DIY SmartBlinds V3 With Nema14

This project aims to upgrade the popular DIY Smart Blinds v1.1 with a Nema stepper motor in order to increase the torque for moving roller blinds. For this project, my biggest concern is the size of the Nema motors. The aim of this version is to keep the form factor of the device as small as possible, give it as much pulling power as possible and allow for a standard 12v power supply.

For this project I will use the NEMA 14 Stepper motor. It is small enough at 35mm x 35mm x 26mm. Its 12v and has the torque of 14N.cm (20oz.in.) compared to the 28BYJ-48 motor used in the previous design which is approx. 2.9N.cm. This should make this device almost 5x stronger (based on estimated values from manufacturers specs, results may vary).

• nodeMCU Board
• A4988 Motor Driver
• 12v to 5v Buck Converter
• Nema14 Stepper Motor
• 5.5mm x 2.5mm DC Power Port
• (8x) 2.5mm x 6mm Button Head Screws (for the lids)
• (2x) 2.5mm x 6mm Self Tapping Screws (for nodeMCU mounting)
• (4x) M3 x 6mm Countersunk Crews (for the motor mount)
• STL Files of the 3D model from my website
• Software (links below)

You will require a certain level of soldering skill. There aren't many soldering points. Make sure you take care you don't short circuit any components.

When soldering the wires to the A4988 motor driver, solder them onto the tips of the header pins. This way when you are fitting the driver to the assembly, the wires will not been the way.

You will require to print all the components. They have been designed specifically for 3D printing with out supports. The only tip is when printing the body, print it with a brim. The wall of the main body are only 2.5mm thick and they may not provide adequate adhesion when printing. I normally use a 8mm brim on my Prusa Mk3 i3 printer with a powder coated print bed.

All the STL files you require can be downloaded from my website blog post. There are published there as they constantly change its easier to update in one spot.

Here are the printing suggestions:

• Printed on: Prusa i3 MK3
• Filament used: 3D Fillies PLA+ Marble
• Print mode: Built plate brim for the body only/No supports
• Print quality: 0.2mm
• Print time: 5-6hrs

Before you assemble the device, test it thoroughly. You can upload the Arduino sketch via the micro usb on the nodeMCU. There are plenty of articles on the Arduino IDE online and how to program the nodeMCU so I will not repeat this here.

The nodeMCU software has its own web interface. You will use it to adjust your limits. It also exposes a simple API for integration with Apple HomeKit (through Homebridge) or Samsung SmartThings

Here are the links to the required software:

The assembly of the device is very straight forward. Make sure you prime all printed holes in your model to avoid cracking. Use a 2mm hand drill to clear the holes then gently screw in your screws one by one to thread the holes.

Use the M3 screws to attach the motor to the motor mount, make sure the longer edge is pointing down. The motor mount will slide into the main body. You may need to clear the grooves where the motor mount fits in for a snug fit.

Attach the nodeMCU with the self taping screws, I only used two screws even though the is provision for 4. The driver module should just slide into the second vertical mount.

Gently arrange the remaining components and wires making sure there are no short circuits.

You can mount the device using the supplied wall mount (see STL bundle on the website). This wall mount should be attached to the wall with double sided tape. Alternatively you can use two countersunk screws to attach it.

This device is much stronger than the original DIY SmartBlinds v1. I have been testing it to tilt my vertical blinds and it works flawlesly. The nice thing about the whole device is that it is DIY and any components can be easily sourced and replaced if needed.

You can find more information at https://www.candco.com.au

Enjoy!