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Thread: Pinning

  1. #1
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    Pinning

    how is this done?

    From looking at the progess photos on the Jonny Cycles website, it looks like he uses small nails. Im guessing his process is, set the joint up on his jig, drill a hole slightly smaller dia. than the pin (nail), drive the pin, transfer the frame to brazing stand,vise etc.. for brazing. then cut the pin down and file smooth when finishing the joint.

    Anybody care to correct me? or add something I'm missing?

  2. #2
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    Quote Originally Posted by white folks View Post
    how is this done?

    From looking at the progess photos on the Jonny Cycles website, it looks like he uses small nails. Im guessing his process is, set the joint up on his jig, drill a hole slightly smaller dia. than the pin (nail), drive the pin, transfer the frame to brazing stand,vise etc.. for brazing. then cut the pin down and file smooth when finishing the joint.

    Anybody care to correct me? or add something I'm missing?
    That's pretty much it- a very straightforward process and a good way to maintain alignment, like when you're replacing a bottom bracket
    I'll add that it helps to file a taper on the nail..... and don't use galvanized ones!
    Last edited by Live Wire; 11-13-08 at 11:26 AM.

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    taper-good info, thanks. any particular nail type? I was thinking a finishing brad till I looked at one and seen they were kinda square on the shaft part.

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    frequently one will pin the lugs, then align the frame.
    then- disassemble, flux, reassemble, braze

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    i plan on doing it much like that, pin and align main triangle, then align, pin, disassemble flux re-pin and braze

  6. #6
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    I do have some question in my mind as to what is a reasonable amount of flux, I have read to flux only where you want filler rod to go, but many pictures i've seen have the whole lug and an inch or two coated

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    Quote Originally Posted by white folks View Post
    I do have some question in my mind as to what is a reasonable amount of flux, I have read to flux only where you want filler rod to go, but many pictures i've seen have the whole lug and an inch or two coated
    Fux everywhere the flame will hit, and a little beyond, just in case.
    And for pins, 4D finish nails and a #51 (.067", I think) bit work great.

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    cool thanks for the tip(s) I'll report back after I get it all together.

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    Senior Member Nessism's Avatar
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    When I build a frame (without a fixture/jig), I pin the lugs/tubes and then pull everything back apart for fluxing. Slather liberal amount of flux on everything and then drive the nails back in. Last step is checking alignment and tweaking as needed before brazing.

    I do one joint at a time and make sure it’s perfect before adding each additional tube. This method is not ideal since heat causes distortion each time so I wind up doing unnecessary alignment bending this way. Despite this downside, this technique works well enough and the frame turns out straight. Needless to say, you need a surface plate to measure against. I made my own from a slab of steel with a pedestal in the edge which holds the frames bottom bracket – so the main frame tubes are parallel to the surface.

    Good luck and hope this helps.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

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    I pretty much did what you describe Nessism, I had a bunch of adjusting to do to the chain stay ports on the BB, they were at a different angle ("road" angles) and my chain stays begin to go oval right away so the tips of the lugs required some work with a brass drift and some 1/2" drive sockets. After that was all nice and tight, I lined it all up the best i could with my string and machinists rule and set the pins. Then I disassembled, fluxed and reassembled and did another string check. It seemed to hold it's alignment when I pinned it. I did the DT first, then the ST. By that time I had made a fine mess, overheating one section. I think the DT fit too snug, I just couldnt get filler to flow in one small area. I have gone back from the inside and added more filler but I'm kinda bummed how that went. But i seemed to have learned something, as the chainstays went really well, the flux went nice and glassy and the filler was sucked right in. Overall I'm happy, I learned a whole lot, didn't get hurt or burn anything i wasn't supposed to. I'm still grinning. I also have way more appreciation for pros, their pics of post braze joints where the flux is all glassy and filler only where it belongs, far cry from my bits of burnt flux floating in glass green goo and filler EVERYWHERE!!. I think theres a lug under there .

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    You can pull excess filler into the joints, or brush it off with a fluxed steel brush.

