FREE Home-Made Automatic Gate Opener Plans
by Keith G. Vickers
I thought it might be helpful for you if I jotted down a few words about the opener. I spent a lot of time putting that thing together - I'd guess that I've got at least 50 hours of paper design, trial and error, etc. in it. That's quite a bit, but when my wife told me that it couldn't be done, it became a Quest for me. Also, I refused to pay $750 to $1200 for one of the units that would result in me needing another remote control in my car (more on that later).
I put much time into thinking about how I could make a gate opener out of a garage door opener. I decided early on that a screw drive would be easier, and I was trying to figure-out a way to use the screw to expand and contract a "ram-rod" the way the "store-bought" openers do. Then one day I noticed a handicapped door opener assembly on a bathroom door at work, and it hit me that I could use the same type setup to swing the gate, but I would have to mount the opener to the gate, the down side being the extra weight (and resulting inertia during the swing of the gate) and aesthetics. However, I was sure I could come up with a way to make it "pretty" enough for the spousal unit.
My father-in-law had bought an old Genie screw-drive garage door opener at a garage
sale and he gave it to me to try on my gate. It had some sort of clutching mechanism on
the shaft that sticks out the backside of the motor, and it became apparent that this
clutching mechanism was a mechanical way of determining if there was an obstruction in the
door movement. For this mechanism to properly work the opener had to be mounted normally
like it was originally intended. This had to be modified since I planned to mount the
opener 90 degrees from its normal ceiling mount position. This proved to be fairly easy.
If you try this with a newer unit you will not have this problem because the clutching
mechanism has been replaced with a fancy electrical counter which will work at any mounted
position. Also, the limit/stop switches on Genie openers depend on a conventional mounting
to keep them in place, so I tied them with a piece of nylon sting and this has worked
flawlessly for over a year now.
T
here are a few other things worth mentioning about the older opener. The
"T-rail" that forms the screw-drive channel is one solid piece around 9 feet
long. The new T-rails come in two or three pieces and would lend themselves to being bent
easier, but with proper mounting to the gate at the segment joints this should be no
problem.
The mounting assembly for my opener was a solid piece of molded aluminum. The newer units use a lightweight, stamped steel mount which is quite flimsy but absolutely fine for a garage door mount, however it would not work well in my exact application. Again, this is a problem that could easily be overcome.
I spent several hours drawing the whole setup to scale on graph paper in order to determine the best placement of the 4x4 post (the pivot point). Placement of that post is critical for smooth operation of the gate. One thing that is worth noting at this point is that you will want place the limit/stop switches on the t-rail at the most extreme positions possible in order to swing the gate as slowly as possible. I realize that you want the gate to open and close rapidly, but one weakness inherent in using a garage door opener is that the gate can be moving rather fast at the start and stop points. If you have a heavy gate this means the gate will have to stop abruptly and that is not good (by the same token, the gate will have to START to move very abruptly and that is not good either).
According to an engineer at Genie, the trolley moves at the rate of 7" per second, so if the limit switches can be placed 84" apart (as mine are) the gate takes 12 seconds to open/close. As you play with this it quickly becomes obvious to the engineers among you (especially mechanical or structural) that the smaller "angle Z" is the faster the angular velocity of the gate is (I'm an electrical engineer so too much time has passed since I took statics/dynamics for me to model this. It looks like a calculus problem in related rates.) Anyway, because of factors particular to my house I decided that the gate should be going as slowly as possible when the gate was near its closed position and that meant that the "angle Z" should be as close to 90 degrees as possible while considering other factors. If it were possible to make angle Z 90 degrees, then when my gate is swung open angle z would be 0 degrees and it would be virtually impossible to start the gate on the closing part of the cycle. So obviously I had to compromise. The length of the "pushbar" has to be optimized also. From the drawing you can see the measurements and 4x4 placement that I decided to try. I'm sure some crafty mechanical engineer could optimize this and determine a better 4x4 placement and pushbar length, and if one does I request that he/she send me that info.
For my trial run I used several 3/8" bolts/nuts, a 3/8" J bolt, and several
pieces of 2x4 and 3/4" plywood to hang the opener on the gate. I dug a hole for my
4x4 at the placement I had decided on and used a 2x2 board for the pushbar (with steel
sections on each end). To hold the pushbar to the 4x4 post I simply drilled a 3/8"
hole straight down the middle of the 4x4 on its longitudinal axis. I then screwed in a
1/2" lag-bolt (this is still there and working great). The other end of the pushbar
simply ties to the trolley in the same manner as it does in the garage. The limit switch
placement was determined by moving the gate with the trolley disengaged from the
screwdrive (the same thing you do to move your garage door manually). I ran power to the
setup with an extension cord and gave it a try.
I was a little amazed when it actually worked and my wife was even more surprised. My son immediately gave me lots of high fives and thumbs up because now he no longer had to be the palace gate keeper.
I had to immediately jury-rig a stop for the gate at the closed position. My first try was bolting a 4" section of 2x4 to the concrete drive. The gate literally slapped this and bounced a time or two before settling. I decided some springs here might help slow the gate and give it an extra kick when it started the opening cycle. This is still in place and seems to be working fine. I glued some thick rubber to the gate to reduce noise when the gate contacts the springs. I wish I could add some dampening to these springs but so far I haven't figured out a way to do that. I didn't need a stop at the open-gate position because of the grass. The gate hits the mound of grass and this has proven to be adequate for stopping.
I left this in place for several weeks to be sure I could work all the bugs out. I decided to place the 4x4 post in a different position and this lead to making the pushbar a shorter length.
By this time my wife was convinced that this was going to work ok and she was wanting me to make this thing look a little better. I ran the electrical power with conduit and underground romex, and I used a GFCI plug so that I could turn off the electrical power at the unit anytime I needed to. The cover you see in the pictures for the motor end is a black plastic storage container purchased at The Container Store. I cut the top lip of the storage container off and then cut a piece of 3/4" treated plywood to match the outline of the interior. This allowed me to slip the container over the plywood. I cut a matching piece of plywood, and the gate was "sandwiched" between these plywood pieces. The opener motor was then bolted to this, and the container was put over the whole assembly to provide weatherproofing. I used drywall screws to attach the cover. Also, I created an access opening on the backside of the container so that I could access the opener without removing the whole cover. The lid of the storage container provided enough plastic to make a cover for the access opening.
I had recently added one of those Genie secure rolling code receivers to my garage, and I added the identical unit to the gate opener. This allows me to use only one two button remote for the gate and garage. In order to get acceptable remote control range I had to add a piece of coax to the gate receiver and I ran this coax through conduit up to the top of the main gate post. As you can see the whole thing was painted flat black and I think it looks really good.
One problem with my design is that I haven't figured out a decent method of covering the T-rail which gets extremely greasy (it has to be lubricated often, especially after it rains). We have a small, stupid dog which regularly looks out the gate and the top of the dog's head is about even with the greasy T-rail. Result - the white dog has black grease on the top of his head all the time (Goop hand cleaner takes it out whenever I wash him!). Also, the excess oil and grease has caused a greasy puddle near the opener motor, as you can see in the photographs.
If you have any suggestions or questions don't hesitate to email: kgvickers@charter.net
Keith G. Vickers
|
However, if you were lucky enough to find them here first... Congratulations! Yes, these are indeed posted FREE and with full permission of the author. Thanks, Keith!! NH |