GRFB (Grassroots Fence Building) - Welding Tips?

My neighbor and I are replacing a shared fence between our properties. We've agreed on a double-sided horizontal picket fence that simply has a 6' picket slide down C-Channels attached to square tubing. Similar to the QuikSlip Fence kits, but taller and cheaper.

We're both DIYers who want to save money, so we've priced out parts from a local metal supplier at $600 (raw steel square tubing and c-channel), vs $1300 (complete) for the QuikSlip, and $1800 (complete) from a local fence installer/builder/supplier. 

Some methods of building the posts include rivets, bolts, self-tapping screws, and welding. 

Personally, I like the welded idea because it gives me excuse to get a small welder and practise. I'd probably also weld little plates on the top of the posts to serve as caps. 

...but I also know that what sounds easy to someone who doesn't weld is probably more complicated than I imagine. 

Any tips? Which welder from Harbor Freight? 

Is the Quickslip made of extruded aluminum?

Problem I see with steel is it's going to need a good finish after you weld it, or it's going to rust like crazy.

I love the idea of having a project worth learning to weld and giving practice time. 
 

I wouldn't do it on a fence.   It will be exposed to the elements, and buried in the dirt. Unless you have access to powder coating equipment or something equally capable of highly durable finishes, you won't be able to adequately protect it. It will rust fast. 
 

The store bought stuff will have a durable finish on it (and maybe a warranty)

Self tapping stainless steel screws would be about 10X faster. 

I'd drill the c-channel as if you were bolting it together but then plug weld it together through the holes so you don't see any welds on the outside.

You're going to need a really good finish for it to hold up outdoors.

Other people have addressed the practicality of your project. They are right. However, I'll address the issue of your question that hasn't yet been brought up.

Most HF welders are garbage. However, a couple years back at an estate sale I picked up a dual-voltage Titanium MIG 170. I figured, okay, I'll use it as a spare FCAW box or something (I already own over a dozen welding machines). 

Y'know what? That little green box punches above its weight. I used the hell out of it commercially for a bit over a year before it died, but I suspect that failure was in some part in how poorly the welder was treated and moved by some of my employees. If you don't jostle it or throw it around, it's probably a good choice.

In fact, when that one welder died I went to HF and bought another of the same model. Now, they're not without their flaws: Both of them have shown an issue where sometimes (but not always) when you release the trigger it will keep feeding wire. I'm not sure if this is in the trigger or something else, but it does mean that you'd do well to keep a set of welpers nearby to trim the excess wire occasionally.

Still, though, that green meanie works surprisingly well. It's also very lightweight, which is nice when you need to move it around. I don't know that I'd pay full asking price for it, but if you can catch it on a sale it's worth a buy. 

I think this is a great first welding project. You'll want to do something to promote drainage at the bottom of the uprights to keep them from rusting in the ground, but you could let the exposed parts grow a layer of surface rust for a specific look. You definitely want to cap off the tops, you don't want water sitting inside. 

I will add this... if you get thicker steel, your project will last longer.  My grandparents built their house in 1948, and I'm sure it wasn't long after that grandpa made a clothesline.  It was just 1-1/4 sched40 iron pipe buried in concrete with a tee and two 3' stubs of iron pipe making a T shape.  One of them rusted through and fell over about 5 years ago, but the other one is still standing.  That construction lasted 70+ years.

My dad built a similar one before I was born in an upside-down U shape, two uprights and two 90s with a pipe between.  That has been over 50 years and it still holds the tension of 6 cables on turnbuckles between it and 5 loads of wet laundry.

I might consider the cheap route.  Maybe make your posts with sched40 black pipe.  Weld your channel to it.

For learning to weld, I would try to keep the steel's thicknesses close to the same.  I wouldn't try to weld 20 gauge channel to sched40 pipe on my first try.  The real secret to welding is setting an amperage that causes the heat to penetrate the steel.  When you weld something, you should be able to turn it over and see heat discoloration on the other side that is at least as big as the weld itself on the front.  If you try to do that with two majorly different thicknesses, you run the risk of blowing holes in the thin stuff and not getting good penetration on the thick stuff unless you really have some control over where you're aiming the arc.

You're also not building an airplane or a ship, you're building something that needs to stand up to 30mph winds, so a botched weld isn't the end of the world.

You can also weld stainless just like steel, but if you don't use stainless wire, the weld and everything the weld touches won't be stainless anymore.  Be aware that stainless also expands more than mild steel, so warpage is more likely.

Brushing on a good paint will help a lot too.  Sherwin Williams, POR-15, Eastwood... all of them have good alkyd paints that will really bond well to the steel and help.  The steel safety fence around my loading dock at work was installed in 1976 and (as far as I can tell) it's been painted once and it doesn't have a speck of rust on it except where it's set in the concrete.

Note...

I'm not trying to be a wet blanket. I think a project to learn how to weld is terrific. 
 

You are trying to sell the idea by comparing prices, but you are not comparing apples to apples.  The Quickslip is extruded aluminum that is powder coated.  Your welded system won't be aluminum nor powder coated. And your $700 savings will rapidly be depleted buying welding equipment and consumables.

If you wanna build it, by all means build it. But don't compare it to the Quickslip and say it's about saving money. 
 

And be honest with yourself about the time. It really is gonna  take you 10X as much time (while you are figuring out the learning curve).  Is that OK?