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    the filler goes where the heat is. If you are heating a tube and the lug/fitting is cooler, the brazing material will flow out onto the tube. I've heard the main problem that beginners have is holding the torch still. But pretty much you want to keep the flame on the lug and flit it out onto the tube enough that the tube stays hot. You are multitasking, you want the areas that you are moving to next to be hot enough when you get there.

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    peterpan1, that would probably save me 2-3 days of filing how does one go about doing that. I read brush it off with a fluxed steel brush and I think, flux a small steel brush with hi temp flux, heat the "afflicted" area and brush the filler away. I probabaly went through 3 rods total, when 2 1/2 would have done the job fine.

    unterhausen, It seems like the problem I had, or rather the issue I was unaware i would face I that when I cooked (overheated) the flux the filler did not flow like it would were flux present, Some areas were ok, as I applied the flux very liberally some excess would ooze right in to where i needed it. By the end , or rather by the chain stays, I had enough of a grip on getting the heat on the right spot (like you mentioned, mostly lug and a bit of wrist roll out to the tube) so it was like a reverse TiG, the filler chasing the flame. Also I think thats my biggest problem, knowing when and where to add filler. Sometimes I'd add when it was too hot FWWT where did the filler go? and sometimes too cool, and have to go back with the heat and coax it in.

    I'm learning a lot here. thank you gents kindly.

  14. #14
    Senior Member Nessism's Avatar
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    One of the keys to making a good brazed joint is to get the entire lug to a uniform temperature. To do this you need to keep the flame moving and preheat the lug on all sides – the lug with be the proper temperature when the flux gets all liquid and starts to bubble. After the lug is heated, add filler at the top so you can use gravity to your advantage. The filler will follow the heat but it also wants to flow downhill like any liquid. I do all my brazing in a bike stand so the frame can be positioned and moved around. Start feeding in the filler in at the top of the joint and sort of draw it down and sideways using the flame. Watch for the filler to come out the bottom to assure you have 100% penetration. Move the frame into different positions as you work your way around the joint. If the flux starts to burn, you are in trouble since the filler won’t flow. Keep the flame moving and don’t over heat the metal so the flux will last.

    Last step in finishing the joint is to drag the remaining filler still outside the joint inside, it will puddle inside the pipe joint where you don’t have to see it. If you have way too much filler, use a wire brush as suggested.

    To remove the flux, soak the frame in hot water. This step is critical to remove the flux inside the tubes. Flux is acidic and you really need to get it all out from inside the joint or you could have problems down the road.

    Regarding the original topic of pinning, I build frames one tube at a time and recommend this method to people without a frame fixture. For example, plug the seat tube into the bottom bracket shell, pin, align, braze, and check alignment again. If you go one joint at a time, it’s easy to align the frame before adding each new tube. If you just braze everything in one fell swoop (like some pro’s do), you need to make sure the frame in pinned very solidly and in perfect alignment before brazing (good luck doing that with strings and a straight edge).
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  15. #15
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    nessism, I see how "pre" heating the whole lug socket is needed, I did not do this on my first go around on the first tube, just kinda went at it...eek. Then I saw how much easier and faster the filler flowed when there was already some heat in it. Between the stuff you guys have told me and what I have seen, I imagine my next attempt will go much smoother. I have since gone back and cleaned it up quite a bit. Heated the whole BB with a deep red, then went around to the problem areas, careful to heat the lug where the end of the tube went, and as you folks said it drew in the idle filler, I did add more rod to two areas that seemed to "dry up" .

    Is it bad to go back and do this again? some of the lug edges have a pronounced sink/swell that i don't like. Whats your opinion on this? obviously it would be better to get it right the first time

    I am however very happy with the alignment. Non drive stays were "in" about 2mm and the other was very nice. After a tweak with a section of oak bannister I scavenged, it's as straight as I can do at the moment.

    I was gonna ask what you thought of my idea for alignment table. I have a 2.5'x3.5' chunk of granite countertop. I plan on doing up a dial indicator attached to a heavy base of some sort, but would like your opinion on the type (overall travel, graduation)

    thanks for all your help.

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