Heavy gate strategy

[Ken Albert]

Finally getting around to building a driveway gate. Two halves, opens from the middle, about 7.5 ft. each half, average 1.5 x .25 inch stock, so fairly heavy, riveted primarily, attached to 2 large granite boulders, top hinge attached to rock, bottom hinge in ground, maybe drilled block with ball bearing, pin riding on bearing.
The thing is, I know there must be a bunch I'm not taking into consideration. First time around there always is, so the ideal help would be a picture of the structural parts of gates with a discussion of structural strategies/tips and of hinge strategies in particular. Maybe there is a link or a book that would help me do the thing without having to take it apart next year to make it right. Or some of you who have this kind of experience could chime in. Thanks for your help.

[Bruce Macmillan]

This one is a biggie..........Copied from Francis Whitaker's "The Blacksmiths Cook Book".....A sketch of what you are trying to accomplish would help.

[Ken Albert]

Finally getting around to building a driveway gate. Two halves, opens from the middle, about 7.5 ft. each half, average 1.5 x .25 inch stock, so fairly heavy, riveted primarily, attached to 2 large granite boulders, top hinge attached to rock, bottom hinge in ground, maybe drilled block with ball bearing, pin riding on bearing.
The thing is, I know there must be a bunch I'm not taking into consideration. First time around there always is, so the ideal help would be a picture of the structural parts of gates with a discussion of structural strategies/tips and of hinge strategies in particular. Maybe there is a link or a book that would help me do the thing without having to take it apart next year to make it right. Or some of you who have this kind of experience could chime in. Thanks for your help.

I respect few people more than Groucho. Thank you, Bruce for your help. The gate will be 3.5 feet high with primarily a grid design, so few major triangle elements to hold the square. I plan to weld strategically to help retain shape without making too fabbed a look. There will be a flat stock member across the top to make it basically like an angle iron component with the same treatment vertically where the two gate panels come together. The outside verticals, where the hinge attaches will be something like 1.5 inch round stock drawn smaller for most of its length, maybe .75 x 1.5 square and upset a little larger before it forms the pin to enter the bottom block/hinge. With a skeleton footing at the base of both rocks and a sufficiently skookum upper hinge, I'm thinking the sag might not be too bad. It might be good to have some kind of adjustable feature in the top or bottom hinge, but I'm not sure what kind of design that would be. To remove much torque might be more than is reasonable for a 3.5 x 7.5 foot grid.

[Tom Allyn]

..... bottom hinge in ground....

Where is the installation? If it's here in the Great NorthWet then you might be concerned with water pooling in the bottom hinge and rusting it out.

To remove future sag you might consider mounting the top hinge over a shim plate that could be removed or replaced with a thinner plate in the future.

[JNewman]

The book "Forged Architectural Metalwork" by Peter Parkinson has a chapter on gates. It has lots of good information on gate design as well as lots of pictures of gates showing how other smiths solved the stiffening up of gates.

[Bruce Macmillan]

Sounds like they'll be pretty stout.......just don't factor out the sag factor, 7.5 ft of overhang can't be denied. I'd build in an adjustment on the posts at least.

[Ken Albert]

Thanks to you all for the input. I live in Olympia, so rust is always a problem. For the bottom hinge I was looking at a block hinge that has a zirk fitting. It would not actually be in the ground, rather embedded in concrete. Of course, water would be impossible to keep out, if it were kept greased, it should survive a while. I guess the alternative would be putting the pin in the concrete and the socket and bearing in the gate member.
I will look at the Parkinson information, English smith I think? There has to be significant sag over that length, can't get around it. The shim is a good solution I had been considering, but the thing I'm still puzzling is the details of that upper hinge attachment. The only thing ocurring to me is a wedge/expanding bolt that is not bottomed out at initial installation and can be driven further to take up sag. I guess it wouldn't have to drive far to take up a lot of sag over 7.5 feet.
Maybe an improvement would be to pin a weld plate solidly with epoxy over a shim, replace with thnner shim and shim under the bolt head to take up slack. A threaded rod through the weld plate would make dialing in the adjustment easier, but a person might notice that he could spin a couple of nuts and walk away with a new gate.

[Bruce Macmillan]

a person might notice that he could spin a couple of nuts and walk away with a new gate.

Don't be messin' with Sasquatch!!!...You can always make another.

[Tom Allyn]

I guess the alternative would be putting the pin in the concrete and the socket and bearing in the gate member.

Good idea.

[John Bellamy]

If you are considering welding at strategic points, then sag should not be a problem.

The1/8" per foot allowance was used for traditionally made heel bars and tenons rivetted together, these would 'sag/settle' after installation

The stock sizes you are anticipating using are not comparable with the sizes of and weight of the traditional gates, typically, 2"+ square back stile, infill bars of 3/4" square, Dogbars 1/2" square, scrollwork 1/2" x 3/4", cross members 2 1/4" wide x 1/2 thick, Slam bars, inner stiles of similar proportions gates weighing over a ton each being a common size, Gates 6 feet plus high, hardly comparable with the modern concept of contemporary gates.

As to hanging the gates, It was common practice to extend the upper journals mounting to be extended and incorporated into the pillars and walls built at each side of the driveway.

It is essential that the supporting structures are solid enough not to move as the gates are operated, I have seen pillars crack and lean at the base as supporting walls have been rebuilt and the old extended internal strappings for the top journals removed.

The Hanging arrangement was a journal on the back stile towards the top of the stile, and at the base the back stile was forged round between swages and the end forge semi spherical to give a ball ended pin (Probably 1.5" diameter on a 2" square backstile) that then located into a cast/forged iron block that can be secured into the foundations that has a suitable clearance hole (1/16"+ on diameter) for the base of the back stile to fit into. The top of this block being above ground level the socket being well greased at installation.

These will stand and work for many years before any adjustment should be needed, it was common practice to set the gates so the centre opening was not parallel, a narrower gap at the base than the gap at the top, this discrepency was disguised by the slam bar, and allowed for a certain amount of wear on the top journals over the years.

If the gates are used regularly, there should not be too much of a problem with water ingress and rusting, sand and grit are more of a problem.

I hope thai has een of some use, and if you have any specific problems with it, please feel free to ask for clarification.

Good luck and success in the project.