Tuesday, September 04, 2007

you gotta start some where.........


david mc k.'s bike on the drafting board getting prepped up here....first step for every frame is putting a fresh sheet of paper on the drafting board and sharpening a #2 pencil and drawing a customer's body dimentions on the sheet. then, the bike is drawn into the customer's body. the bike is made to fit the person, not the other way around. and, the blueprint is used to extrapolate the miter-to-miter lengths and the angles which you will cut the tubes at. in the picture you are looking at, the tubes have been scrubbed shiny-clean with dishsoap and hot water inside and out. this does a few things: it de-greases the tubing, which is absolutely necesisary for proper metal joinery of any kind. second, it allows you to look for blemishes or dents resulting from munufacturing processes. third, with the tube all squeaky clean you can accurately measure the internal butting profiles to maximise the strength potential of your butting, the thicker sections at the end intended to maximise strength and dissipate heat. tubes come in an impressive variety of thicknesses, butting profiles, lengths and shapes to allow an experenced framebuilder to build the strongest, best-riding, most efficient frame he can. after this, you take them and roll them across the frame alignment table to locate any bows in the tubing. tubes always have a slight bow, which you orient in the up-and-down plane to build a straighter bike. the headtube piece with the two vent holes is cut from a 3' piece of raw material and faced to make both ends parrellel to each other, both the properly align the headset cups, and to insure that the headtube piece sits straight in the jig. the ventholes allow expanding gasses to escape during joinery, water to escape which is captured during expansion and contraction due to temerature fluctuations, allows for rust inhibitors to be sprayed in the frame, and minimizes heat distortion from brazing. the bottom bracket has also been vented. the fishmouthed piece is the seattube sleeve, it has also been cut from stock and coped on the vertical mill. it goes on the top of the tube and strengthens the seattube cluster, as well as eliminating distortion which would need to be reamed out to allow for proper seat post fit, weakening the frame. looks cool, too. and, no frame is built from one complete tubeset, but chosen from different manufacturers from around the world. here's this frames tubing list and it's maker and country of origin: headtube, toptube and down tube, truetemper, usa. seattube, tange prestige, japan. chainstays, dedacciai, italy. bottombracket shell and dropouts, paragon machine works, usa. the seattube sleeve and seatstays are made from seamless aircraft 4130 steel, usa. who thought there was so much before you ever start cutting tubes? more pics later, steve.

3 comments:

Anonymous said...

Great info, the more you can post about the technical reasoning behind material selection the better. I am hoping to order a bike from you by next summer, so keep up the "Frame building for idiots".

Craig said...

man I love shinny new tubes like that!
cheers,
big ring

Anonymous said...

Great explaination Steve. I always go away with more after reading your blog.

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