Filed In: Process

Father/Daughter Project - Part 14

January 29, 2020   |   Chris Blandford

Finishing the fork:


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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.

 

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Father/Daughter Project - Part 13

January 28, 2020   |   Chris Blandford

Moving on to the fork. Steps:

1. Fit and braze steerer to crown
2. Shape crown, if desired


I begin by fitting and brazing the steerer tube to the crown. The crowns I’ve worked with are nicely machined post-cast; to this point, they haven’t required much fiddling to fit nicely around the steerer. (I was taught that the steerer-crown interface should have no play, but should be loose enough to allow the crown to slide down the steerer under gravity.) In this case, I merely cleaned up the outside of the steerer and the inside of the crown with 80-grit emery. (I was also taught to orient the emery "scratch marks" in the direction one wants the silver to flow while brazing. So, I do that with everything I silver braze, as shown here.)

Once cleaned up, I drill a hole for a pin that will hold the crown to the steerer while brazing. I use regular hardware store nails for the pinning, tapering them slightly on my belt sander so that they fit tightly when I tap them into the assembly-to-be-brazed. Also worth noting is that I allow just a small lip of the steerer to protrude past the bottom of the crown. When I go to braze, I’ll do so “upside down”. Having a little lip there allows easier feeding of the silver filler.

Finally, I drill vent holes if appropriate. This crown is hollow in the shoulders. I vent fork blades top and bottom, so these holes will allow the blades to be vented directly through the steerer. Some crowns I’ve used don’t allow this; those forks’ blades just get a simple hole, somewhere up near the crown.

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Father/Daughter Project - Part 12

January 21, 2020   |   Chris Blandford

For today:


17. Make and braze on head tube reinforcement rings
18. Make and braze on seat tube collar/binder
19. Slot seat tube


I was planning on using a cast seat tube collar on this frame. When I went digging for the one I thought I had on hand, however, I discovered that it was the wrong size. So, I decided to make my own out of a Paragon binder and some .058” tubing (to slip fit the seat tube).

I began by mitering the binder to fit the tubing. Then I put a small slot on the opposing side of the binder. I need to figure out a better way to fixture these while brazing, but a slot and one of my usually-used-for-cable-stops Sputnik clamps works ok. Then I (bronze) brazed the binder to the tube.

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