Frame Alignment and Fixturing Table
Using a Bridgeport 9x36 milling table, bits of 80/20, and homemade parts to construct a bicycle frame tacking fixture and alignment jig.
The milling table was Brandon Ives idea and it seems like it'll be a good solution. I bought this one used for $40 (the freight cost 3x that). It's flat and the t-slots are very helpful for fixturing items in place.
Read MoreThe milling table was Brandon Ives idea and it seems like it'll be a good solution. I bought this one used for $40 (the freight cost 3x that). It's flat and the t-slots are very helpful for fixturing items in place.
Bottom bracket alignment post in action.
There is more to this than you'd think. The bottom is 2" in diameter and about 3.5" tall. It has 1/2"-13tpi threaded holes coaxially on both ends and 1/2"-13tpi threaded holes through the center of the other axis for handles. The bottom hole connects with a short piece of all-thread to a T-Nut in the table.
There is a bushing that you can't see that locates the bottom of the BB.
There is a brass bushing and washer that locates the top.
The top nut is made like the bottom, it is just about an inch tall.
![This is an alignment cone which can slide on 80/20. I like the idea of the seat tube cone that is in this 80/20 frame jig[1], but I didn't like that it couldn't be adjusted for height. My cone will mount to the block, which then mounts to a piece of vertical 80/20 extrusion.<br />
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I made this mounting block, but I decided to just buy 80/20 "manifold" blocks for the rest of them. They are $11 each which seems like a lot for $1.50 worth of aluminum, but it saves me about 45 minutes of work per block and I need 4 of them total (two for the head tube, one for the seat tube, one for the bottom bracket).<br />
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[1] <a href="http://www.instructables.com/id/SPHE0MXF1JZQZZZ/">http://www.instructables.com/id/SPHE0MXF1JZQZZZ/</a>](https://photos.smugmug.com/Bicycles/Fixtures/Frame-Alignment-and-Fixturing/i-BrqpLVB/0/f782b502/Ti/P1050151-Ti.jpg)
Guest
on August 13, 2008If you had the time, it would be great to see a photo showing the threading and such for this bottom bracket attachment.