SMART JEWELRY BOX

The project includes laser cutting, 3D printing, programming and electronics. I designed and implemented it as a part of a school project. Its outer shell is made with a laser machine, a sorting box for the jewelry is made with a 3D printer, and an electronics section of the work is placed under the false base. In addition, there is a programming section where Micro:bit is programmed with LED lights to select jewelry randomly. Watch the video!

• 3D printer (Ultimaker 2+)
  • White PLA filament
• Laser machine
  
  • Laser plywood 2mm, 4mm
• Sandpaper
  • p240
• Glue
  • Eri Keeper
  • Hot glue
• Surface treatment/finish
  • Cold pressed linseed oil
  • Osmo Color wood wax, red
• Electronics
  • Micro:bit v2
  • Sparkfun micro:bit breakout board
  • 6 LEDs (5 mm, super bright & warm white, 60 degrees light ankle)
  • Sparkfun micro:bit battery holder
    • Two AA-batteries
  • Push button (ON-OFF)
  • 8 Female to female jumper wire (also male to female works)
  • Connecting wire (90 cm)
  • (Drilling machine)
  • Adjustable wrench
  • Caliper
  • Ruler/measuring tape
  • Electric wire stripper/cutter
  • Soldering iron
    • Pewter solder wire

The outer shell of the jewelry box is made with a laser machine. I found a ready-made model on the internet that I modified a bit (the box is downloaded from https://3axis.co/laser-cut-book-box-with-living-hinge-cdr-file/6o3y6zq7/). I changed the image on the cover to another and also wrote a name on it (the flower imagine is downloaded from http://clipart-library.com/clip-art/spring-flowers-silhouette-24.htm).

Download the files and import into Inkscape, first the box. I deleted the original image from the box and then I brought this new flower image into the same file. This image was in pixel format so it needed to be converted to vector format. First select an image as active, then select "path". After that, select "trace the bitmap" and then "implement". Now you have two images. Drag them separately and delete the original image. Now you can resize the image and place it as you wish. Remember, that if you want to cut the image, place it far enough away from the edge. This will make the edge strong enough and you can glue another plywood under the image if you wish. After making all the changes, download the file in SVG-format and then open the file in Lightburn. There check the settings and edit to suit the material (4 mm laser plywood). Then transfer the file to the laser machine (you can see these settings for 4 mm plywood in the image above, change the settings a little bit for 2 mm plywood).

In addition to this, cut 4 other pieces: two pieces for the false bottom (3,3 cm x 13,4cm, 4 mm laser plywood), one piece for silhouettes background (12,3 cm x 17,8 cm, 2 mm laser plywood) and one piece for LED placement (13 cm x 17 cm, 2 mm laser plywood).

You can use the laser machine to make holes for the LEDs and pushbutton, if you want. I made the holes later and I used drilling machine for that. In both ways, measure the diameter of the LEDs and the push button with a caliper to get the right size holes.

The sorting box is made with a 3D printer. You can access the finished file by downloading it from below and opening it in Ultimaker Cura. There check the printing settings, such as printer and material (some settings can be changed, e.g. layer height 0,3 & infill 15% to speed up printing). When the settings are OK, press "slice" and Cura will tell you the estimated print time and the estimated amount of material. If you are using a USB- or SD-card, attach it to your computer and then press "save to disk". Insert the memory card into the 3D printer and select "print" from the main menu. Then select the correct template from the files on the memory card. Printing took about 3 h and 15 min with my settings.

You can also go to Tinkercad to make your own sorting box. To get started, select from the right edge two boxes, one solid and the other hole and drag them to base. Select the hole box as active and lift it desired amount from the cone above it. Lifting the box will affect the thickness of the bottom. Then select both boxes as active, press "align", center the boxes and last, press "group" to connect the boxes. You can make similar boxes by selecting item active and pressing CTRL+C and CTRL+V and then dragging it to wanted place. You can make boxes of different sizes by resizing them by selecting the piece as active. At the end, remember to check that you have "grouped" everything. At this point, you can also change the outside dimensions to match the inside dimensions of the laser box. When you are ready, download the file to the computer in STL-format and then transfer to Ultimaker Cura.

I did a few experiments on the thickness of the base and how the light comes through it. I tried this with 2 mm, 3 mm and 4 mm pieces and I think the last two worked best here. However, due to resources, I had to implement the box with a 1.5 mm bottom. This also seemed to work just fine.

