Tag: M2

In the unlikely event our bikes need two running lights or, perhaps, a running light and a headlight, the solid model now builds mounts for the right side of the fairing, as before:

And for the left side:

Ahhh, chirality: love that word.

Those pix come from a cleaned-up version of the OpenSCAD code that finally gets the 3-axis rotations right, after a rip-and-replace rewrite to deliver the ball model with its origin in the center of the ball where it belonged and rotate the ring about its geometric center. Then the rotations become trivially easy and a slight hack job spits out a completely assembled model:

if (Component == "Complete") {
  translate([-BracketHoleOC,0,0])
    PlateBlank();
  mirror(TiltMirror) {
    translate([0,0,ClampOD/2]) {
      rotate([-Roll,ToeIn,Tilt])
        SlotBall();
      rotate([-Roll,ToeIn,Tilt])
        BallClamp();
    }
  }
}

However, putting the center of rotation directly over the center of the base plate means the ToeIn rotation shifts the bottom of the clamp ring along the X axis, where it can obstruct the mounting holes. Shifting the ring by a little bit:

ClampOD*sin(ToeIn/2)

… keeps the ring more-or-less centered on the top of the plate. That’s not quite the correct geometry, but it’s close enough for the small angles needed here.

Aiming the beam slightly higher makes a 400 lumen flashlight about as bright as any single LED in new car running lights:

You can just barely make out the snazzy new blue plate on the left side of the fairing.

A bike’s natural back-and-forth handlebar motion sweeps the beam across the lane, so I think there’s no real benefit from blinking.

The OpenSCAD source code as a GitHub Gist:

The original ball around the flashlight consisted of two identical parts joined with 2 mm screws and brass inserts:

Providing enough space for the inserts made the ball bigger than it really ought be, so I designed a one-piece ball with “expansion joints” between the fingers:

Having Slic3r put a 3 mm brim around the bottom almost worked. Adding a little support flange, then building with a brim, kept each segment upright and the whole affair firmly anchored.

Those had to be part of the model, because I also wanted to anchor the perimeter threads to prevent upward warping. Worked great and cleanup was surprisingly easy: apply the flush cutter, introduce the ball to Mr Belt Sander, then rotate the ball around the flashlight wrapped with fine sandpaper to wear off the nubs.

The joints between the fingers provide enough flexibility to expand slightly around the flashlight body:

I made that one the same size as the original screw + insert balls to fit the original clamp, where it worked fine. The clamp ring applies enough pressure to the ball to secure the flashlight and prevent the ball from rotating unless you (well, I) apply more-than-incidental force.

Then I shrank the ball to the flashlight diameter + 10 mm (= 5 mm thick at the equator) and reduced the size of the clamp ring accordingly, which made the whole mount much more compact:

Here’s what the larger mount looks like in action:

The flashlights allegedly puts out 400 lumen in a fairly tight beam. The fairings produce a much larger and brighter glint in full sunlight than the flashlights, so I think they’re about the right brightness.

The OpenSCAD source code for the new ball as a GitHub Gist:

Pending more test rides, the flashlight fairing mount works well:

Despite all my fussing with three rotational angles, simply tilting the mount upward by 20° with respect to the fairing clamp aims the flashlight straight ahead, with the ball nearly centered in the clamp:

That obviously depends on the handlebar angle and the fairing length (which affects the strut rotation), but it’s close enough to make me think a simpler mount will suffice: clamp the flashlight into a cylinder with a slight offset angle, maybe 2°, then mount the cylinder into a much thinner ring clamp at the 20° tilt. Rotating the cylinder would give you some aim-ability, minus the bulk of a ball mount.

Or dispense with the separate cylinder, build the entire mount at the (now known) aim angle, clamp the flashlight directly into the mount, then affix mount to fairing strut. Rapid prototyping FTW!

For now, it’s great riding weather …

The OpenSCAD source code as a GitHub Gist: