In a world full of gadgets, the common maker is in their element. Instead of seeing an everyday home appliance, they see potential projects.
There is one home item in my house however that is still living in the past, my curtains. As we are renting, no changed are allowed to be made to the property. So how does one bring their curtains into the 21st century whilst still keeping there an intact? How about adding an Arduino powered automation system?
I decided it was time for me to finally have a go at modernising my curtains. I've thought about how I would do it before, but felt that I had neither the technical ability nor patience. This project is showing me how far I've come in the Arduino world and how things that I once saw as incredibly complicated are now 'simple'.
If you would like to see the build video for the project, you can do so below. If videos aren't your thing however I will write about the process below that.
The first thing I do when starting a project is seeing whether someone has done something similar. Googling 'automated curtains arduino' returned a number of responses and even an instructable. The thing that pleased me though was that they were also using the same type of curtain system. They were using the curtains that are raised and lowered by a looped cord. My curtains are incredibly primitive and just slide back and forward on a curtain rod. I knew that there was more that would be involved in getting mine to work but that is always half the fun.
I began designing a system with a pen and piece of paper. Having just built a 3D printer I thought of using a form of belt system to pull the curtains open and close them. Belts, however, are expensive, particularly for how long I needed it. Plan B, use my sailing experience to develop a rope and pulley system (don't let a boatie hear you call them ropes, on a sailing boat they are called sheets). The plan now was, have a base station on one side of the curtain rods with a large drive pulley wheel. On the other side of the curtain rod I would place an idler pulley. The thing with rope is though that you can just loop rope around and expect it to act like a belt. You have to loop it around several times in order to give it the traction to pull upon itself, also making sure the rope is tied at either end. I like the rope and pulley design as it could open and close my curtains at a relatively fast speed with little force required.
Now that I had the basic idea drawn down I then had to design the main control box. This would be a box that would slide onto the curtain rod that contained an Arduino for brains and a continuous rotation servo to drive the main pulley. I opted for a cont. servo over a DC motor as they have a larger torque output due to the internal gearbox and are also easier to mount. Cont. rotation servos are also considerably easier to power and control, whilst using a DC motor would require me to use a motor driver IC or some transistors. Both of these options take up space which would be limited.
I mocked up a quick design of the control box whilst making rough measurements to get an idea of how big it needs to be.
On the other side of the curtain rod I need an idler pulley, something that is not actuated, but gives the rope something to go around. I designed two pieces for this. The first piece slides onto the curtain rod and has an 8.5 mm hole on top to allow a small length 8 mm smooth rod. The second piece is the actual pulley wheel. This was designed with a cutout that would allow an 8 mm skate bearing to be placed inside of it. Whilst a bearing wouldn't necessarily be needed, I had some lying around and thought it’d be best to use them to increase the longevity of the part and decrease any potential resistance on the system.
Once these were designed on paper it was time to digitize them, I did so using Solidworks. I designed the main control box to be 3D printed face by face. Printing face by face allows me to make adjustments if something was wrong and only have to reprint one face instead of the entire box. Each face had tabs which would slide into each other allowing for a friction fit (I believe these are called finger joints). Once these were designed I printed them on my home made Prusa i2.
The end pulley mount and wheel were easy to design.
Both the end pulley mount and main control box needed something to stop them from tipping upside down. Again, building the printer taught me a few things. Using the same grub screw technique used to attach the pulleys to the steppers on the printer, I used a screw and nut trap to hold the mounts onto the curtain rod.
Once everything was printed and attached onto the curtain rod I ‘acquired’ some rope. This was looped twice around the drive pulley and once around the idler pulley. I pulley the ends of the rope together, making sure it was nice and tight and cut it. A simple knot was all that was needed to join these two ends together.
Spinning the main drive pulley by hand moved the entire rope system. Phew, my idea works. Clothes pins (or Pegs as we call them in Australia) are used to attach the end points of the curtain onto the rope. One curtain was attached to ‘giving’ side of the rope and the other to the ‘receiving’ side. Spinning the drive wheel one way pulled one curtain towards it and the other away from it, opening the curtains. Spinning it the other way had the opposite effect and closed them.
Now all that is left to do is wire up the system adding a form of wireless communication followed by some programming. I’m opting for Bluetooth as the modules are very inexpensive and the maximum operating range is well within the confines of my room size. It also allows me to control it from both my computer and phone, whereas a system such as IR would require me to use a specific remote.