Automate an Office Standing Desk With an Arduino and a Mosfet H-bridge

I bought a standing desk from IKEA with a manual handle for lower/raise the desk. Because im lazy and an engineering student, I thought this can be automated. So I got a motor, an arduino, some auxillaries and heated up my 3D printer.

This project is still on going and not finished. All assemblies are just prototypes. I'm looking forward for comments and suggestions for improvement.

Mechanical:

• 1x gear motor
• 3x prototyping boards
• 2x 608ZZ bearings
• 1x 3D printer

Electrical:

• 1x Arduino Nano
• 1x DC-DC buck converter
• 1x limit switch
• 2x push buttons
• 1x leve
• 2x Mosfet IRF9Z30 (Fet P)
• 2x Mosfet IRFZ40 (Fet N)
• 4x Transistor BC547
• 4x Resistor 10 kohm
• 4x Resistor 330 ohm
• 1x power jack adapter

First of all print the parts. You can download the STL files from here or go to my thingiverse page and download it from there. There are the STEP files aswell, so you can modify the parts more easy.

Printer settings:

• motor base: Res. 0.3mm; Infill 40%
• gears: Res. 0.15mm; Infill 50%
• others: Res. 0.3mm; Infill 15%

For the motor base supports are recommended.

The motor group is pretty easy. First put the bearings in place and then insert the gears. Last. screw the motor to the base with M4x16 screws.

I soldered two push buttons on a prototyping board. The board measures 50x20mm (LxB). Two screws attached the board to the controller. Push the LED just in the hole and tighten the level switch in the other hole. Last push the two arrow buttons on the push buttons on the board.

Push the limit switch in the holder so that the switch looks downwards and the screwhole looks up. Screw the holder to the arm and attach everthing the one leg of the desk. Adjust the height that the switch is pressed in the deepest position of your desk.

The H-bridge is soldered on a prototyping board with the size of 60x40mm (LxB) and the Arduino on a board of 70x30mm (LxB). The buck converter reduce the incoming 24V to 5V for the Arduino. It hasn't to be this converter, it can be used any DC-DC buck converter. I just had this one spare. The power jack adapter can be just pushed in the holder. The cabler holder from the base plate broke when i tried to attach the cables, so I've used normale cable holder. In the files here the holders are thicker and I hope they don't break now. In the future I'll do a PCB with the Arduino and the H-bridge on one plate. This I will share here aswell.

The code is pretty simple. When the arduino is ready the LED is permanently on. If you push one button, the motor goes to this direction, if you push the other button it goes in the other direction and if you push the same button again the motor stops. If the limit switch is pressed the motor stops, the LED blinks and the motor goes a bit up the relieve the limit switch.

Now all parts are ready to install on the desk. Put them on a place where you comfortable with. For example i made a hole on the top plate and cover it with glas like in the picture above.