What is a gate?
April 8, 2019 3:31 PM   Subscribe

It’s a home improvement question, but really a physics question.

House has an 8 foot wooden fence. Previous owners created two gates by removing bits of fence and screwing a long board across the back. Then they added little hinges. Both gates are wider than what I would guess is standard, one is about 6 feet wide and one about 10.

Both gates are the same height as the fence, so you need to drag them across the ground, and they’re both incredibly heavy. The hinges are all either straining or fully pulled out of the “wall”.

Imagine I have like $200 total for this. What does it take to make a gate work? My first thoughts are longer hinges and shortening the wood that makes up the gates so they don’t drag, but I have no idea what a gate is supposed to be and clearly neither did whoever built this.
posted by OrangeVelour to Home & Garden (20 answers total) 2 users marked this as a favorite
 
I'm guessing that since it's 8 feet tall, it's a privacy fence? How important is retaining that aspect of it for the gate?
posted by dbx at 3:44 PM on April 8, 2019


would this kind of thing help?
https://images.app.goo.gl/SuuNWFwcxHKJ73zq9
posted by superelastic at 3:47 PM on April 8, 2019


Gates need gate posts: heavier, taller verticals driven deeper into the ground that the regular supports so that the gates won't sag. The gates themselves need thicker verticals to take the forces from the hinges, and also some cross-bracing so they're not just floppy parallelograms.
posted by scruss at 3:48 PM on April 8, 2019 [8 favorites]


Response by poster: Privacy is not important, but thanks for teaching me the phrase “privacy fence.”

These gate posts... they go at the edge of the fence where it meets the gate?
posted by OrangeVelour at 4:04 PM on April 8, 2019


To make a physics /statics comparison, ya know how when you solve a physics problem you can and should apply assumptions to simplify the math? Like how you'd assume no bending if analyzing a beam (until you learn how and when to calculate bending moment and maybe shear failure and modulus this or that)?

Yes, don't do that with a gate that you want to not drag along the ground or, heaven help you, latch nicely. I'm decently handy and I overengineer gate post and hinge construction far above what I would for most anything else. Otherwise, you guessed it, that sucker will sag or twist and you are right back where you started. The heavier the gate the more you go overboard.

All of these are good or baseline requirements:
Bombproof perfectly vertical gate posts in concrete.
Large hinges. Perhaps silly large.
Z frame gate construction with bracing on corners.
Tesion wire with turn buckle going from upper hinge locale to lower cornerthat you can adjust in coming months.
Use screws, not nails even in non hinge locations.
Plan for it to sag a tiny bit anyway if you are positioning a latch so you don't run out of play and have to do an ugly move after all is said and done.
posted by RolandOfEld at 4:17 PM on April 8, 2019 [10 favorites]


Also some gates say fuck it and just put a little wheel caster assembly on the far end from the hinges because that's easy mode compared to getting all the things that I said just right. Not to mention that once you hit a certain weight/length (because physics) you be spending thousand bucks and/or using metal bracing to even be in the ball park of the rigidity you would require for no sag without a caster supporting that corner.
posted by RolandOfEld at 4:23 PM on April 8, 2019 [14 favorites]


Once you've got beefy enough hinges and posts isn't it possible to add counterweights to make the movement easier and smoother? Now I want to build a gate.
posted by XMLicious at 4:28 PM on April 8, 2019


Check out Fences, Gates and Bridges and How to Build Them, George Martin, has been reprinted a lot, has a lot of illustrations.
posted by clew at 4:38 PM on April 8, 2019 [8 favorites]


I'm with Roland, I'd be looking at wheels were i you.
posted by Dashy at 4:41 PM on April 8, 2019 [1 favorite]


One thing for wheels on the gate is if it is going over a hard surface like a deck or concrete you'll be OK but if it is going over grass or soil then you'll want to put something hard underneath where the wheel will be travelling because otherwise the wheel will just wear a trench and the gate will sink in and you'll be back to where you are right now.
posted by any portmanteau in a storm at 4:54 PM on April 8, 2019 [4 favorites]


Split the gates in half so that they are easier to open? Is that what you were thinking?
It's nice to have wide openings, when you need them, but splitting them in half would make them lighter and easier for everyday use, sort of a wicket gate.
posted by Bee'sWing at 5:21 PM on April 8, 2019


Check out Fences, Gates and Bridges and How to Build Them, George Martin, has been reprinted a lot, has a lot of illustrations.

