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Thread: brass brazing

  1. #1
    scottnotreally
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    brass brazing

    what wall thickness is desired for a brass fillet braze? is columbus spirit too thin?

  2. #2
    Framebuilder
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    The shaped Spirit with 5/3/5 walls? It's higher level stuff as far as fabrication, you have to really have your skill set refined to pull it off. If you're going to braze it, Fillet Pro (with it's lower working temp) is the way to go.
    Btw, like all the light weight materials, there is a rider weight limit for Spirit.
    Last edited by Live Wire; 10-07-10 at 02:01 PM.

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    Old fart JohnDThompson's Avatar
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    I remember Mike Appel built a fillet-brazed frame from Ishiwata Alpha tubing (also 5/3/5) and was able to ride it for several years before it failed.

    You're really pushing the limits with tubing that thin, even if you know what you're doing (which Mike certainly did). Is there a reason you don't want to use lugs?

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    Tell it as it is Silverbraze's Avatar
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    if you are asking the question
    you are not ready

    I ask, what value is there is using tubes .5/.38/.5 in your frame?
    100 to 150 grams !!!!!!!!!
    use .75 or .8 walls
    and have some crash resistance
    long life
    and also it will cope with your skills
    Harsh maybe be
    but the best path

    and I have never used .5/.38/.5 tubes in the main triangle as it serves no useful purpose
    it's steel
    it's lugs
    let the others get on with the madness
    www.llewellynbikes.com
    www.framebuilders.org

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    Randomhead
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    don't forget that there is Spirit for lugs, which isn't quite so thin as the shaped stuff.

    Quote Originally Posted by JohnDThompson View Post
    I remember Mike Appel built a fillet-brazed frame from Ishiwata Alpha tubing (also 5/3/5) and was able to ride it for several years before it failed.
    how and where did it fail? I've thought about building myself a bike with Spirit or TT S3, just because. I would use fillet pro, I assume Mike used brass.

  6. #6
    tuz
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    On frameforum I remember reading to stick to 0.7 mm and above for brass brazing.
    homebuilt commuter, mixte, road and track (+ Ryffranck road)
    bla bla blog

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    legalize bikes
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    i like to use .035" straight gauge cro-mo. dirt cheap and no worrying about butt length!

  8. #8
    Old fart JohnDThompson's Avatar
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    Quote Originally Posted by unterhausen View Post
    don't forget that there is Spirit for lugs, which isn't quite so thin as the shaped stuff.

    how and where did it fail? I've thought about building myself a bike with Spirit or TT S3, just because. I would use fillet pro, I assume Mike used brass.
    The down tube separated from the head tube.

    Yes, it was brass. Fillet Pro wasn't available back then.

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    "i like to use .035" straight gauge cro-mo."

    So do I, but that is kinda the other end of the spectrum. Which is what he should be thinking about...

    I got kicked off the other forum for suggesting it, but there is also .028 tubing for those who like what they see in the mirror.

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    Decrepit Member Scooper's Avatar
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    Schwinn built tens of thousands of fillet-brazed frames between 1938 and 1978, and used straight gauge 4130 chromoly tubing with pressed-in reinforcing sleeves at the joints to act as butting. The finished frames were strong and durable, and relatively light (my 61cm Super Sport frame weighs 7 pounds without headset, BB, or kickstand). The wall thickness of the tubing measures a hair over 1mm using a caliper.



    - Stan

  11. #11
    Framebuilder
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    I agree with everyhing you said except for:

    Quote Originally Posted by Silverbraze View Post
    never used .5/.38/.5 tubes in the main triangle as it serves no useful purpose
    It does have it's place and it can build into a super light, sweet riding frame...it will just have a finite lifespan if it's ridden by a strong and/or heavier (180#) rider.

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    I don't know if you have checked recently but 180 is the average weight of women these days, let alone men. If something has a finite lifespan that means it is working past yield (I'm just guessing here), that sounds kinda squishy to me. That doesn't mean it shouldn't be used, but I do wonder about it. Also sounds lkue a pretty poor fortress liability wise.

