The Basement.

 This is the trap door to our basement. As you can see, we have a block and tackle to open it. It is VERY heavy. Then when we do go in, it is VERy dark down there.

Let there be light

The darkness was easy. Just a contact sensor and some Hue lights bulbs.

You may remember, from my post on the double doors on the wardrobe, that one of the issues I've seen with contact sensors is the strength of the magnet. Even with a door, I found that I needed a strong magnet. With these trap doors, the tolerances were even worse and so I had to get inventive. Fortunately, the Eve Door & Window Sensors come with some extra capabilities to build out the magnet and so I could get Trapdoor and frame to align.

The automation of this was very easy.

I created a group called Basement Ceiling, and then created two automations that turn on the group when the contact sensor detects no contact and turns off the lights when contact is regained.

That's a bloody heavy door!

As you saw from the earlier picture, the door has block and tackle to open it. It is a very solid construction. Whilst that solution does work, it's not exactly pretty and it removes space from the rear deck. This, unfortunately, is where I start to get into what I'm going to do about something rather than something I've done.

I noticed this video a few months ago:

You'll notice that the design of the doors is very similar to my own. So I contacted the company that produced the video, Progressive Automations. They have an interesting blog article on how to do this, but it does not go into a great deal of detail.

What is interesting, though, is that they have a Remote Control capability that works over WiFi, and so I think this could be perfect for a Homebridge plugin. Unfortunately, they will not publish the API as they insist it is proprietary. This attitude is a shame as it really limits the capability of the product for home automation. They do, however, have an RF module as well. So I'm thinking I could use that until they come to their senses.

This isn't going to be as easy as it seems though. I have to do quite a bit of measuring, including the weight of the doors. I'll update this as I actually do the work. The cost does not look like it will be that high, as the actuators are only $150 each (PA04 which have IP66 rating).

Success!

I've actually sold my house, but I did managed to do one door.

The important information is the calculation... and it's hard! I ended up getting into quadratic equations, which is something I haven't done since I was at school (That's High school!)

This is the page you need on Progressive Automations. It's called, ironically, "Simplified Calculations for choosing Actuator Parameters".

You must know the weight of your door. Not so easy when your door is already installed. I actually bought a RoMech Hanging Scale, and lifted the door with that. It told me that the door was 40kg, or 88lbs.

With the Progressive page, you need to go to the Actuator Force Section which then give you the force that the actuator must be able to push.

Then you need to go to the Rotary Motion section. The diagram isn't quite right for this example, as it shows taking a door from closed at vertical, to open at horizontal. We actually need the opposite. It doesn't make the diagram invalid, but it's easier if you look at it like this:

The problem with this diagram though is that it is too simplistic. It doesn't show you a few key elements you have to take into consideration:

1. the thickness of the door and 
2. also the depth of the mounts.

These are important because the centre of the linear actuator is not inline with the hinge, as shown in the diagram. The door in my case is 16cm/6.3". Then there is the distance from the actual door or wall to the centre of the mount which was about 6cm/2.4".

That means that, in this case, the top of the X1 measurement was not at the same horizontal point as the hinge, but was actually 22cm/8.7" lower, it also meant that Y1 was further in to teh stair well than the wall itself.

This caused me to do a lot of unnecessary drilling as I couldn't understand why my measurements were not correct. Fortunately, it didn't affect the length of the actuator needed.

I ordered the following:

• PA-04-16-400 linear actuator, which is rated at 400lbs and has a 16" stroke.
• 2 x BRK-02, the mounting brackets.
• PS-20-12, dual voltage power supply with 12vDC out and up to 20A.
• PA-33 Control box, also 20A, and delivers an RF signal.

This, though, is the end result integrated in with HomeKit:

The integration with HomeKit was achieved using the homebridge Broadlink RM plugin and configuring it as a Garage Door.

A few pointers:

• I set autoCloseDelay to be 12 hrs, which is 43200 seconds.
• type is garage-door-opener as it was the closest thing I could find.
• openCloseDuration is set at 23 seconds, which is how long it takes to open or close.
• There is a bug in the plugin where garage door openers show up as thermostats, there is a patch available to fix that. Go down to the command line and type:

npm i -g https://github.com/dnicolson/homebridge-broadlink-rm#fix-service-types

{

            "autoCloseDelay": 43200,

            "debug": true,

            "data": {

                "close": "<insert close hex code here>",

                "open": "<insert open hex code here>"

            },

            "host": "192.168.1.247",

            "type": "garage-door-opener",

            "openCloseDuration": 23,

            "name": "Basement Door",

            "persistState": true

        }

Getting the hex codes is done through using the scan and learn buttons in Homebridge. The hex codes appear inside the homebridge log.