Welding a steel driveway gate pt. 1

Old pipe with a new purpose

Our humble homestead has rather a plain driveway. Nothing but sand and weeds near the end of a dirt road that's compact as concrete in the summer and turns to mush in the spring frost heave. At least one of those things is going to change this year- the boring part. I've had some surplus steel sprinkler pipe in the rack for years now, telling myself every summer I'd get around to building something cool with the 4" pipe. Well enough of the somedays, now's the time to get it done. I completed much of the posts and side-rails before remembering I should take more pictures, but I'll be better at documenting the electric opener build.

Starting with the posts

So here's most of what I'm working with: a pile of sprinkler pipe I picked up cheap at an auction. Not much to look at here but let's see what happens when the magic of welding is applied.
pile of pipe

The main 4" posts were prepared by welding 4' short chunks to the two 8' pipes, as they weren't long enough to get buried below frost level on their own. Then I flame cut some holes in the side, so concrete would flow inside the pipes as I poured it in the hole. I finished those by spraying with cold-galvanizing compound; basically a zinc-rich primer, then topping that off with some leftover paint cans. The nature of the mill-scale on what was formerly a water pipe would probably survive just fine, but we're already well into overkill range on this project so why not go all the way?

The site of the pipes was measured out and marked with marking paint. I had that 16' between pipes and drove the truck and trailer over the marks for a few days and decided for the sharp turn into the driveway an extra couple feet would be nice. So with 18' marks in place I started some post holes. The county says frost line here is 30 inches, so I over dug to about 36 and filled up to 30 with pea gravel on the one side. I ended up going to nearly 44 inches deep on the uphill post. It doesn't look like it but there's about 9" of drop between the posts. It doesn't look like it on the camera and it doesn't look like it even when you're standing there. When I was measuring with a string level for the rails I could not believe what the level was telling me. It's not just that step up in grade next to the driveway, the whole property has a slope to it that's deceptively steep when you're estimating for level.

One of the reasons I forgot to take pictures is I was focused on my first every concrete pour and trying not to screw it up before it hardened. Turns out I was overthinking it again and everything went very smooth. While just filling the hole to grade with concrete and calling it a day would have been functionally fine, but I wanted a bit of a pad around it both for looks and a place to bolt gate-opener enclosures in the future. The form was built with some plywood scraps about 3.5" tall and set half way into the dirt. They were nailed together and dirt was tamped around to hold them in place for the pour. Then the sides were given a generous coat of vegetable oil as a release agent. I wasn't to sure about how well that would work but it's what I had. Guess I'll see in a few hours.

The pour

Another cheap auction find was a 2-bag cement mixer, which sure saved a lot of back-breaking work on this job. The deeper post took 4 whole bags to fill (including inside the pipe) while the other took just over 3. First two bags were a bit on the dry side and didn't want to flow into the hole well, so it got extra tamping to get the air out. Should have made those bigger. Second post I mixed quite a bit wetter, and also remembered to moisten the sides of the hole with the hose, as this sandy soil can suck the moisture right out of concrete and dry it out too fast.

I got too into the project details to remember the camera for this next part. I placed the two heavy steel sawhorses on either side of the post, then clamped 2x4s perpendicular to that while nudging the post to level in it's gravel base. That felt like it held things very securely so nothing can move when the concrete is poured in. Just for good measure though I kept rechecking this little gadget:
a post level
It's a cheap post level, nothing you can't do with a regular spirit level but it is quick and handy as your tamping things in to place. It takes a string or a big rubber band to hold it on a wood post but there are magnets in this one that hold it well enough on these round steel posts.

Some mixing, wheel-barrowing, tamping, troweling and about 6 hours later I dared to see if the forms would come off. Well what do you know, they slipped right off the sides in one piece like it was all teflon. For a quick form release vegetable oil works great for small projects.

first ever concrete pour

The supports were left on the posts overnight. I set the big steel sawhorses on either side of the post and clamped boards on to hold them upright. I thought this gadget was perhaps a little gimmicky when I bought it but it turns out a post-level is darn handy especially with the built-in magnets. Helped me set the posts straight and made sure they stayed that way while everything firmed up.

The railings, and some design considerations

I'll spare you the details of the outer 2" posts because I didn't get as fancy there- just pour the concrete in the hole to grade and call it a day. Finally I could get to the fun part, the welding.
first section
These horizontal pipes are only .040" wall tubing so I had to be careful with the welder not to blow holes in them all over. I cut a pair of 2x6s with v-notches on each end to act as spacers and keep each rail exactly the same height above the other. The bottom rail was held up with a floor jack, as that let me play with the height of the ends and see what looked best. This took a bit of playing with. I was just going to keep everything level and just move the south rails up a bit over the little dirt plateau on that side of the path, but it still looked... strange. This isn't yet becoming a whole pipe property-fence but I suppose if it was that, of course, has to follow the curve of the hill up and down large and long slopes. After playing a bit I found about 2 inches of drop made all the difference, and the pipe rails looked to better 'follow' the slope of the hill. So now the other side of the driveway:
second section
Much tacking and welding later, and here is a classy looking driveway entrance if I do say so. Time to stand back and admire the results.
rails complete


Update

Part II is up, and available here: Custom driveway gate part two