Making “The Petri Dish …”
Table of Contents
Making the installation
- Materials prep
- Electronics box
- The console
- Arduino + servo + linkages + breadboard
- OLED + magnifier
- Neopixels installation
- Finishing touches
General materials list:
- Servo motor, at least MG955 or equivalent
- 0.96″ OLED display, I2C interface (you can use a bigger one too)
- Two sets of 5v power supply adapter and 5v breadboard power module
- Assortment of jumper wires or 28AWG wires
- Thin gauge wire, ~10m
- Thick gauge wire, ~2m
- Tools; pliers, snips, wire strippers, power drill, 2 spanners
- Wood glue
- Scraps of plywood
- 2×1″ wood planks, single 10ft piece will suffice
- some clamps of various sizes
- M3 screws, M8 bolts
1. Making petals
- Create drawing plan for how many petals to be included in flower
- Get tools in order; snips, wire cutters, pliers, ruler
- Cut wires to length, about 60cm in our case. I am twisting a pair to create an interesting pattern as well as to make the wire thicker
- Use rounded pliers to twist
- Shape a petal using the drawing as a guide
- End off with a loop in the middle to allow for connecting a linkage later
- Flatten the tip of the petal
- Apply curvature to the shape
- A petal is done! Repeat till you are done (5 times in our case)
2. Attaching petals
- Use a thicker gauge wire to create a 6-sided polygon.
- Strip off a small section of the thin wire (~8cm)
- Coil on both ends to connect a petal to the polygon
- Repeat till all petals are connected! Make sure all petals can swivel back and forth freely
3. Petals’ Base
- Cut out a section of thicker gauge wire (~9.5cm)
- Twist on both ends, facing in different directions
- Connect one to each corner of the 6-sided polygon
- Twist an additional strand into one of a lollipop shape; this will act as the connector to the stationary plastic tube that supports the moving main metal linkage.
- Connect 2 linkages first, check if they are holding the petals equally. For my first try, it wasn’t(see picture with red circle). Adjust by making one of the linkages shorter.
- When fixed, continue with the rest of the linkages.
- With all the linkages connected to the stem base, you can twist the bottom of the wire around the plastic tube.
- Let’s begin making the final part of the flower!
4. Flower mechanics
- Twist another strand in the similar lollipop shape. This piece goes all the way through the plastic tube to the bottom. (~35cm, depending how long you make the stem..)
- Create a linkage that is slightly different. One of the ends is at a 45 degree to the other. You will need 6 of these as well.
- Connect one end to the loop in the middle of the petal. The other goes to the ‘lollipop’ wire made in step 1 of this section.
- Again, some of the linkages might be longer than others. Adjust accordingly till all six are connected equally to the middle .
- When you are done, you can test it out by pushing and pulling gently at the other end of the rod made in step 1. (See video below)
The Flower is done!
Making the Installation
1. Prepping the materials
Plywood(1.2cm or thicker)
- 4pc: 20x11cm (housing sides, A)
- 2pc: 15x15cm (housing lids, B)
- 1pc: 20x25cm (console surface, C)
2 x 1 inch planks(pictured darker colored here)
- 1pc: 20cm (center connector, right notch on both sides: 2.5cm depth, half width, D)
- 1pc: 30cm (middle connector, left-right notch, E)
- 1pc: 7cm (console surface connector, left notch, angled cut at other end, 60-degrees, F)
- Cut to dimensions the above.
- Use a compass to draw a circle to act as a guide to cut out rounded ends.
- Drill 8mm holes or whatever size bolts that you are using to link the connectors together.
2. Electronics box
- Attach the center connector(D) to one of the housing lids(B). You can use M3, 25mm screws.
- Drill a hole that is big enough for the plastic tube through the middle of the center connector(D) and the housing lid(B). An additional hole is drilled for some wires for electronics.
- Connect two pieces of housing sides(A) with a small hinge. You can use M3, 10mm screws. Do the same for the remaining two pieces(A).
- Place the two sets of the connected housings at right angles to each other to form a 4-sided box.
- Align the top housing lid to this housing and drill a screw through to connect them.
- Take note to only connect one of each of the two sets of housing sides(A), so that we are still able to open the box on two sides. (see picture for a view from the underside)
- Attach the bottom housing lid(B) as well, with screws.
- Short sticky foams are placed to limit how much the housing sides can be pushed in.
- A hole is drilled on the attached side of the housing for wires.
3. The console
- 2pc: 7 x 8cm (cuboid sides, G)
- 1pc: 5 x 8cm (cuboid side, H)
- 1pc: 13 x 8cm (cuboid base, I)
- 3pc: 5 x 8cm (jar sides, J)
- 1pc: 8 x 8cm (jar base, K)
- Cut to dimensions using the above specifications; these are for making slots for holding a cuboid and a small glass jar.
- Draw a 4x3cm rectangle and a circle of 4.6cm diameter on the console surface(C), then cut them out.
