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  1. #1
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    Considering a Build Need Some Advice

    so im considering doing a bamboo/carbon build I want to make a cyclocross bike to use for winter. My first and biggest questions is how do you make sure the alignment is correct I know that if i dont know for sure and just eyeball it i will always think the BB is tilted, drops outs incorrect, ect. and it would drive me nuts. also is bamboo good for winter/rain bike? I would think it is. And what do you think the cost would be for product (not talking about groupset, wheelset, ect)

    I am pretty good with my hands and i thikn i could do good at this but it would be my first and i deffinitly need some help

  2. #2
    Andrew R Stewart Andrew R Stewart's Avatar
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    There are aspects of bamboo/carbon building that are different from metals but the basic issues are pretty much the same. Before the joints are completely formed/brazed, and are still able to be "moved", the frame (or sub sections) need to be checked for alignment. One alignment reference is that the head tube-seat tube are parallel, the BB shell centered and square and the rear axle also centered and square. (the other alignment reference is that the angles and tube lengths of the finished frame match the design). This "moving to alignment" is often done with the frame/sub sections placed on a known flat reference surface. Then measurements are done to tube centerlines and the tubes prodded into proper place. The surface is usually the flattest and most stable that you can access. True machinist's stone or metal surface plates, stone or other counter tops, table saw tops, milling machine tables are some of the surfaces that others have used. But don't discount the ability of a good eye to also work. With metal tubes of consistant diameters one's eye works well enough, with the uneven nature of bamboo... Many thousands (maybe millions) of frames have been built, with good enough alignment, with only reference wheels, straight edges and trained eyes. I can follow up with more details if you wish. Andy.

  3. #3
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    Quote Originally Posted by Andrew R Stewar View Post
    There are aspects of bamboo/carbon building that are different from metals but the basic issues are pretty much the same. Before the joints are completely formed/brazed, and are still able to be "moved", the frame (or sub sections) need to be checked for alignment. One alignment reference is that the head tube-seat tube are parallel, the BB shell centered and square and the rear axle also centered and square. (the other alignment reference is that the angles and tube lengths of the finished frame match the design). This "moving to alignment" is often done with the frame/sub sections placed on a known flat reference surface. Then measurements are done to tube centerlines and the tubes prodded into proper place. The surface is usually the flattest and most stable that you can access. True machinist's stone or metal surface plates, stone or other counter tops, table saw tops, milling machine tables are some of the surfaces that others have used. But don't discount the ability of a good eye to also work. With metal tubes of consistant diameters one's eye works well enough, with the uneven nature of bamboo... Many thousands (maybe millions) of frames have been built, with good enough alignment, with only reference wheels, straight edges and trained eyes. I can follow up with more details if you wish. Andy.
    Thanks ill take all the details you can give or if you know of a previous thread that has the details in it. thank you the help

  4. #4
    Andrew R Stewart Andrew R Stewart's Avatar
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    I don't know of threads in this forum about simple alignment methods so here goes.

    Taking the issue of bamboos inconsistant wall thickness aside and pretending it has the nature of metal tubing dimensionally...

    First insure that your Bb shell has square ends. Do this with a machinist square placed on the shell's end with the blade running along the shell's length. Do this at least at 3 or 4 different points around the shell's circumfrence. By filing the shell's end here or there you can get the whole end's face pretty square with it's length. BTW you can also face the head tube this way.

    Then you can use a straight edge placed on the shell's end and running along the seat tube (or DT) and measure from the straight edge to the tube's surface to make the tube square with the shell. Repeate on the other end. You can also devise a simple stand off from the straight edge to support the tube while the joint is dealt with, see attached photo.

    If both the ST and DT are square with the post then making the HT parallel with the ST is next. A simple method for this is to just sight along the HT to the ST watching the sides of the tubes relate to each other. Or sight the gap between the left side of the ST and the right side of the HT. Having a bright backround helps. (One of the great English builders used a wndow as the backround). By moving your head slightly from side to side you can see how the ST and HT line up and nudge the Ht into parallel with the ST. When building with metal tubes this is done after tacking so that the nudged reposition tends to stay there.

    Once the HT and ST are parallel (and the DT and ST are square with the shell meaning that the HT is centered with the shell) the TT can be placed. It doesn't really matter if the TT is parallel with any thing. It is nice to have both it's ends on center with the ST and HT but not needed as far as alignment goes.

    With metal tubes one way to do all this is to build with two sub sections that combine or hinge together to form the main triangle. The ST-shell-DT is one section. The TT-HT is the other. You can draw a full scale drafting that serves to insure the tube to tube angle as well as the tube lengths. Miter all to length and angle, set up to insure all is on spec. then join the ST and DT (with straight edge) to shell. Now you have half of the main triangle. Join the TT and HT to spec and the other half of the trialgle is done. Now when the two halves are put together you only have two joints to deal with. If you're using tubes you could tack the two joints and then align the HT and ST parallel before fully brazing the two joints. This is called the Hockey Stick way. The TT/HT section looks like a hockey stick.

    I've made many references to metal tubes. Bamboo and it's joining method is different and you'll have to figure out how to replicate the tacking of metal tubes. I can think of a way but I won't tell you how to bond bamboo, that's your bag.

    I'll discribe the rear triangle and fork (not that you're likely to build a Bamboo fork but this discription holds for metal too) in another post. this one is getting a bit long. Andy.
    Attached Images Attached Images

  5. #5
    Andrew R Stewart Andrew R Stewart's Avatar
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    Round 2- Rear and forks.

