Help me design a cheap automatic door opener

The pneumatic rods look like one important piece of the solution. You still would need to design a system of levers and hinges for opening and closing the doors. This is where your budy with the machine shop would come in. It would be best to keep the cylinders as short as possible to keep the ugly factor down as well as keep them from getting in the way.

Using the cylinders on sliding doors could be very easy, except that the easy way of doing it would mean the cylinder would be as long as the distance the door slides (when compressed) and have them mounted out in the open (ugly factor again). Since you have new construction, perhaps you could have them put your door header several inches higher than the actual door leaving you a nice space above the door to hide your gizmo. If you were ok with voiding your door warranty, you could cut a slot in the top of the door frame and have a bracket that attaches to the top of the door and goes through the slot up into that extra space above the door where you would attach to the hidden cylinder. You would need to use a piece of trim at the top of the door that could be removed for servicing.
 
Wow! Looking through the McMaster catalog is getting me super excited, but honestly just as overwhelmed.

I'm finding all kinds of products that seem like they'd be perfect for my application, but having a little bit of a hard time putting all the pieces together and figuring out exactly what product numbers I'd need. Is anyone here (signal15 maybe?) familiar enough with the McMaster catalog/their products/and doing a project like this that they could help me figure out what part numbers I'd need. I've looked through all the ball pivots, flow regulators, solenoids, valves, etc. and know that they have the majority of what I'd need, but have no idea where to start to pick out the exact pieces.

Maybe I should just wait until it stops raining and roll my wheelchair down to the fabrication shop, but if I had a few parts to hand him that would at least get things going.

The rodless air cylinder looks so sweet. Honestly, I'm sure I could hide them in the door headers, but they look so neat with their industrial aluminum look I think I'd almost like to have them out in the open so that I can make the cool industrial look part of my decor. Maybe I'm crazy, but I think they look pretty neat. As for the swinging doors, one of the other members sent me a link to a company in New York that is doing exactly what we're talking about with pneumatic cylinders. Looks like we should be able to get away with an 8" cylinder which should really be quite cheap; maybe 50 bucks or so for the cylinder.

Check out their product at: http://www.gentlemandoorcompany.com/double...g_operator.html

I've reached out to their owner to see if he might be interested in helping out.
 
MIKE I also posted this on your blog but figured I'd do it here also for everyone else to see.


Mike,

What about using the linear actuator, and measuring the current being drawn for your safety mechanism, and reverse polarity a bit and then kill power for a safe extraction of foot/finger...Also on the realm of manual operation, what about some electro-magnetic connection... energize the electro-magnet to stick the mechanism to the door and de-energize it and it can open manually. (so keep it de energized until you want to use it.

I think that with pneumatic option you'd still have problems with the snow load up there unless all doors open inward (thinking storm doors also could be a problem…) and if any snow gets in the door seal it may not close in any case, so if the safety mechanism trips it should also set off an alarm of sorts.

Todd
 
Hey Todd,

Thanks for posting both places... I'm finding there is a much different audience at the blog then around here.

I keep going back and forth between the pneumatic/all electrical solution. In one sense I love the simplicity of tuning the speed/strength of a pneumatic system. Throw in a pressure regulator and flow control valve and you immediately have fine control over the whole action. I would much prefer an all electrical solution for cleanness/simplicity/not having to run air plumbing everywhere, but am struggling with a few characteristics of an all electrical solution. Seems to be far more challenging to integrate and keep things safe.

I like your thoughts about finding a way to make a linear actuator safe. I will admit still, I have always been hesitant to rely on an electrical system alone to keep an inherently non-safe system safe. As for your electromagnetic connection, I've been doing some research on a device called a hysteresis clutch which is exactly that. Haven't turned up exactly the magical product to solve all my worries yet, but it looks like some sort of hysteresis clutch combined with a gear reduction motor could definitely fit the bill for the swinging doors.

For the sliding doors it's looking more and more like a linear actuator belt drive with a properly sized torque tensioner/override might be what I need.

It's just a challenge figuring out what products/vendors to look at. There are literally thousands of different products with hugely varying prices and specifications.

Will keep looking tomorrow.
-Mike
 
Does anyone here know much about linear actuators?

I had always been under the assumption that they are an all on/all off type of device where you have little control over the force of the device/motion. As I've researched them more this seems to be completely wrong. Would I be able to set the force output of a linear actuator to a low enough level such that if an arm got in the way of a closing door the operation would stop?

