Laziness is the mother of invention, right?
I have a “garage screen” in front of my garage (very similar to this, if you are not familiar: http://www.alabamasea.com/images/pictures/garage%20screen%20and%20gutters%20003.jpg) - the ultimate purpose is what you can get a REALLY good cross-breeze going inside of your house, all whilst keeping out bugs and random animals that might wander by. Aside from this, it’s kind of a pain and somewhat ugly in it’s “open” position.
Mine has 4 sliding panels in tracks that you have to manually pull open or close. I would like to have this be motorized and ideally remotely controllable.
I’d need a motor of some sort - but what kind? AC or DC? How powerful? I would then do the fabrication and connect a wire/cable (via pulleys) to inner-most door which “catches” on the other panels. In other words, you just need to control one of the outer panels, then other panels “catch” when you open and close.
So I need a motor, something to control it - any suggestions? I have a Fez Spider, a Cobra, a Panda - but any of those can be repurposed - what should I use?
Now the ideal would be (from an aesthetic perspective) to have the screen open whenever the garage door opens - and close when the garage door closes… but then also be able to override when I want the garage open and the screen closed (this is rare, but the main purpose of the screen). So, is there any way for me to have this tie in with the actual garage door opener or the signal coming from my car (I assume this is RFID?)
Any thoughts or opinions on hardware or other facets of this? thanks!
Just about any microcontroller would work, and a simple motor controller based on an L298 would work fine. Alternatively, you could use a 120VAC motor (or whatever is appropriate for you locally) driven via a relay (however, don’t kill yourself with mains voltage!).
The real complexity will be limit switches (knowing when to stop running the motor), but that shouldn’t be too difficult a problem to solve.
I’d probably stick with DC motors, and use something like this: http://www.ghielectronics.com/catalog/product/315 (if you’re going to use the Spider) or something like this: https://www.sparkfun.com/products/9815 if you’re going to use the Panda. If you’re not afraid of soldering, the L298 itself is fairly easy to use and available widely by itself.
Great - thanks!!
Is there any way to detect if the motor is “trying” but not moving? Or - should just create a way to “set” the limits of open and close and do it that way?
Also, any recommendation on specific DC motors? How do I know how big of a motor to get?
You could work it out based on current draw by the motor (which would rise sharply when it stalled), but that would complicate the solution. Simple limit switches are probably enough.
As for sizing your motor, that depends entirely on how fast you want to open and close the screen, and how much friction there is (is the screen on wheels?). Prototyping is in order, probably. Note that using high current motors will affect what motor controller you can use.
An old 12V drill motor might be very close to what you want, if you could find one cheap.
This is great info - thanks again!!
For limit switches, you mean just use a reed switch (mount a magnet on the cable) - and then turn the motor off when the magnet comes into range of my sensor? Or, should I use something like door switches (used in a security system) to know if the panels are opened or closed?
The panels are not on wheels (it doesn’t slide freely) - but it does open pretty easily. However, as each panel catches, that obviously requires more effort.
If it helps, I used a kitchen scale and held it against the knob as I tried to open a panel. To unseat it took about 6.5lbs. The panels fit pretty snug into the catch, when fully-open.
Then, I put the scale on the edge of the panel and pushed. It took about 4lbs of continuous pressure to keep the panel moving. Then, as the next panel catches, that adds about 6 more lbs, as the 3rd and final panel caught - that went above what my scale could measure - but I can extrapolate it would 14lbs. So, I think I need a motor that can move 14 pounds ideally about 1 foot per second.
I wonder, is there some sort of metric that a certain sized motor can move x-amount of pounds?
I’d probably go with the magnetic door switches. They’re simple and effective.
As for motor ratings, I believe you’ll usually get lb-ft or oz-ft ratings (torque). You can do the math to figure out if a given motor is powerful enough. For example, this motor: http://www.pololu.com/catalog/product/1107 from Pololu is rated at 250 oz-in, and by your rough estimate you need ~225 oz, so given a 1" diameter spool, that motor should be powerful enough, in theory (however, I wouldn’t want to cut it that close). It runs at 80 RPM under no load, which would mean it pulls in ~0.7 feet of line per second, given the 1" diameter spool. Clearly, it’s insufficient.
Thanks again so much, I really appreciate your help!!
@ RobSeder - nice project… gotta ask, where did you get the Garage Screen from? All I’ve seen are the roll-up ones and really want one with a frame like you have.
Thanks!
Thanks - I think this could be pretty cool!
As for the screen - I bought this house about a year ago, and the garage screen was already installed. I live in west-central FL and there are several major installers around here. I wonder if you just need to live near the kind of places that install these?
Yeah, this is the first I’ve ever heard of one. I live in the west (UT).