- Drill four equally spaced holes in the middle connector(E); these are for LEDs
- For the cuboid container, use 2 pieces of (G) and 1 piece of (H) as sides, and 1 piece of (I) as base, and glue them together, you can use wood glue like Titebond.
- For the glass jar, use 4 pieces of (J) and 1 piece of (K) and glue them up as well. See picture for reference.
- Glue console surface connector(F) to the top, middle part of console surface(C).
4. Arduino + servo + linkages + breadboard
- 5pc: 1.3 x 2.5 x1.6(thickness) cm (servo supports, L)
- 1pc: 7 x 4 x 0.5(thickness) cm (servo base plate, M)
- Cut to dimensions using the above specifications; these are for making a housing to hold the servo in place.
- Drill 2 holes or more on the base plate(M) for screwing it to the enclosure. Make sure that you can still access these after the servo is installed.
- Glue two sets of two pieces of (L) together to form (L2)
- Align the servo and glue up a piece of (L2) to the base plate on one end, to allow for the servo to be attached via m3 screws.
- Then glue a piece of (L) at an angle, and glue a piece of (L2) lying flat on top of it. See picture for reference. Make sure that you glue these two pieces in a way that allows you to remove the servo later. Then screw the servo onto this support with M3 screws as well.
- Install plate with servo onto enclosure. You can temporarily remove one of the screws from the top and bottom of one side of the enclosure, and swing open the side to have more access to the inside of the enclosure.
- Create a linkage as shown to connect it from the servo to the bottom of the metal linkage of the flower.
- Install Arduino onto one of the swinging side panels with M3, 10mm screws. Attach breadboards with double sided tape as desired on the inside. Here you can see I have attached a short one inside, and another extra breadboard on the other swinging side panel.
5. OLED + magnifier
- 2pc: 11.6 x 2cm (glue up these 2 pieces together, the OLED will be attached to this, N)
- 4pc: 5 x 3.2cm (side supports to hold m8 bolts, O)
Plywood strip(width: 1.1cm , height: 1cm)
- 4pc: 8.4cm (housing’s top and bottom frames, P)
- 1pc: 2cm (housing’s bottom spacer, Q)
- 2pc: 7.2cm (housing’s side spacers, R)
- Cut to dimensions using the above specifications; these are for making a magnifier to increase the viewing size of the tiny 0.96″ OLED we are using.
- Glue up the pieces using the supplied CAD pictures as reference.
- Drill a M8-sized hole on each side of panel (O)
- Align with the glued up panels (N) and drill m8-sized holes.
- Attach the magnifier housing and OLED pieces with M8 bolts and nuts as shown.
- Attach hinge(0.5 x 1.5inch) at back, bottom of housing.
- Then attach this assembly to the center connector as shown.
- The OLED display is held in place with blu-tack, and wires can be tucked from behind as shown.
6. Neopixels installation
- Solder wires onto Neopixel(SK6812)
- For center connector(E), feed wires through holes and attach them together in series. Remember to follow the indicated direction on the underside of each Neopixel.
- Place a Neopixel a little above the center area of the petal as shown.
- Feed a Neopixel through hole in console area.
- Add another breadboard power supply module for powering the center connector and console’s Neopixels.
- The flower petal’s Neopixel will be powered together with the servo motor.
7. Finishing touches
1.5cm wide single-sided sponge tape
- 2pc: 6.8cm (horizontal outer linings)
- 2pc: 10.5cm (vertical outer linings)
- 2pc: 3.2cm (horizontal inner linings)
- 2pc: 3.8cm (vertical inner linings)
- 1pc: 3.5cm (bottom lining for pipette)
- 2pc: 11.5cm (side linings for pipette)
- 2pc: 5cm (side linings for magnifier)
- 1pc: 8cm (left vertical line for manual area)
- 1pc: 14.5cm (horizontal line for manual area)
- 1pc: 6cm (right vertical line for manual area)
- 2pc: 20.7cm (side linings for central connector)
- 3pc: 6cm (for wrapping flower stem)
- 1pc: 16cm, cut to half of width (lining electrolyte area)
1pc: 10 x 60cm cloth
- Cut single-sided foam tape according to dimensions and stick them onto the console area.
- Use bubble wrap to insulate stem area. Then use aluminium foil to wrap it up. As we are going for an all-metal look for the flower, its a good choice.
- Then use wide masking tape to cover the neopixels as shown.
- We will next use bubble wrap to cover these areas, partly to act as a sort of diffuser for the LED lights. Do this for both the dripping area and the center connector as shown.
- The finished product with lights is shown above.
- Fix the black cloth around the console area, you can use your own methods. Here I used double-sided tape and some straps.
- Print the artwork(below) for an instruction manual and paste it at the manual area.
8. We are done !
- Use M8 bolts to connect the 3 connectors(D, E, F)
- Wire up all the electronics using provided schematic(above).
- Load up the code to Arduino.
- Connect 5v power supplies to the two breadboard power supply modules.
- Cross your fingers and fire up the installation!