  13. #13
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    And the number of bikes built with Spirit tubes you've ridden is....?

    I agree with you on the lifespan issue though. I build bikes with longevity/durability in mind and never use anything thinner than 7/4/7 and that's been for women and little guys.
    I have, however, ridden/helped fab 5 different Spirit tubed bikes and they were great! Plenty stiff too.

    BTW- 180 average for women? Dude, you need to move to a different town!

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    meech151
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    As a new builder I get most all my knowledge either through trial and error or asking guys like yourself who have more experience. I have built 3-4 frames out of TT S3 luckily without issue yet, I only do fillet brazing, so if we have these thin walled tubes produced and sold that are clearly not for lugs how else can you join them other than fillet-braze with brass? I am not a tig-welder but I have been told that trying to tig this thin stuff is almost impossible and I would think it would damage the tube way more than brass. Also, I have heard of Fillet Pro although I haven't used it but it hasn't been around for as long as the ultra-thin tubing has it? I guess my question is how did the producers of these super-thin tubes intend for us to join them if they aren't made for lugs? Are the S3 frames that I've built just living with a limited lifespan because they are 6/4/6, are they gonna fail just for that reason? I can understand they may fail if they were joined improperly, overheating, etc. but are they gonna fail just because they are thin wall?

    Oh yeah, and those are some big girls you're hanging out with Peter Pan.
    Last edited by meech151; 10-08-10 at 06:02 PM.

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    Randomhead
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    Quote Originally Posted by Peterpan1 View Post
    If something has a finite lifespan that means it is working past yield (I'm just guessing here), that sounds kinda squishy to me.
    A fatigue failure does not mean that there are stresses that exceed the yield strength of the tubing. That's the misunderstanding that caused the Brits to lose all those Comet passenger jets back in the '50s, the airframe was built to accept a load far higher than it would ever see in service.

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    Thanks on the engineering!

    On the spirit tubing, I try not to use anything i can't get at home depot. I wish.

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    Senior Member Nessism's Avatar
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    Quote Originally Posted by Silverbraze View Post
    if you are asking the question
    you are not ready

    I ask, what value is there is using tubes .5/.38/.5 in your frame?
    100 to 150 grams !!!!!!!!!
    use .75 or .8 walls
    and have some crash resistance
    long life
    and also it will cope with your skills
    Harsh maybe be
    but the best path

    and I have never used .5/.38/.5 tubes in the main triangle as it serves no useful purpose
    Oh come now, TIG guys have had their way with killer thin tubes for years. Not my cup of tea either but that's not to say that you can't build a decent frame from the stuff. Old school ELOS and similar had .4mm center butts, and the metal used wasn't as hard as modern alloys so those frames dented really easily yet lots of people loved them.
    Last edited by Nessism; 10-08-10 at 10:44 PM.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  18. #18
    meech151
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    OK, fair enough. So if you exclude Fillet Pro, tig welders can tig it and fillet-brazers can use their brass, was there an intended method for joining these thin- walled tubes by the producers of them and just because they are thin-walled does this mean there lifespan is limited no matter how they are joined. If they are joined correctly and the rider weight limit is in effect why wouldn't the frame last? The S3 stuff rides pretty good. My road bike is all S3 and a buddy of mine is riding the first S3 cross frame that I built with no issues yet and he abuses it, granted hes only 140lbs and has only a little over a year on it. I guess I just don't want to believe that the frames I built out of thin-walled tubes are destined to fail.