Here's the Gutenberg version, directly linked to the chapter on gates.
posted by zamboni at 5:52 PM on April 8, 2019 [8 favorites]


Can the gate be a frame with mesh, not heavy wood?
posted by theora55 at 6:01 PM on April 8, 2019


Do make sure the posts are sturdy enough to handle stronger hinges, sucks to build up one part an have another just sag or tip over.
posted by sammyo at 6:10 PM on April 8, 2019


Consider adding cable support.
posted by sammyo at 6:12 PM on April 8, 2019 [2 favorites]


If you get gate casters with spring loading and a large wheel with a soft tyre, they will take quite some while to wear enough of a track to become ineffective even if they're running over lawn or soil.

Once they do start cutting a bit of a groove, just dumping enough half-inch gravel in it to bring it back to level will fix it and you should only have to do that a few times before there's enough gravel packed in under their track to harden it permanently.

That plus some proper gate hinges with large screw plates and decently chunky hinge pins is a pretty low-cost way to make your kluged fence-gates work well enough without needing extensive re-engineering on the hinge side or extra bracing in the gates themselves, though neither of those things would hurt.
posted by flabdablet at 9:43 PM on April 8, 2019 [1 favorite]


From a physics point of view there's way less stress applied to all components if the gate is supported on both the hinge and swinging sides, as with a castor, than if the entire gate is a cantilever that needs to be supported only on the hinge side and to be internally rigid enough to prevent deformation.

Fitting castors will return the fence sections currently being used as gates to something much closer to the conditions that applied to them when they were just being part of a fence, making their existing construction closer to being fit for current purpose.
posted by flabdablet at 9:51 PM on April 8, 2019


Then they added little hinges

This a key point of the problem, too. "Little" hinges are inappropriate for such large, heavy doors. You're going to need a large hinge system more akin to this sort of setup in order for the doors to hand and operate properly.
posted by Thorzdad at 5:04 AM on April 9, 2019 [1 favorite]


You can buy gate kits that include the hinges and cross beam bits. I've got one at my house that includes a truss cable system that helps it be able to latch throughout the year...typically we need to tighten or loosen as the weather changes. This may be easier than piece-mealing the bits and pieces. Here's a kit on Amazon
but they should also be availabe at Home Depot or similar hardware/home improvement stores. Good luck!
posted by csox at 7:23 AM on April 9, 2019


Fixing the hinges and bracing the panels but not adding castor wheels won't make your gates work properly unless you also install deep-set heavy gate posts to hang the hinges off. Personally I favour prestressed concrete posts for jobs like this; it's my belief that the only structural materials that should ever go in the ground are minerals rather than vegetables. Suitable posts for an eight foot fence would be maybe six to seven inches square and sunk four feet deep, for a total post length of 12 feet. Buying and installing these would well and truly blow your $200 budget.

The existing fence posts may well do an adequate job of holding up the gates when they're closed, but as soon as you swing ten foot of heavy gate open it's no longer in line with the rest of the fence, which means you have a cantilevered load that's trying its best to pull one end of your fence out of line. Fence posts are not usually rated to deal with loads like that; they rely on help from each other and the rigidity of the fence rails to stop the fence falling over under wind and impact loads.

So the end of the fence where the gate hinges are will lean over a bit when you open the gate, and with a ten foot gate it doesn't have to lean very far at all before the free end is dragging on the ground.

Seriously, if you're not able to spend what it takes to re-engineer these things properly, just go for half-decent castor wheels and upgraded hinges.
posted by flabdablet at 9:23 AM on April 9, 2019 [1 favorite]


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