A company I've been looking at a lot is called Tolomatic. Their products seem pretty impressive and can be found at: http://www.tolomatic.com/
 
Does anyone here know much about linear actuators?

I had always been under the assumption that they are an all on/all off type of device where you have little control over the force of the device/motion. As I've researched them more this seems to be completely wrong. Would I be able to set the force output of a linear actuator to a low enough level such that if an arm got in the way of a closing door the operation would stop?

A company I've been looking at a lot is called Tolomatic. Their products seem pretty impressive and can be found at: http://www.tolomatic.com/


I was considering a similar project at one point and looking at this site: http://www.firgelliauto.com/
There was someone here that has a company that creates automation boards based on CAN (Controller Area Network), but I think he decided that there was not enough interest to proceed with development of the board I needed from him.

These threads might help (or discourage :( ) you:
http://www.cocoontech.com/forums/index.php...linear+actuator
http://www.cocoontech.com/forums/index.php...linear+actuator

I've abandoned the project for the time being, but I'm very interested in how yours turns out.
 
The window regulator in my car broke so I replaced it yesterday. Anyway, it got me thinking, a car window regulator (that is what the mechanism is called that raises and lower a car window), could be modified to open/close a sliding glass door as well. Most use a cable that runs around a pulley that is turned by an electric motor. The cable wraps several times on the pulley for traction but the total wire length is whatever you want. I think you could move a sliding glass door using a modified one of these and you could probably pick one up at the salvage yard for next to nothing with the switch and all.
 
Thanks for keeping up with the status of this project and adding your input.

The whole building a house, acting as the general contractor, designing/integrating the control system, all while paralyzed from the armpits down has become more of a full-time job than I could have possibly imagined! I have decided to put my desire to design my own automatic door opener and the research theirin on the back burner until the house is completed and life possibly a bit more tame/less crazy. To help serve for this possibility in the future I did run contact sensors to each door and a 4 conductor/16 AWG wire that is hidden in the door jam of each location I'd like to automate. Hopefully as time allows and I've worked out the details of my overall automation system I can pry off the trim boards, access these hidden wires, and have at designing my own system for far cheaper that is commercially available.

At that point I'll make sure to update this thread and look forward to all of your input.

Thanks for everything!
-Mike
 
"mounted out in the open (ugly factor again)"

Just put a wooden valence around it.

As for safety, you can put a pressure switch in, set it to trip where you want it to...this could cut the power to the valve, thus purging the cylinder's pressure. Or, have it trip a relay that would reverse the pressure and open the door (personally, I'd rather it go limp...but if you look at a garage door opener, they are designed to go all the way back UP if they hit anything on the way down).

I wouldn't use those linear slide cylinders...expensive. At those prices, I'd just buy the kit from the website listed a few posts up. Just get a bimba cylinder. Then have a valve with a pressure switch on it. The valve gets wired to your "switch" or automation stuff.

as for unlocking...for sliding glass doors, there are electrical releases for the door locks, but I think I'd rather go with a mag lock. There's a kind that will pull OUT of the door.

Basically, the magnet is put in the header. Then there is a part that slides up and down. This is installed IN the door, at the top (you route a hole for it). Then, when the door is closed, the magnet pulls the sliding mechanism OUT of the door, into the header...we are talking 1" of travel at most...but this way, the mag lock can be small, as it's not the magnet's force you are pulling / pushing against, but the slid mechanism...

http://www.sdcsecurity.com/class.aspx?id=2

The Shear 1560 is the one I'm talking about. The magnet part goes in the header, the other part goes into a hole you cut into the door. Then that part will slide up and down. Plus, it's fail safe (you battery back it with a kill switch at the door for emergency egress).

Hmm...neat, I don't remember the 1561...looks like you don't need to cut into the door for that one...bolt it to the door...nice.

--Dan
 
How about this from Skylinkhome:
It's an automatic door opener for up to 100lbs. It's $260

http://www.skylinkhome.com/us/products/sdo/dm50.html
 
How about this from Skylinkhome:
It's an automatic door opener for up to 100lbs. It's $260

http://www.skylinkhome.com/us/products/sdo/dm50.html

Now that one is a no-brainer. For $260 I don't know how you could touch that even building it yourself. And you could wire the keyfob to a relay on your HA system to control it from there as well.
 
Only issue I see is no sliding glass (that I saw) and looks to be for interior doors (doesn't look like it has the power to close an outdoor-door).

Other then that, I agree, for that price, you can't touch it even building it yourself. Heck, maybe it's on e-bay even cheaper!

--Dan
 
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