Filed In: Process
Father/Daughter Project - Part 14
Wednesday, January 29, 2020 | Chris Blandford
Finishing the fork:
3. Rake blades
4. Tab dropouts; slot fork blades
5. Braze dropouts to blades
6. Finish blade ends
7. Braze blades to crown
9. Finish crown
10. Machine race seat
Time to get the fork blades ready. For this bike, I decided to use a pair of oval chainstays as fork blades. The oval of the chainstays wasn’t the same as the crown’s sockets, however, so I had to nudge the oval-ends of the chainstays in my vise. I also used pliers and a small tack hammer to umm… smith?... the crown a bit. It was a tad loose in spots; a few taps and nudges here and there got everything fitting nicely. Again, going for that snug slip fit, just like the steerer/crown.
Once raked, I compare to my drawing and trim both ends of each blade. As with the chainstays, there’s a bit of a balancing act here to make sure the blades, the curve of the rake, and the dropouts end up as intended.
Next I put a tab on the dropouts, as described previously when I made the chainstay sub-assemblies. Once tabbed, I load the dropouts into the jig, slide the blades into place, hold the tops of the blades with the crown/steerer assembly, and use a straightedge to scribe a “front” line onto the blades. Then I measure the dropout/blade angle, and slot the blade. If everything goes well, I have a tight fitting slot/dropout and also no twist in the blade that would mess with the crown fit up. All good this time around.
Next I dress the ends of the blades, clean everything up with 80-grit and isopropyl, (bronze) braze the dropouts to the blades, soak, and finish off the ends.
Once the blade/dropout sub-assemblies are complete, I check their length. I do this as shown, first using a crown (I had an extra of the same model lying around) with a steerer inserted and comparing its center to a wheel’s rim. I also use my workbench’s “corner” and some blocks to compare against one another. I adjust the blade length (if needed) and square up the ends on my belt sander.
Finally, I drill vent holes in the tops and bottoms of the blades, clean everything with 80-grit (especially the insides of the crown sockets) and isopropyl, then flux and (silver) braze the blades into the crown sockets. This is done in the jig. As with the steerer, I fill these things up, to the detriment of my “shorelines”. Someday.
Cool and soak.
To finish the fork, I use files to remove the casting marks and the little brazing-helper nubs on the crown. Then I machine the crown race seat with my Park tool cutter.
And that’s that. For what it’s worth (nothing), I love making forks (and stems, for that matter). They’re relatively easy to make and really fun to braze and finish. It’s a bummer that so few pro builders can justify the end result--or the time spent--to their customers. If all I was building for these bikes were the “frames”, I’d feel like I was doing way less than I could (or should). In fact, I’d love to eventually learn how to make other parts… cranks, brakes, seat posts, bars, etc. Why not?
Speaking of, time to figure out the brakes! Back soon.