In reply to Curtis73 (Forum Supporter) :

Well, SS welds *sort of* like mild steel. Not quite the whole shebang. Speeds are different and, depending on thickness, you may have to backpurge the piece so you don't get sugaring (if that's important to you). 

For this project, though, it seems like this would be welding outdoors. I'd recommend against a GMAW process here as it's going to be fiddly to dial in the shielding gas and it can be a bear for a novice to diagnose a shielding gas problem in the presence of even a slight breeze. Wire fed is fine, but I'd choose FCAW over a process that requires a shielding gas. Sure, the welds won't be as pretty and they'll have to clean up soot and slag but FCAW is also a lot more forgiving with heat and you can run it outdoors without a windbreak. 

Or, y'know, crank up the difficulty level a little bit and buy a cheapie stick welder and a bunch of 3/32" 7018. There are some surprisingly good lightweight stick welders around the $100 mark on Amazon; I own at least 2 and use one of them regularly in an industrial application. 

So, a couple things.  First, if you are not averse to the look of rust, using heavy-wall tubing and capping the top to prevent water entry will probably result in a fence that lasts "long enough."  I set an unfinished 4" dia. steel pipe in concrete to serve as the support for a homemade basketball goal and it has been standing for maybe 15 years now and looks much like it did the year after I installed it.  I don't expect to see it fall down anytime soon.  It may be worth noting that this pipe was salvaged from an industrial concern and has a wall thickness on the order of a half inch.  Yes, it was heavy.

I have since sold it, but my first welder was the cheapie H-F FCAW unit which was just over 100 bucks at the time.  It would probably be perfect for an outdoor job such as a fence.  I think I sold the unit for $50 shortly after I got the Hobart unit.

As noted above, even humble clothesline supports can last a really long time.  Slapping a good enamel on mild steel will slow down the rust.  I'd choose a color that resembles rust, just in case.    

Why weld C to square? Personally if you want to weld I would use the square but get 1.75in square tube and weld a 4" flat on either side. 

It will look cleaner and not show off your weld learning curve. 

Prime with weldable primer, paint it with Rustoleum, plug the top with plastic plugs from McMaster Carr. 

Update.

Neighbor experimented with rivets and wants to try that method. I told him he's welcome to burn up a bunch of bits for it, but I'm not keen on paying for them. 

I'm also inquiring about some rust prevention ideas. We like the idea of the rust adding to the character of the fence. We live in a low-moisture desert mountain town that likes that kind of stuff. I just dont want an 8ft custom fence falling over and not being able to replace it because the fence posts are buried in concrete within a retaining wall that makes up part of the fence. 

We're planning on writing up a contract and recording it with the deed/titles for both properties that basically states - all retaining wall issues are his responsibility, including but not limited to any repairs to the fence that require tearing apart the wall to complete. I'm perfectly fine living with his retaining wall (it matches substantially larger walls on my property that join it), I just dont want to pay to maintain it. 

In reply to pheller :

Yee gads!  Rivets?

Get yourself a welder and challenge him to a race to see which method is faster! 

Good enough to hold a car together and wont initiate rust.

I'm afraid rivets aren't likely going to last long, especially in steel.  They will corrode quickly.

The mailbox post I'm building from 4x4 square tube is going to be unfinished so it rusts.  I cut out "leaves" and used a grinder to make vines in it.  I plan on sandblasting, filling the vine grooves with paint, and letting it rust.

There are those who've long suspected it, but this is proof positive.  Curtis, you're a....   you're an.....   Artist!!

I know I'm coming at this from a simpleton farm kid standpoint, because that's where I got this experience, but setting a steel pipe in concrete and then welding hinge hardware to it resulted in fence corners that lasted for decades.  No paint.  Plug in the top to keep water out where newspaper was wadded up into a ball and pushed about 6" down from the top and then concrete poured on top for a cap.  The wall thickness was always pretty thick.

I like the idea of using c-channel that has holes drilled in the face that butts against the post and then welding there to hide the welds.  What about using something like Rust Bullet sprayed or rolled over the welded post assembly?  Would want to make sure the steel was clean and maybe some quick passes with a sander before paint.  And then an oil base paint in a desired color on top.    

Something like the tar "Post Saver" sleeves meant for wooden posts but used at the point where the post meets the ground, where wooden posts like to rot off, would that be useful in keeping the rust from starting so soon?

1988RedT2 said:

There are those who've long suspected it, but this is proof positive.  Curtis, you're a....   you're an.....   Artist!!

I'm not a real artist, but I did stay at a Holiday Inn Express last night.

In reply to pres589 (djronnebaum) :

Post savers might be wise.  I'm also told that one of the perks of using the expanding 2-part foam to set posts is that it's closed-cell foam and keeps water away from the post.

In reply to Curtis73 (Forum Supporter) :

What 2-part foam do you speak of?

In reply to pres589 (djronnebaum) :

I would guess he is referring to this Sika product. 

Sika 2 lb. PostFix Fence Post Mix, Mix-In-The-Bag Expanding Foam for Supporting Non-Structural Posts, Mailbox, Sign 7116170 - The Home Depot

You might look into weathering steels, ASTM A606-4, A588, and A847 finish. 

They are self-protecting and don't need a finish. They are using it for K rails and power polls around here. It weathers to a burnt orange or brown color.