(59 days until the 2012 WHPSC)
Back to the drawing board to design a fork fixture.
Time to make another mess at the mill.
Fly cutting the top of the fork welding fixture.
Milling the fork welding fixture.
More milling
More fly cutting
Foam Brick and Fork Stanchions
(61 days until the 2012 WHPSC)
Foam halves glued to steel armature
About as aerodynamic as a Winnebago right now
Boring a chunk of aluminum to hold the fork stanchions for machining
The finished stanchion holder
First half of first fork stanchion
Checking the fit after machining the second half of the first fork stanchion
Closeup at the fork crown end
Closeup at the dropout end
Another closeup showing the notch resting on the fork crown
Here's what the finished stanchion looks like with the holder removed
Like the world's largest hypodermic needle
Checking the fit of the second stanchion
Closeup of the fork crown end
Closeup of the dropout end
Another closeup showing the notch resting against the fork crown. Time for a welding fixture!
Fork Welding, Dropouts, Stanchions, and Body Tooling
(62 days until the 2012 WHPSC)
Fixturing the crown and steerer tube for welding
Right after welding the first pass across the top of the crown (still raging hot)
As you can see, there's not much room
Time to design a fork stanchion...
... and a dropout
Another view of the aluminum mockup for the dropout
Machining the dropout on the drive side (this is the real chromoly dropout, not the aluminum mockup)
Kind of on a whim, I decided to machine a slot in the dropout. Our endmill selection is somewhat limited, and our only Ø3/4" endmill is a 2-flute. Plunging a 2-flute endmill through chromoly seemed sketchy. I chickened out, and used a fresh 1/2-inch 4-flute to mill a pocket, then switched to the 3/4-inch mill to finish the ends.
I like it!
Dropout with stanchion mockup
Meanwhile, time to start the body! Dad marking the foam for routing to accommodate the steel armature...
Closeup of one of the routed grooves. Even tough I followed my dad with the vacuum, foam went everywhere!
Steel armature laying in the routed grooves
Closeup, showing the armature resting in the routed grooves
Dad drizzling honey on the foam - this thing is going to be sweet!!!
Actually, that's Gorilla Glue. Friendly advice: wear gloves when working with Gorilla Glue - it takes a couple of days to wear off!
Crowning achievement
(63 days until the 2012 WHPSC)
Buck it!!!
This is one of the steps I was dreading. I need to bend 1/4 inch thick chromoly plate into a "U" to form a fork crown.
I welded a piece of thick walled tubing to a 1.5 inch thick piece of steel plate. The buck is robust, but I anticipated the chromoly plate would put up a good fight. Armed with an oxy acetylene 'rosebud" and a five pound sledge hammer, I heated and smacked the metal around.
Voilà!
Here's what the crown will look like on the wheel
Triple-checking where everything is going to fit
Machining the fork crown to accept the steerer tube
Introducing the crown to the steerer tube
Another view of the crown and steerer tube