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Posts Tagged CNC

Tour Easy Daytime Running Light: Now with Chirality!

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:

Fairing Flashlight Mount - Right side - solid model

Fairing Flashlight Mount – Right side – solid model

And for the left side:

Fairing Flashlight Mount - Left side - solid model

Fairing Flashlight Mount – Left side – solid model

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:

Fairing Flashlight Mount - Mary approaching

Fairing Flashlight Mount – Mary approaching

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:

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Tour Easy Daytime Running Light: Pile of Prototypes

Although I wish I could come up with a finished design in one pass, usually I end up with a big pile of nope before producing the one I want:

Fairing Flashlight Mount - Iterations

Fairing Flashlight Mount – Iterations

The mounts on the left show the progression from large hemisphere balls to the same-size finger ball to the smaller finger ball, with the smaller cyan arch clamp in the foreground still festooned with its support structure. The stack of plates to the right (with the original faded & distintegrating ABS plates in the bag) comes from reprinting in cyan to match the small mounts now on the bikes:

Fairing Flashlight Mount - rounded

Fairing Flashlight Mount – rounded

Hey, it’s time for a ride!

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Tour Easy Daytime Running Light: Improved Ball Mount

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

Flashlight Ball Mount - flattening fins

Flashlight Ball Mount – flattening fins

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:

Fairing Flashlight Mount - Finger Ball - solid model

Fairing Flashlight Mount – Finger Ball – solid model

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.

Fairing Flashlight Mount - Finger Ball - solid model - support fins

Fairing Flashlight Mount – Finger Ball – solid model – support fins

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:

Flashlight Mount - finger ball

Flashlight Mount – finger ball

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:

Flashlight Mount - LC40 - finger ball - side

Flashlight Mount – LC40 – finger ball – side

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:

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Torchiere Lamp Shade

A pair of torchiere lamps lit the living room for many, many years:

Torchiere Lamp Shade - original

Torchiere Lamp Shade – original

During their tenure, they’ve gone from 100 W incandescent bulbs to 100 W equivalent” CFL curlicues to 100 W equivalent” warm-white LED bulbs. The LEDs aren’t up to the brightness of the original incandescents, but you can get used to anything if you do it long enough.

After so many years,  the plastic shades / diffusers became brittle:

Torchiere Lamp Shade - original broken

Torchiere Lamp Shade – original broken

That’s after a bump, not a fall to the floor. So it goes.

Some casual searching didn’t turn up any likely replacements. The shade measures 14 inch = 355 mm across the top, far too large for the M2’s platform, but maybe a smaller shade in natural PETG would work just as well.

ACHTUNG! This is obviously inappropriate for the original incandescent bulbs and would be, IMO, marginal with CFL tubes. Works fine with LEDs. Your mileage may vary.

OpenSCAD to the rescue:

Torchiere Lamp Shade - section

Torchiere Lamp Shade – section

That’s a section down the middle. The top is 180 mm across, leaving 20 mm of general caution on the 200 mm width of the platform. The section above the sharply angled base is 90 mm tall to match the actual LED height, thereby putting them out of my line-of-sight even when standing across the room.

I ran off a short version, corrected the angles and sizes for a better fit, tweaked the thickness to fuse three parallel threads into a semitransparent shell, and …

Torchiere Lamp Shade - M2 platform

Torchiere Lamp Shade – M2 platform

Producing what looks like thin flowerpot required just shy of seven hours of print time, as it’s almost entirely perimeter, goin’ down slow for best appearance. The weird gold tone comes from the interaction of camera flash with warm-white CFL can lights over the desk.

If you hadn’t met the original, you’d say the new shade grew there:

Torchiere Lamp Shade - no epoxy

Torchiere Lamp Shade – no epoxy

It’s definitely a Brutalist design, not even attempting to hide its 3D printed origin and glorying in those simple geometric facets.

Those three threads of natural PETG makes a reasonably transparent plate, clear enough that the bulb produced an eye-watering glare through the shade:

Torchiere Lamp Shade - no epoxy - lit

Torchiere Lamp Shade – no epoxy – lit

So I returned it to the Basement Laboratory, chucked it up in the lathe (where it barely clears the bed), dialed the slowest spindle speed (150 rpm according to the laser tach, faster than I’d prefer), and slathered a thin layer of white-tinted XTC-3D around the inside:

Torchiere Lamp Shade - lathe spinning

Torchiere Lamp Shade – lathe spinning

For lack of anything smarter, I mixed 2+ drops of Opaque White with 3.1 g of Part A (resin), added 1.3 g of Part B (Hardener), mixed vigorously, drooled the blob along the middle of the rotating shade, spread it across the width using the mixing stick, smoothed it into a thin layer with a scrap of waxed paper, and ignored it for a few hours.

If the lathe perspective looks a bit weird, it’s perfectly natural: I raised the tailstock end enough to make the lower side of the shade just about horizontal. Given the gooey nature of XTC-3D, it wasn’t going anywhere, but I didn’t want a slingout across the lathe bed.

The lit-up result isn’t photographically different from the previous picture, but in person the epoxy layer produces a much nicer diffused light and no glare.

I might be forced to preemptively replace the other shade, just for symmetry, but we’ll let this one age for a while before jumping to conclusions.