    So assuming that the main triangle looks good enough to continue the next, and bigger according to some, challenge is to build the rear triangle with the rear wheel properly located. Since many of the set up issues are the same for a fork build and I only have a fork conviently at hand in my shop tonight i will attach photos of a fork but talk about both.

    The rear triangle is easily designed with a full scale drawing. from this Chain Stay and Seat Stay lengths (and the shell to point along the Seat Tube that the SS intersect) are determined. CS are joined to the drop outs, mitered to length and fitted to the shell. The CS set up involves a bench vice, tube clamp, Cee clamp, good wheel and string. The DT is clamped in a tube block in the bench vice. This allows a few axises of movement of the frame and the ability to lock the final position in place. The CS are fitted to the shell (with a lugged shell this is simplely insertion, with bamboo or filets more clamping might be needed). A wheel is placed in t the dropouts. The wheel is clamped to the bench top. the frame is moved around in the vice jaws and vice base swivelling so that the wheel sits in line with the m

  6. #6
    Andrew R Stewart Andrew R Stewart's Avatar
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    I lost about 30 minutes of typing with a miss placed finger stroke. You guys are good at typing but not building... I'm not. I will finish this after the weekend. I need to pack for a trip now. Andy.

  7. #7
    tuz
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    Thanks to Andrew for taking the time to write this. Sticky material IMO.
    homebuilt commuter, mixte, road and track (+ Ryffranck road)
    bla bla blog

  8. #8
    Andrew R Stewart Andrew R Stewart's Avatar
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    IMG_1062.jpgIMG_1064.jpgIMG_1065.jpgIMG_1063.jpgRound 2 do over- back form a trip to my past life and now to complete what I started-

    OK so i now have shot a photo of the rear frame set up (using an old frame that I'll never alow to be used...). Pretend that the drop outs are brazed (or glued, this did start as a bamboo thread) to the chain stays, the CS have been fitted/mitered to the BB shell. The need now is to locate the CS and hold this position during their attachment to the shell. The good wheel being clamped to the bench top acts as a jig. The frame clamped in the vice so that all lines up. The wheel is centered with the main triangle, the CS are the right length, the seat stay length is known from the drafting and recreated on this set up. Of course thread or string is run from the head tube, past the seat tube and to the rear drop outs. Also a straight edge can be placed along the main frame tubes and extended past the rear rim to further establish the wheel's placement in reguard to the frame. I like to sight along the length of the frame and wheel using my eyes to see how the rim-frame lines up. When doing this all everything moves a bit, when one item it tweaked another changed so a long time of back and forth is done to get all in line.

    Once in line, the CS/BB shell junction is dealt with. In metal tubes this would be tacking. Perhaps pinning one CS/shell socket to fix some of the dimensions while setting all up and then pinning the other before rechecking and tacking. For bamboo you'll have to figure out this initial bonding step. Once the CS pair are both tacked to establish their angle with the main frame, drop out spread and length the full joining can be done. In metal I will recheck the wheel fit/position/frame alignment after brazing as heat does funny things to the hoped for. It's common to need to file the drop out a touch to correct slight errors. At this point this filing should be limited to the length of CS only.

    The frame is reclamped in the vice and the wheel is reset, Any SS length errors (or side to side/off center ones too) are corrected now by bending the CS to have the wheel sit even and again line up with the main frame. Once this is reestablished and locked in place the SS pair is mitered to fit (this is why it's nice to have two vices and benches...). I will allow one SS to have some drop out attachment adjustment. For classic tab style drop ous this is cutting the tab slot a touch longer. This means that the final SS length (or how the wheel sits vertically) can be played with as a last step.

    So once the SS are in line they are attached at their top first then one side at the drop out second. A final wheel centering/vertical check/correction is done and that second SS/drop out is brazed. After cooling recheck and file the axle slot to correct any small errors.

    The fork is done with the same wheel clamped to bench method. But here another tool is used. A sighting tube made of a small diameter tube is wrapped with tape in a couple of places along the length. the tape is built uo so that the tube can slide into the steerer and snug up. I like to have one wrap of the tape enter the butted section a touch and the other rest in the upper end of the steerer. Now you have a way of looking along the steerer's axis with more focus. With the wheel clamped onto the bench and the steerer/crown in the vice you can aligh the sighting tube with the wheel by looking through the valve hole to the rim's far side. What you have created is in essence a long straight edge through the center of the steerer, and across the wheel'd diameter. When the sighting tube (steerer) and the rim are all in line the fork is centered and in line. It's straight forward to miter the blades to have this be the case after setting it all up. Next is the fork's twist. This is simple to estiblish with a couple of straight edges (notice the Campy one in the photo? It has been additionally surface ground and a center notch made in it) placed across the blades neat the crown and at the drop outs (or the axle is used as theat edge).

    Once all is straight, aligned and the rake is what you want the blades/crown can be brazed/glued. After joining alighment will be done and some drop out filing is likely for the first few frames (and some times many others) .

    As I have tried to explane the tools needed to build a straight (enough) frame are common or not hard to make. A good understanding of frame alignment, common tool sense and patience will go a long way towards getting a very rideable frame. Again how some of the joining or aligning steps will be done with bamboo, with it's differences compaired to metal tubes, is your problem. But the aligment issues are not hard or require fancy and expensive tools.

    I've attached photos showing some of the set ups. Feel free to ask for more details. Andy.

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