, cranked up that MAPP, and went to town.

    BOSSES INSTALLED!!!!


    I should've said to heck with that expensive silver stuff to begin with.


    P.S. Anybody want to buy a small spool of Safety-Silv 56 for say... $10 plus ship? I barely used any. Maybe 2-3 inches.
    Last edited by Patriot; 07-04-08 at 04:13 PM.
    President, OCP
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  20. #20
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    Quote Originally Posted by Patriot View Post
    I should've said to heck with that expensive silver stuff to begin with.
    No, you should have bought the silver stuff on-line (for $11 less) and paired it with $4 worth of the right flux...

  21. #21
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    ^^^ No, I could have spent $0, and just used the brazing rod I already had to begin with.

    I'll keep the Silv, Who knows, I may just use it for a future build.
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  22. #22
    Senior Member joseph senger's Avatar
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    hey peter, hope everything is going smoothly

    I just wanted to pipe in here. I'm pretty darn sure I know the video you were discussing up on this thread. I was recently in an "alley cat" race, and of course, in alley cat fashion, a bar is the final destination. Started talking to this french fellow about his... lugged schwinn (the name escapes me), a rare ride here. Anyways started talking about frame building, he has a tube set at home for the last 5 or so years, ordered on a moment of... and owning no tools, torche, etc... it has just sat. But him and his brother start talking about njs bikes. Long story short, I go outside to leave, his brother came after we had went in, and he goes to show me this this "njs" track bike he is riding, and low and behold there sit a candy red and blue speckled (nice speckle to say the least, im usually not a fan) Leve_/ frame. My jaw dropped; all the time i spent studying the documentary, i never thought id see one in town, let alone be urged to hop on and ride. The one thing i notice immediately were the extremely thin lugs, and the owner mentioned that is was chromed under the paint.

    anyways, I've built two frames now. It was really amazing that learning curve on the first one. To any of you reading this, I pestered peter about some of the most trite (now in retrospect) matters, but he always gave me his honest and informative opinion, atmo (hehe). It really is a matter of just getting to work, and practicing on old stuff. Braze ons are easy in the whole scheme of things, but you can burn that white flux pretty quick (which is ok is it happens AFTER the silver is in), for the newbie see if you can get harris brown style flux, very hard to burn. 45% silver is minimum, copper pipe silver i think has less than 10% and is mostly tin, and imo a zap strap holding the braze on may be comparable to it. a #0 victor tip works well for brazeons, get the fuel flame to just before it is clean (no smoke), and add the o2 until there is a secondary cone about 5mm in protrusion. Keep the flame back about 5-8cm, and keep it moving. You want to heat the hole area until it is "wet" looking then localize the heat at the top (use gravity if you can) of the BO and pull it down with the flame. You know after if you are too hot, the silver will burn off some of its copper (i think) and will look more like a light brass. Also, an option if you live somewhere and it seems like you just can't get silver there, im fairly sure almost every hardware store sells those, i think benzomatic or something like that, blue rods. They are a nickel and copper mix if i remember, some guys (paterek) fillet with a similar material. They may be worth a shot in the event of simply wanting to put on a few braze ons and not spendy 50 bucks ordering silver and flux. I must warn you however, melting point is around the 1600 mark, there only advantage over brass is there increased viscosity. I must add I have never used these pre fluxed rods, however the alloy, as HJ sells it, must be good for something.

    ok peter, I leave tomorrow on my bicycle to alaska. I will try and shoot you some pics of the bike im taking, my first frame, and if not before i leave, when i get back. Have a good summer, and I will look to the sky every now and then for an outlaw flying a chair doing aerobatics.

    oh, here is a link which is a partial build sequence of the second, fillet brazed, frame. http://www.flickr.com/photos/21493845@N08/
    Last edited by joseph senger; 07-03-08 at 01:25 PM.

  23. #23
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    Joseph,

    fair winds. Glad to know you leaned into the learning curve and swept on through. I've been working on some tooling recently, and hope to get to work on my Rohloff frame someday. I've totally put the airchairs on long term hold, if ever. I have a 24 foot trimaran I would like to get in the water in late summer, going to be busy.

    Look forward to seeing the pics. Here is a pic of some of the small tooling, a saw holder for my mill, and some dies for the rack bender. Also a "small" stash of 46% silver.

    Hmm. don't see the browse attachments feature, so I guess photos will have to wait.

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    I got all of my braze-ons installed. Thanks for all the tips. It was easier than I expected. Not really any harder than soldering copper pipes except that it all heats up faster with the acetylene torch. I used 56% silver wire and Harris flux.

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