process
- fabrication 1
fabrication pages:
p2 p3
Follow the steps of the fabrication process on these pages.
First is the design done on the computer which allows us to view all the various dimensions and how they work together. The program provides exact measurements for setting up the fixture and mitering the tubes.
Here, I've got the numbers on the clipboard and am setting up the frame fixture for this build.
A head tube is parted off on the lathe, then the ends squared and chamfered.
Rough cuts are done with a hacksaw to size the tubes for mitering on the machine.
After machine mitering they come out with rough edges that need to be taken down with a file, or the scotchbrite wheel.
After the tubes for the front triangle have been mitered and deburred I fit them up in the frame fixture and mark where I want the water bottles to be located. The tubes come back out of the fixture and holes are drilled for water bottle bosses using the milling machine.
After
drilling tubes,bottle bosses, and cable stops are cleaned and fluxed for
silver brazing.
In the background are the down tube and seat tube with bottle bosses,
and in the foreground is the top tube with two brake cable stops held
in place in line with each other by a cool tool made by Sputnik tools.
Hot Hot Jabanero!
Actually, not that hot - this is considered "low temperature" silver brazing, as the addition of silver makes the filler rod that will be added as soon as we get up to temp, melt at a lower temperature than brass. This is a good thing for the thin section of the tube, but still hot enough that I burn myself grabbing stuff before remembering it was just under the flame a minute ago....
What you didn't see (since I don't have that many hands I couldn't take the picture) is the addition of the filler rod. Here the silver-brazing has been done and there is a icy looking crust of flux on the joints which has protected it from contamination. A soak in hot water removes the flux.
I like to get the braze-ons done before joining the front triangle, so that any heat distortion does not affect the alignment of the frame.
Next the seat tube is welded to the BB. First the miter is checked and adjusted if needed, then tack welded in the fixture, then alignment checked, then welded, then checked again.
