Step 2: Print and Assemble

When you have Electronics, Mechanics, Mold, Software, let’s assemble the robot!

3.1. Electronics

3.1.1. Principal scheme

Be ready to solder pins and mount elements to the breadboard! You need external power source voltage of 12 Volts, which provides at least 1 Ampere. Power line is protected by a fuse with nominal value of 2 Ampere.

DC-DC converters D1 and D2 organize two channels of voltage. D1 is for Arduino Nano D3 and Bluetooth module D4, D2 is for both servos. Use voltmeter to adjust converters so that D1 provides output voltage 5V, D2 provides output voltage 7V.

Module Bluetooth D4 pairs your smartphone and the robot. We use UART interface to provide data exchange between Microcontroller D3 and Bluetooth module D4, see RX and TX. Arduino Nano D3 controls servos with outputs D5 and D6, through the resistors R2 and R3. See jumpers JMP1 and JMP2. For normal functioning of electronics JMP1 and JMP2 must be installed. Before uploading new firmware on the microcontroller D3, remove JMP1 and JMP2.

If you have experience how to solder elements on PCB, do it yourself according the principal scheme. Otherwise assemble electronics on breadboard using Table “Elements on the breadboards (SB DIY)”. Be very attentive with all digits and letters!

3.2. Mold

Use 3D printer to print mold.

3.2.1. Download SelfieBot mold STL files at: https://pinshape.com/items/22311-3d-printed-selfi... or https://pinshape.com/items/22311-3d-printed-selfi...
3.2.2. Use Cura (download Cura) to convert SelfieBot mold STL files into GCode for 3D printing.
3.2.3 Launch Cura app. and open downloaded STL files one by one pressing the LOAD button in the upper left corner of the model view window untill you will fill the printing area.
3.2.4. You may use your usual 3D printer settings for SelfieBot mold printing. Prefered printing settings for Wanhao Duplicator i3 with Nozzle size of 0.3 mm using PLA plastic in Cura are:
Quality: Layer height (mm) - 0.2 Shell thickness (mm) - 0.9 Retraction is enabled

Fill: Bottom/Top thickness (mm) - 1 Fill Density (%) - 20-35 (any of this values are usual)

Speed and Temperature: Print speed (mm/s) - 30 Printing temperature (C) - 210

Support: Support type - Touching buildplate Platform adhesion type - Raft

Fillament: Diametr (mm) - 1.75 Flow (%) - 100.0

Retraction: Speed (mm/s) - 40.0 Distance (mm) - 1.5

With these recommended settings you will need approximately 400-450 grams of PLA plastic if there would be no oveprints in case of printing process damage.

3.2.5 In a menu FILE press “Save GCode…” on a flash memory device compatipble to your 3D printer (microSD flash memory card for example).
3.2.6 Insert flash memory card in your 3D printer, and print files according to your 3D printer instructions.

3.3. Assembling.

So you have details (see the picture above):

NB: Servo motor shaft caps, Frames and Bracket are metal.
Important! When electronics are ready, connect the servo motors pllugs to it and turn the SelfieBot on connecting it to supply power to set the servo motors in a zero position. Then turn it off and disconnect the servo motors plugs.

3.3.1. Prepare the crosshead screwdriver, tweezers and pliers.
3.3.2. prepare 26 screwnuts 3 mm diameter and 7 screwnuts 4 mm diameter.
3.3.3. prepare countersunk head screws 3 mm diameter: 10 mm - 8 pcs. 16 mm - 8 pcs. round head screws 3 mm diameter: 8 mm - 2 pcs. 16 mm - 6 pcs. 20 mm - 10 pcs. countersunk head screws 4 mm diameter: 25 mm - 6 pcs. (you may need more screws - it is up to you).
3.3.4. Screw part #1 with part #2 using two 4 mm diameter screws and two screwnuts.
3.3.5. Screw parts #1 and #2 with part #3 with at least four scwews and screwnuts 3 mm diameter.
3.3.6. Screw the frame for a servo motor using two screws and screwnuts 3 mm diameter.
3.3.7. Screw the servo motor with a frame with its shaft to the up in the center of a round part #3. Be sure the servo cord is located in a low compartment.
3.3.8. Mount the round cap on the servo motor shaft and screw it with a 3 mm diameter screw.
3.3.9. Mount part #4 with a second frame for a servo motor on it.
3.3.10. Screw the round cap of servo motor #1 using four countersunk head screws through the second frame.
3.3.11. Put the second servo motor cord to the low compartment and screw it to the frame.
3.3.12. Screw 3 mm diameter round head screw through 4 mm diameter screwnut to the frame at the servo motor shaft level from the other side.
3.3.13. Mount the servo motor shaft cap and then mount the bracket on the shaft from the one side and to the 3mm screw with 4 mm screwnut from the other.
3.3.14. Screw the bracket to the servo motor shaft cap.
3.3.15. Mount parts #5 from both sides of the bracket and screw it.

4. Mount electronics and connect servo motors to it. Power on. Test electronics and servos via SelfieBot Droid program on your smartphone.

5. Screw the bottom #6 with 4 mm diameter screws and screwnuts.

6. Mount part #7.

7. Use any common mobile device cradle. If you will use a magnet holder, you will need a Magnet cradle holder part attached to all STL files for 3D printing on links https://pinshape.com/items/22311-3d-printed-selfi... orhttps://pinshape.com/items/22311-3d-printed-selfi...

Looks great, isn’t it? Good job!