  19. #19
    Framebuilder
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    Quote Originally Posted by meech151 View Post
    OK, fair enough. So if you exclude Fillet Pro, tig welders can tig it and fillet-brazers can use their brass, was there an intended method for joining these thin- walled tubes by the producers of them and just because they are thin-walled does this mean there lifespan is limited no matter how they are joined. If they are joined correctly and the rider weight limit is in effect why wouldn't the frame last? The S3 stuff rides pretty good. My road bike is all S3 and a buddy of mine is riding the first S3 cross frame that I built with no issues yet and he abuses it, granted hes only 140lbs and has only a little over a year on it. I guess I just don't want to believe that the frames I built out of thin-walled tubes are destined to fail.
    Depends on the intended application and the strength of the rider too. Strong riders seem to break more stuff then heavy ones do. But you're right, S3/Spirit can make a long lasting frame when used correctly.
    FWIW, I would never build someone my size (6'2" 190) a frame with tubes that thin.

  20. #20
    scottnotreally
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    thank you for the awesome answers. I havent brazed it yet just was curious. you guys are super awesome.

  21. #21
    meech151
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    Yeah, thats what I thought. I believe the rider weight limit on S3 is 190 but I would never use on someone over 180 just to play it safe. I am 6'2 and 165 and it feels pretty good to me. The first time I used it was for a racing buddy of mine and he just wanted to try it on a cross bike just to see what would happen, I cringed at the idea but it has held up thus far and I am hoping that it last forever, we'll see.

    Hey Live Wire I was checking out your blog and it looked like you had a little accident. How are you feeling? I would have told them to insert some bionics in my legs then we'll see how this thin stuff really holds up. Twist that stuff up like a Christmas ribbon.

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    Ouch, was the guy on his phone. I'd say the Doc putting in the screws did a pretty good job, my leg looks worse 10 years after being hit at 160 mph by a 20" tamarack tree.

    Speaking of light bikes. Been looking at this bike with seatstays made out of lightweight 3/8" 4130. Don't seem to give the builder any trouble, but that is some light tubes. I wonder what the

  23. #23
    Framebuilder
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    Thanks for the thoughts guys. It's getting better- I finally got clearance to put some weight on it this week, so I've been more mobile (w/a cane-my son says I look like Dr. House!)and being able to stand at the bench makes framework a lot easier. Still 6 weeks from being able to ride.
    No complants though. It could have easily been much, much worse, plus, now I have an excuse to build me a new mtb!

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    Have you talked to a lawyer? (no answer required).

  25. #25
    Tell it as it is Silverbraze's Avatar
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    Quote Originally Posted by Live Wire View Post
    I agree with everyhing you said except for:



    It does have it's place and it can build into a super light, sweet riding frame...it will just have a finite lifespan if it's ridden by a strong and/or heavier (180#) rider.
    Mitred for 54cm frame

    Spirit 31.7 TT .5/.38.5 = 168 g
    Spirit 38mm DT .5/.38/.5 = 220 g
    Spirit 28.6 ST .6/.38/.5 = 166 g
    Total main tubes = 554 g
    (the original .5mm CS tubes were removed from sale, did not meet with success in the real world, failures etc)

    Mitred for 54cm
    Life 31.7 TT .65/.4/.65 = 206 g
    Life 38 DT .65/.45/.65 = 264 g
    Life 28.6 ST .75/.4/.6 = 189 g
    Total main tubes = 668 g

    You save 114 g.
    Is that really making the frame "super light"?
    Selection on three tubes alone does not make a frame light.
    Select the other parts of the frame with a reliable reduction in grams is Ok to a point, but the three main tubes gain buggar all for a lot in the loss column.

    An empty 750mm plastic water bottle = 85 g

    I see no value on making a frame with the three main tubes thinner than .65/.4/.65, no matter what diameter.
    considering the consequences of some times simple crashes, not just TT dents fro handle bars but the main triangle crumple! (I have seen them)

    I see no value in the reduction of 114 grams even if you believe or perceive it has some performance benefit, and this is only a perception as it can not be measured because it cannot be measured in the real world. (I worked for many years with the Australian Institute of sport .....................)

    The value of light is in marketing brochure text.
    Last edited by Silverbraze; 10-24-10 at 05:15 PM.
    it's steel
    it's lugs
    let the others get on with the madness
    www.llewellynbikes.com
    www.framebuilders.org

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