I'm building a 25 foot long gate on casters. Due to uneven surface I will be only using two 5 inch castors mounted 5 feet in from each end. I plan on using .062 1.5" square tubing. One of the things I want is to make it as structurely sound as possible. Are there any sites someone knows of that has some info on various truss designs or whatever you can use for an application like this? The gate rolls behind the existing fence like a hidden door.
I will be attaching 5/8 x6' x 6" dog ear planks to it to make it match my existing fence. Am I pushing it by only using 062 wall? The fence is merely for privacy and I just need it strong enough to hold itself up.
Personally, I would go with heavier wall for the horizontals and the verticals at the ends. Put a couple verticals in the interior that maybe can be made to look like posts in the existing fence if that is the effect you desire.
I built a 13 foot long gate that swings on hinges from one side. I used 065 wall tubing and mounted dog eared Redwood boards to the face.
I welded 1 vertical tube in the center of the gate. I also used steel cable and a turnbuckle to create a diagonal member in each of the two cells on the gate. The cable started at the top on the hinge side of the gate and ran down to the bottom of the center vertical tube. Repeated in the outside frame. The gate has been in place for 8 years now. I have no noticeable sag in the gate.
You sound like you might have some experience in this area. :-)
I want to build a swinging gate. The opening is 11 feet. I want to put an automatic opener on the gate so I can drive thru the gate with cars/ RVs etc. BUT, here is the kicker. I want a 3 foot or so wide personel gate too. This walk through gate needs to be part of the 11 foot opening. Have you ever encountered such a setup?
My initial thoughts are to make an 8 foot gate then hinge a 3 foot gate on the end. I would use self closing springs and a stop on the hinge side to force the 2 foot gate to stay in line with the 8 footer. The gate combo would have a stop on the hinge side of things. I am not excited about this idea. I think the gate would be too wiggly with the stop and hinges so close together and
11 feet hanging out in the breeze. Speaking of breezes, we get Santa Ana winds about 3 times a year. Gusts to 60 mph are not un heard of. I would like the face of the gate to be covered in 6 foot high 1x8 dog eared fence boards.
I saw a 20' long swing gate yesterday where the frame was the end panel of one of those heavy pallet racks like you see at the local home center. They are essentially a truss when turned on their side. Currently, they are cheap as dirt of you can find a source. In seattle area there are "the rusty rack guys" in auburn.
May save some build time if you can find one long enough or scab 2 together.
IIRC, in days gone by it was common to have a large gate (or pair that meet in the middle) for the passage of carriages and/or wagons with a small gate built into the gate (or one of a pair) for persons on foot.
And for winter use in snow country, put a solid panel in the bottom two feet of the opening, then the swinging portion won't normally get frozen closed. Gerry :-)} London, Canada
You might consider a three piece gate. A double gate between two posts, then a small one piece gate on the outside of one of the posts. Trick is to get a MONDO footer for the post, and a post substantial enough to hold the gates. Or, you could make a mini gate into one of the two panels, something like a small door. But the down side of that is you have to step over the bottom of the opening, and under the top.
Most notably, it will have low torsion stiffness. This is the same shape the Wright brothers used for their warped-wind roll control.
Adding steel will just make a heavier noodle. If you could add a third member half way up, as little as a foot from the plane of the other two, and triangulate, that might be rigid.
I'd weld it up out of thin wall, and laminate the long members with polyester and graphite. Poly for low toxicity (epoxies can be irritating) and graphite for stiffness. The plies should be at a 45 degree helix angle, in both directions, that is, alternating left and right hand spirals. For hand wrapping these spars, long strips of cloth or mat would do, while parallel fibers would just be too much work.
They made the spars for the human powered airplane out fo graphite fibers, IIRC. They were vacuum-bagged onto aluminum tubing and after curing the aluminum was etched out, leaving a long, light, stiff tube.
Such a tube has more sag than your trussed gate, but great torsional stiffness. For an efficient wing, sag is no problem, but any change in design angle of attack ruins performance. The thing flew at optimum L/D to the side of lower drag the whole way across the Channel.
The torsional stiffness helped control the L/D over the entire length of the wind by making all attitude changes reflected by angle of attach changes. That's called controllability, and lack of it, just as STeve wrote, is a noodle.
Yours,
Doug Goncz (at aol dot com) Replikon Research
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