New Metal Jig

New: pictures of the component pieces for my frame jig, which I am almost done with. All parts except for the axle came from scrap metal just hanging around in piles at maintenance shops up at school. All the machining was done with your typical Bridgeport, lathe, drill press, hand taps, etc . . . Thanks to Pepe Lajeunesse and Ehrling Heistad, who have been teaching me the finer points of machining.












Here is a shot of the completed metal jig. My grandfather, Pepe Lajeunesse, is on the left, and I am on the right. Pepe has spent a lot of time teaching me how to be a machinist.











 

Here is another shot of the jig.  Note how the machined steel cones slide along the steel rods, which are held a fixed distance from the metal plate.  The cones help to center the tubes, and also allow for any sized tube to be held. 

 

Here is the partial seat tube stantion, viewed from the top. There is a threaded hole in the base which will join the piece to the main jig backplate by a single bolt. The bolt will slide in a track (cut in the plate) so that many seat angles can be used.


















Here is the partial seat tube stantion, viewed from the front. A 3/4 inch steel rod wil pass through this hole, and then slide into the seat tube. A cone will slide along the rod and clamp the seat tube in place. Hopefully, using a cone will allow many seat tube inner diameters to be used.


















Here are the cones as mentioned above. Also, here is the bottom bracket pin.



















Here is a top view of the chainstay attachment. The dummy rear axle is cut for 120 mm (track spacing). All other sacing can be made by adding the appropriate spacers (here, two 5mm spacers are included for another road frame).





















Front view of jig. The fork is held upside-down so that the brass filler rod can flow with gravity into the crown joint (but not with this fork, I yanked it off my old Trek just to have something to put in the jig).


























Side view of the jig. In all likelihood, any new forks I build won't be raked before I braze them together.





















Closeup view of the steerer tube clamping mechanism. I cut a v-notch in the aluminum block and bolted it to the plate. The u-shaped clamp (comes commercially available as one piece) hooks onto a pin (press-fitted into the block) and holds the steerer in place.





















Closeup of the dropout clamping mechanism. There are two grooves cut in the plate: a narrow one in the bottom for the bolt that clamps the main piece, then a wider slot in the top for the actual base of the main piece. The main piece is slotted to fit in the groove. The front axle was made from round steel stock turned down to 100mm width, and the ends were threaded to fit hand-turned knobs which hold the front dropouts in place.

Thanks to David Bohm, Josh Putnam, Damon Rinard, Fred Parr,  and others whose ideas and information have gone into this page.


If you would like to get in touch with me, please e-mail me at: root@student.uchc.edu

Created September 20, 1998. Last updated February 8, 2003

visitors since October 2000



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