The OpenSCAD source code as a GitHub Gist:

 

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Tour Easy Daytime Running Light

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

Tour Easy Fairing Flashlight Mount - front overview

Tour Easy Fairing Flashlight Mount – front overview

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:

Tour Easy Fairing Flashlight Mount - front detail

Tour Easy Fairing Flashlight Mount – front detail

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:

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Tour Easy Daytime Running Light: Fairing Mount

The fairing mount must aim the flashlight generally parallel to the ground and slightly toed-in toward the bike’s frame, ideally holding the ball more-or-less in the center of its adjustment range. I eyeballed a protractor for the initial estimates and got it reasonably close on the third try:

Tour Easy - J5 Tactical V2 - front

Tour Easy – J5 Tactical V2 – front

One more skilled in math than I could define a matrix transformation between the solid model’s XYZ coordinate space and the fairing’s XYZ space, then figure the reverse transformation allowing you to convert real-world angles back to the model’s space. I winged it by setting up adjustments to rotate the ball clamp ring on all three axes around its center:

Lifting the ring upward by half its OD leaves it tangent to the XY plane, firmly embedded in the blank fairing clamp plate, and, through the magic of 3D printing, looking like it grew there.

In practice, aligning the ring isn’t too difficult. Align an eyeball along each of the mount’s axes, center a protractor on the ball with it perpendicular to the line of sight, rotate it so the baseline is level / straight-ahead / crosswise, read off the angle, then type it in. Of course you’ll get the sign wrong at least once.

For a given set of those angles, the mount looks like this:

Fairing Flashlight Mount - Mount - rear view - no support - solid model

Fairing Flashlight Mount – Mount – rear view – no support – solid model

You can determine by inspection there’s no way to orient the shape for E-Z building, although putting the plate flat on the platform has a lot to recommend it.

The outside being a spherical section, the overhangs will curl upward, so (as with the ball around the flashlight) rows of fins anchor the perimeter threads:

Fairing Flashlight Mount - Mount - rear view - solid model

Fairing Flashlight Mount – Mount – rear view – solid model

The fins are just under two threads wide to eliminate any possible infill, with a simple sphere chopping their tops to fit just inside the clamp:

Slic3r built support structures under the overhanging screw bosses:

Fairing Flashlight Mount - Mount - rear view - Slic3r

Fairing Flashlight Mount – Mount – rear view – Slic3r

It also added weird little towers that don’t come close to touching the clamp’s lower surfaces, which is why I added those fins. The automatic support should extend to one thread thickness from the bottom surface, but that’s a hard calculation to make for a spherical section represented by tesselating triangles.

After a few test rides, the whole affair seems to be both holding together and holding the flashlight, so it’s good enough for now. A twilight ride around the block may be needed for better aiming, though.

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Tour Easy Daytime Running Light: Ball Clamp Ring

With the flashlight firmly clamped inside its ball, a surrounding clamp ring holds the ball on the mount:

Tour Easy - J5 Tactical V2 - front

Tour Easy – J5 Tactical V2 – front

The solid model chops a sphere to a completely empirical 70% of the inner ball’s length (which, itself, may be truncated to fit the flashlight grip) and glues on a hull containing the M3x50 mm screws:

The complete ring looks about like you’d expect, although it’s never built like this:

Fairing Flashlight Mount - Clamp - show view - solid model

Fairing Flashlight Mount – Clamp – show view – solid model

The top half builds as an arch on the platform:

Fairing Flashlight Mount - Clamp - build view - solid model

Fairing Flashlight Mount – Clamp – build view – solid model

The uppermost layers on the inside of the arch have terrible overhang pulled upward by the cooling plastic, so the builtin support structure hold the layers downward. The preview shows they don’t quite touch, but in actual practice the support bonds to the arch and requires a bit of effort to crack off:

Fairing Flashlight Mount - support structures

Fairing Flashlight Mount – support structures

The ones on the right come from my (failed) attempts to build the ball hemispheres in the obvious orientation. It’s worth noting that my built-in “support” both bonds to the part and breaks off in one piece, quite unlike the pitched battle required to separate Slic3r’s automatic support structures; I think that’s the difference between the minimum feasible and maximum possible support.

Anyhow, the inside of the arch requires only a bit of cleanup with a ball mill before it clamps firmly around the flashlight ball. In the normal orientation, the space over the missing ball cap snuggles into the cleaned-up part of the arch and there’s enough friction on the remaining ball to hold it in place. If it does joggle loose, a wrap of tape should provide enough griptivity.

I started by assuming socket-head cap screws and brass inserts embedded in the clamp ring could provide enough force to hold everything together:

Fairing Flashlight Mount - Clamp - screw inserts - solid model

Fairing Flashlight Mount – Clamp – screw inserts – solid model

The head recesses into the top opening and the insert sits just below the split line on the XY plane. That turned out to be asking a lot from a pair of 3 mm knurled brass inserts, even with JB Weld in full effect, and I wasn’t at all confident they wouldn’t pop out under duress and fling the flashlight away.

Each screw now compresses the entire boss between a pair of washers and the nyloc nut won’t vibrate loose. The screws also serve to stiffen the clamp ring front-to-back, although I’m not convinced it needs any reinforcement.

I also considered splitting the ring parallel to the front, right down the middle, with screws extending through both halves:

Fairing Flashlight Mount - Clamp - Front Back split - solid model

Fairing Flashlight Mount – Clamp – Front Back split – solid model

It’d be trivially easy to build the front half face-down on the platform, but the rear would have only half the surface area bonded to the plate against the fairing, which seemed like a Bad Idea. Worse, I couldn’t figure out how to align the rear half on the plate with enough room for the nuts / inserts / whatever and alignment space around the front half.

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