Bike Wheel Light

I'll be showing you my process for making a Bike Wheel Light.

I'll be using Cinema4D to model, but the specific tools I'm using ( sweep, extrude, booleans, etc. ) are available in most 3d programs.

I use these two measurements a lot.

.2mm - is what I use for clearance when I want a tight fit.

.75mm - with a .4mm nozzle, I get two printed paths side by side, with a slight overlap.

They'll be some printing info towards the end.

The distance from the center of the wheel to the light is the radius I used for the circle spline. The width is a standard reflector that came with the bike. I made place holders for the battery and contact plates. Zero out the battery axis so it will rotate along your circle.

Create a profile shape spline and sweep it along the circle with a Sweep Object. Using "Start" and "End Growth" trim the ends to make it the size you want, while also enabling Fillets to round off the ends. This will be the inside shell, so it just needs to be big enough so nothing pops out. The battery and the plates were the largest items, so I used them as my reference.

Note: The profile shape I used is shallower on one end, this goes on the inside of the arc. I had to do this is for it to print properly. The circular bevel going up together with the inside arc made the angle too shallow, and the print would fail.

Make the Body Editable and select all faces. Select Extrude and enable Create Caps, with an offset of .75mm. Use a Boolean Object and a Cube to cut the Body in half.

Starting with a half of the Body, select faces along the inside edge. I selected from the corner to about the center ( I didn't add any Tabs to the section where the LEDs are, as they would be visible. ). On the first Extrude, use an offset of .75mm, this is the tab thickness. I moved the bottom vertices up to give the bottom an angle, this is to remove overhangs for printing. I selected the top faces and used 2mm for the tab length.

I repeated the process and created a Tab at the center, between where the batteries will go.

Create Cubes for the battery cutouts, place them and the Body in a Boolean Object.

Battery Covers - Same as the last step, but this time make the Cubes .2mm smaller for clearance, and also set the Boolean Object to Intersect.

Battery Cover Tabs - Select faces on the inside of the Covers, but leave some on the top and bottom for the Offsets on the Body. On the first Extrude ( offset from Cover ), use an offset of .2 for clearance and .75 for tab thickness. On the second Extrude ( tab length ), I used 2mm for one end. On the other I used .5mm and rounded off the end, this will be the part that snaps in.

This is where those non extruded spots on the Battery Covers rest on.

Use a copy of the Battery Covers, and delete all but the the inverse ( to the Cover Tabs ) faces on the inside of the Covers. I moved these .2mm off the Cover for clearance using the Normal Move tool. From this point on it's similar to the tabs. Again using an extrusion of .2mm then .75mm ( .2 for the gap, .75 for the connection ), then used a Boolean Object with the Body set to Union.

Make a rectangular profile for the Internal Frame ( internal hight, and .75mm wide ) , then sweep it along a circle similar to the one used for the main shape. Create the battery tabs and use a Boolean Object set to Union to merge it all together. The parts that are poking out will be cut in the next step.

Starting with the Body, select all faces and use the Normal Move tool to expand the Body .2mm. Use this with the Internal Frame in a Boolean object. This will insure that the Frame fits nicely inside the Body.

The battery offsets are extruded splines profiled to fit the batteries. Cubes are used to cut out holes for the Plate Tabs.

To make the pins I used a Cylinder, and made it Editable. With the cap faces selected, I used Extrude Inner to make the "wall" of the pin, then Extrude down to make the hole.

For the pin the step are the same except Extrude Inner is .2mm smaller, then Extrude Up. The Cube is where the center mounting hole will be.

I started by cutting the center mounting hole using a Boolean Object. It goes through the Cube and the Body, I made sure to leave a .75mm border around the Cube. The clip locks are just cubes, which I pulled vertices down to make a triangle. The clip will be recessed, so I didn't place the locks flush at the bottom. The Glue Supports for the Frame are a triangle profile swept along a circle.

With a Spline shape for the Clip, I placed it in an Extrude Object, Made it Editable, and extruded the top section. I finally select the top outline vertices, and beveled them.

Parts list

• Small strip of flexible plastic (Used for switch)

• Copper tape (Attached to plastic strip)

• Small weight (I used a washer, gives weight to plastic strip)

• 5V LED strip

• AA battery contact plates ( It's what I have )

• 2 AAA batteries ( I used AAA because I can get them as rechargeable, and they're still affordable. )

Here are the STL files if you'd like to print one out yourself. You'll want to print them in the orientation provided for flexibility and strength. "clip" and "battery_covers" files will need support for printing.

Glue down the Contact Plates, make sure they're going in the same direction. Then stick on the led strip with the polarity facing the proper terminal ( I used the +- from opposite ends ).

The switch is really simple, it connects the two battery plates together. I used a plastic strip about 3mm wide with copper tape stuck to it. I soldered the copper side to one of the plates. I then glued a washer to the floating end for weight. The gap I needed was tiny for the switch to work properly.

Note: When you're finished putting the switch together you'll want to clean the contact area, the copper tape gets dirty quite easily. I used an emery board, be gentle.

With that you can finally put it together. Superglue the Internal Frame to one half of the Body, and dry fit the other for testing, the clip will hold it together. Make sure to glue the battery tabs as well, they're really flexible.

The Clip on the spoke works really well, I see why they used it on the reflectors. I feel the one I made could be more "clippy".

The LED strip I'm using is really low current, the 7 LEDs draw under 55 milliamps. With 800mAh from the AAA , you get about 14.5 hours of on time ( only when the bike is moving ).

The Battery Covers hold on tightly ( filing the short tab will fix it , or I could just fix the model ;) , and the batteries sitting pretty deep inside, they're difficult to get out.

The Battery Covers do show why printing orientation is important, they flex pretty far before coming out.

I think my next version will have some kind of charging port, so no battery covers, and use a small spring for the switch.