Lightly grinding laser-cut parts with an eccentric grinder (sandpaper p240). Then surface treat the piece that comes behind the lid pattern if you want it to come in a different color than the rest of the box. Before surface treatment, measure and draw the marks where the piece will be glued (for example, lines to the corners). Then put marks on the area where the paint will be + a little extra. Make sure the paint comes under the entire pattern. The edges of the plywood are not painted, so insert masking tape into them as if it were a frame. Surface treat this part and remove the masking tape after painting.

The pieces of the box are glued in two parts. First glue the pieces of the original box. Attach the clamps lightly around the box. After that, glue also pieces for the false base and the piece that comes behind the lid pattern (make sure that the surface is dry). When gluing the latter piece, make sure that the glue only comes in places where there was masking tape. Fasten well with clamps. When using clamps, be sure to place some waste pieces of wood between the clamp and your work so that they do not leave marks.

I used Eri Keeper for gluing and cold pressed linseed oil and Osmo Color wood wax (red) for surface treatment. You can also use others that are suitable for the material.

The programming is shown in the pictures and can also be found in the attachment. Its idea is that when you can’t decide which jewelry you want to wear, the jewelry box will make the choice for you. At the beginning of the code, after pressing the button, the LEDs flash five times in a row. Then the Micro:bit randomly draws one LED that stays lit for a moment. You are also free to customize the code to your own (https://makecode.microbit.org).

Connect the Micro:bit with USB cable to the computer when the code is complete. Then download the code to the computer. Once the file is downloaded, it should be transferred to the Micro:bit: locate the file on your computer (usually downloaded files-folder). Then just drag the file to the Micro:bit folder.

Above is a picture of the wiring diagram (the push button I used had two feet). The Micro:bit is connected to the breakout board and battery holder. When using female to female jumping wires, cut off the other end of the wire and strip it. If you use male to female jumping wires, cut off the end of the male. Do the same for all eight wires. Then cut the connecting wire into six equal parts (about 15 cm) and strip off the ends.

Make the wiring as shown in the picture above. The jumping wires are placed in the following places: GND, P0, P1, P2, P5 (push button), P8, P12 and P16. Connect the other end, which has been stripped, to the longer leg of the LED (anode). Then connect the wires to the push button: connect the wire from P5 to one leg and the wire from GND to the other leg. Then connect the connecting wire to the same leg to which GND was connected. Then connect the other end of the wire to the shorter leg of the LED (cathode). Then just add the connecting wires between each LED, from cathode to cathode. Finally solder the joints. Be extra careful when soldering the wires to the push button, so that they do not touch each other. You can also slightly bend the LED legs and breakout board pins to accommodate the electronics portion in a smaller space.

Last, drill a few holes if you didn't make them earlier with a laser machine. Measure and draw the locations for the LED lights and the push button. Then measure with a caliper their diameter, and select the drill bit accordingly. Then put the LEDs in place and secure with hot glue on the back. Lastly, put the push button into place and secure with a wrench.

The duration of the project can vary very much. It is influenced by, among other things, the number of students, resources, previous experience and possible changes to the project. I estimate that the project will take about 10 hours at school. Laser work takes about 2 hours, 3D printing takes about 4 hours, grinding/gluing/surface treatment takes about 2 hours and programming + electronics take about 2 hours. Some work steps can be speeded up if necessary, for example by multitasking during 3D printing.

The student's own design can be implemented in many different ways. The easiest way is probably to use the original laser cut box, and customize it to look like your own, using images, for example. Just remember to change it from pixel format to vector format if needed. In the programming section, the code can be modified to work slightly differently. In addition, a completely new sorting box can be made in the 3D section. The box is easy to make in Tinkercad. In this way, teaching is also easy to differentiate. Those who are progressing more slowly can proceed directly as instructed and those who are progressing fast can make some of the changes mentioned above, for example.

The required materials and supplies are listed up in the supplies section. It does not require greater material preparation as long as everything is in the required quantity. The amount of laser plywood is a bit tricky to calculate, but I would estimate that it would require roughly about 13 cm x 35.5 cm/2 mm laser plywood and 32 cm x 42 cm/4 mm laser plywood per student. This, of course, is only calculated if a large area of square plywood is used for the work. It is a good idea to arrange the pieces according to the material so that there is as little loss as possible.