Wednesday, July 3, 2013

Rapid Prototyping

Well, it ain't autocad, or even one of those newfangled 3D printers... this is what passes for rapid prototyping in my world.
Step 1:  the idea...  fit an even smaller/lighter rear caliper to the racebike, hopefully shedding more weight off either end of the bike.  Considering I rarely use the rear brake, it makes sense.  Purchase an AJP caliper, and stare intently at photo.

Step 2:  make template out of cardboard.  Line up caliper mounting holes and (as best you can) determine location of axle hole.

Step 3:  do the same thing with wood.  Now you begin to really pay attention to the shape of the piece, the exact location of mounting holes, and where the axle will go.  Wood allows some test fitting, including the spacer sleeve that will be press-fit and welded into place once everything is set.  The key thing here is that the hub of the stock wheel is a different diameter than that of the Carrozeria wheels, so I did have to remove the wheel from the bike to double-check everything.
Step 4:  start on the aluminum piece.  It's 6061 3/8" alloy plate.  This is the same temper as the sleeve that will work as a spacer for the rear axle.  Drill holes, chamfer, cut to shape.  Grind, file, sand, and grind some more.
Step 5:  it's still pretty rough, but the shape is getting there.  The hole on the upper right will be tapped for an M8 bolt.  I think there are some nice alloy Ducati tie rods (originally for suspension linkages) that at 270mm will be the right length.  I'll need to get the round bar stock bored to a 20mm slip fit for the axle, and then machined down to the right width, based on the stock caliper bracket.  I've drilled a pilot hole where the rod will be pressed in for an interference fit. This will allow me to line up the caliper on the rotor, with the right spacer width, and then get cycleboys to tig-weld it secure, along with welding an alloy bracket to the swingarm for the other end of the tie-rod.  A bit of a hassle, but I am determined to have the coolest rear caliper EVER on an ex650...

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