Filed In: Process

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.

Filed In: Process

Father/Daughter Project - Part 12

January 21, 2020   |   Chris Blandford

For today:

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

Filed In: Process

Father/Daughter Project - Part 11

January 17, 2020   |   Chris Blandford

All right, moving on. For today:

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16. "Bridges"
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I've only ever made bridges out of round tubing, but I thought I’d try something different on this little bike. I like the look of the plate reinforcements I’ve seen on a few different mixte-style bikes. So, I decided to ditch regular, round bridges all together and purchased some 4130 sheet steel from Aircraft Spruce.

I started with poster board (actually, this was a manilla folder that was within arm’s reach). I traced and trimmed until I had the pieces and shapes that I was satisfied with. Then I transferred the shapes on to the steel and cut them out with a cutting wheel, cleaning them up with files and checking that they fit well.