Introduction: Power Pocket Door
Things you'll need:
Lumber - enough to frame your door, & wall out to 6" as measured without drywall.
Pocket door track - a high quality one, that no matter how you push the door, you can't derail it.
New door - you're going to want a wider door than the one you've got - i used a 36" door, because a couple of inches of it are wasted when the opening edge goes into the wall.
250 Watt Scooter motor - yes, this is overkill. The first power pocket door i built, i used the same sized motor, but it was a 1 3/4" thick solid core door (140 pounds!). Still, even with a hollow door, i wasn't satisfied until i upgraded to this size motor.
250 Watt Scooter motor controller - they're cheap on ebay, & it's much less headachy than building one from scratch.
2 12 volt batteries -- They don't have to be particularly big - you could use ones from a UPS, or whatever - i bought mine new at Home Depot for like $26 each. I could have ordered them off ebay for a LOT less, but I was impatient. Just remember you want sealed batteries, or you'll have acid venting into your wall
24v charger -- ebay this too -- they're cheap, & again, much less of a pain in the butt than building it yourself.
2 Arduino Uno's (or you could use Nano's - i'm using one of each, 'cause i wanted to add sound to mine, so i used a sparkfun vs1053 mp3 / sd shield.
you're choice of buttons, or switches or whatnot to activate it. in the past, i've used pressure switches (one even had a counter that counted up, then back down when you passed thru the other side, to automatically close the door once the last person went thru). i've used lasers with CDS cells to trip the door, proximity sensors, IR motion sensors, even video cameras that had a motion zone to trigger the door. in the end, my current door i've got pushbuttons, 'cause it's so much more reliable, & simple. I am trying to get an interface going using a raspberry pi3's wifi, hopefully controlled by an app on my android phone..... eh, i'm never satisfied.
at least one roller skate, or skateboard (not an inline skate either - gotta have those wide wheels the old school skates have). These are used for pinch rollers to open & close the door.
6 feet of steel box tubing - again, home depot.
6 feet of 3/8" all-thread rod - home depot.
other misc hardware that will be covered later.....
This isn't for the timid - and though none of it is actually difficult, it can be a somewhat overwhelming project when a wall of your house seems gutted due to lack of drywall. If (big if) you get everything together before you start, & build some of the small stuff first (like mounting the motor & idler wheel to a board first), you could easily have this done in a day. If you've got to keep running to home depot, or ordering parts, well - it could take considerably longer.
Step 1: Frame & Hang Your Door.
Frame in your door. This requires some knowledge of carpentry, drywall, painting, & electrical work.... but even if it's your first time, it's not that difficult. Just remember, you're going to need room for the motor, so I framed out my wall with 2 x 6's. There are plenty of websites out there that can show you how to do this. My only suggestion for a motorized pocket door, is to use the same door hanger as I did. The reason is, that no matter how you push on the door, you can't possibly remove it from the track using this setup. Their website is here....http://www.johnsonhardware.com/200pd.htm & you can order it directly from them, home depot, or wherever you like. Once you get the door hung, don't put that sheetrock back on yet, because you've got a lot of stuff still to do.
Step 2: Situate the Motor & Push-rod
You're going to need some interesting stuff here. A trip to Home Depot alone isn't going to cut it. Though you can get most of what you need there, unless you happen to have an old pair of roller skates laying around with good urethane wheels (not inline skates either - the old school kind), or an old skate board that you can get the wheels from. My wife stopped at one of the local thrift stores & scored me a pair of skates (6 more wheels than I needed, but hey, they'll come in handy for something) for $5! The tie bracket & corner brace, along with a 6 foot piece of 3/8" all-thread rod, & a 6 foot piece of 1/2" steel box tubing, several nuts for the threaded rod, & washers, and most importantly, two washers that will replace the bearings in one of the wheels. The diameter of the washer needs to be the same size as the outside of the bearing that was in the wheel, while the hole in the center needs to be slightly smaller than the shaft of the motor (so you can file a D shaped hole in it that slides over the shaft). The best way to do this, is get a fender washer with slightly smaller hole, file the hole into a D shape that just fits over the shaft, put them on the shaft & put a few smaller washers to hold them in place, tighten the nut. Then temporarily hook them to a single battery, & slowly & carefully apply a file to the edge of the washers, until the outside edge is round & centered, & just slightly larger than the bearings. You want to almost have to hammer them into the wheels. Remove from the motor, remove the bearings from one wheel, & put the washers in. Make sure you align the D's on the outer & inner washers when you do. Then mount the wheel on the motor. When it spins, it should be centered & not wobbling. Next, take the corner brace, & drill a hole in the upper corner big enough to put a bolt just big enough to bolt another wheel (with it's bearings in it) to the brace. You may need some washers on the bolt before putting the wheel on, to space the wheel away from the bracket. I took about an 18" scrap piece of 2 x 6 & mounted the motor & the idler wheel bracket to it, using the box tubing as my guide. You want the box tubing to fit tightly between the wheels where it can't slip.
This is an over simplified wiring diagram of my setup. basically, you could do this all with one Arduino - the reason i chose to use two, was so that one would work as a sound generator (to play the Star Trek Holodeck door sound when the door is opened or closed). since i needed more pins than were available on an arduino with an mp3 shield,i decided to tie two of them together & use the wire library for communication between the two. You don't have to use the 8 relay board like i did - in fact, you can use just two relays, just so long as they have 5v coils, & the contacts are rated at at least 24vdc, @ 20 amps. on my setup, i used 4 relays (because they're only rated at 10 amps each, so i wired them up in parallel to double the amperage). be prepared for them to get "stuck" at least once during the first couple of uses --- after that, they shouldn't get stuck again. a quick thump with the butt of a screwdriver will unstick them, afterward, there shouldn't be any trouble.
Step 4: Dial in Everything
the more smooth the mechanics of your setup work, the easier it'll be for your code to be consistant. i was originally planning on using an optic reader, to measure lines i used a magic marker & put on one side of my box tubing. as the tubing passed by the optics, it would send a pulse that the arduino would count, & use as positioning data for controlling the speed of the motor, & know when to shut the motor off. i still may go back to that eventually, but as for now, i just used a microswitch to sense when the door is fully shut. This was so i could have it lock a solenoid to physically lock the door shut. i still have yet to implement this on my door. What can i say, it's a work in progress. one trick i learned here, is the board that has the motor & idler wheel mounted to it. once you have the wheel on the motor, & the idler wheel parallel & opposing each other nice & straight, the way to make sure the box tubing pushrod stays between the wheels, is to mount the motor board to one of the studs, & then put shims under one side of the board or other, to make the wheels perfectly perpendicular to the box tubing. if it's even a little off, the pushrod will track one way when opening & the other way when closing, eventually trying to jump out from between the wheels. of course, it can't jump out, because it threads thru at least one hole drilled in a stud (and the motor board), but it will push up against the sides of that hole, creating considerable drag (and noise). it's not hard to shim it out where it'll track in the same spot every time. i used paint stirring sticks as my shims, your mileage may vary. Had i thought i was going to write one of these pages, i would have taken pictures at every step --- or at least before i re-hung my drywall. if anyone needs help with a particular step, feel free to contact me at firstname.lastname@example.org. I'll do my best to help you as i can.