Gate frame

Hi Group,

Before I get started, this is my first metalworking project.

I'm going to build a gate frame, then clad it with corrugated steel roofing in the same colour as my roof, so the frame won't need to support timber or other heavy cladding.

The design will be a rectangle, length of 2.5 meters, height of 1.5 meters, with a brace running from the bottom of the hinged side, to the top of the swinging side. When closed, the gate will rest on a little foot, to alleviate sagging issues.

What type of material should I be using? I was thinking box tube of

20x20mm, or 50x20 if required. As a beginner welder (arc), I guess I don't want a thin wall. Is my suggestion overkill or not enough? What wall thickness should I be looking at?

Any help would be greatly appreciated.

Roger

Reply to
Default
Loading thread data ...

Hi Roger, I made a gate just like that but 3m wide about 22 years ago. It still functions fine. I used 50x25x2.5mm gal RHS for the frame. The frame was painted as well.

20x20mm is way too small IMO, for the weigth of this gate.

You also need a good hinge system, I used a 8mm pin that fits top and bottom into the horizontal frame, close to the edge. This really should have had a reinforcing tube or a block inside as the pin hole wears away over time. Otherwise, this type of hinge is perhaps the strongest simple method of hanging the gate.

Weld the rectangular frame first and then mark and cut the diagonal brace. If you cut it first it might not fit as I found the hard way. Things move a little when welding them together.

Klaus

Reply to
az_100

Why the brace the wrong way?

Steel :-)

20*20 is ridiculous. I would use a 40 * 40. A 50 * 20 would be OK for vertical load (if the profile is standing), but it will just warp and wiggle in the plane.

Yes. Then practice.

1.5mm, maximum 2mm

Nick

Reply to
Nick Müller

Exactly. The way you have it described, the diagonal member will be in compression, and thus likely to buckle under load. And

*don't* bet that nobody would ever try riding the end of the gate. Someone *will* do that.

Running from the top at the hinge end to the bottom at the free end will put the diagonal member in tension, which will make it stronger.

Aside from that -- I'll let the others comment on the size of the material, as I have not made anything of that size.

Good Luck, DoN.

Reply to
DoN. Nichols

Interesting, I was under the impression that a brace employing compression was more effectinve than tension.

Just as well I asked :D

Roger.

Reply to
Roger

Great. That's what I wanted to know.

Can you please elaborate? I can't visualise what you're describing.

Phew, that saved me some time. My original plan had me cutting everything at the start.

Thanks for the detailed response Klaus

Roger

Reply to
Roger

:-P

Considering the gate when closed will be suppoprted top and bottom on both sides when closed, there should be no wiggle.

Looking at Kalus' post which says 2.5mm, and your 2mm maximum, was there a reason for that?

Roger

Reply to
Roger

But only if you intend to make it from concrete. :-)

No, always try to make expand them, not compress. If it is compressed, it will swing to the side. Euler made a formula (don't know how you call it in the US) that shows how little long, slim parts can take if compressed. It is _veery_ little. Imagine using a rope/chain.

Nick

Reply to
Nick Müller

But while you close it. It should be stable in all conditions. Also, it will look very lousy. Really, you won't get happy with a 20*50. The absolute minimum would be a 30*30*2 + a 8mm (or so) brace.

Yea, well. If you have the brace, you don't need that much stiffness (to prevent sag). Also, it is a good training for your welding skills with

1.5mm :-) I think it's unnecessary to have 2.5mm. But if you want, go for it. It will just weight more and cost a bit more. And is easier to weld.

Oh! As this is your first welding project, some tips: First cut _all_ parts (excluding brace) and lay them out. Use C-clamps to fix. Tack weld in the middle of the seam. If you have someone to lend you a hand, flipp over and tack the other side. If you are alone, don't flipp the frame over, or it will fall apart (well it can be done alone, but only if you know how and have the right welding bench). Watch to weld "center-center". That means, do not weld in one go, but start in the center and weld outwards, then from the center inwards. If not, you will get out of the right angle. Finish one side (frame laying flat). Let cool down, check the right angle and weld on the other side to correct. If you have less than 90 degree, weld from the inner side to the outer. If you have experience, you can correct any errors by changing the sequence and welding "in-out" or "out-in" etc. Also, you don't need to let cool down. A "bit" tricky!

A OA-torch can be quite handy for corrections. But this is another lesson to learn. :-)

While I am at correcting: Meassure the diagonals. Where the longer diagonal is, put your brace in. You can correct a few mm with it. Only then weld the hinges. Because now you know where left/right and top/bottom is.

For the hinges: We have here (in Germany) _very_ nice and _very_ cheap and _very_ good weld-on hinges. I would use at least 120mm hinges. Go look for them. It is not worth at all making your own ones.

HTH, enjoy!

Nick

Reply to
Nick Müller

I have made many gates, once having been a steel erection contractor for nine years, making ornamental metal.

I believe all things steel should be made to support three times what they need to support. A gate of this size made of the proper materials will easily support the 3x weight. But that doesn't allow for the fat little brat that will try to ride on it.

Hence, the "banjo string" tensioner. A solid diagonal brace that is solid running from the top of the post side of the gate to the bottom of the swinging side of the gate is okay, but it does not allow for tensioning. AND, a diagonal going the other wrong direction does not allow for retensioning if it every becomes tweaked for any reason. It must be removed and replaced, which may involve a lot of cutting and blasting.

A simple aircraft cable or single rod/allthread tensioning system allows for lifetime adjustment of the gate. Posts settle. Earth moves. People hit the gate. Fat little kids ride on it. Fat 32 year old kids ride on it.

One of the surprising things about gates of this type is their flexibility. I used to have to straighten a lot of gates. A remarkable amount of straightening can be done by laying the gate on bricks on the ground and jumping on it. A remarkable amount of straightening can be done with a come-along on the diagonal. Use soft nylon slings to hook on to the steel so you don't cause more bends. You think they are solid, and they are heavy, and they feel solid. But they tweak really easily.

This person is talking about putting backing on the gate. If this is done, AND A NUMEROUS AMOUNT of screws are placed to hold on the backing, this adds a LOT of rigidity to the piece. Just, please, use a measuring tape and put them on at even spacing! I get so riled when I see a good looking gate with backing that looks like a drunk monkey put in the screws. It isn't hard to follow a tape to evenly space the screws, and it adds LOTS to the final appearance. So does good cutting of the backing pieces, particularly around locks and latches. Looks like a real pro did it. A person who knows ZERO about gates can see the difference between even screws and ones put on helter skelter. However, the banjo string will make the backing deform if it has to be tensioned a lot. In that case, the screws may have to be removed until the backing lays flat again. But, if that happens, there may be enough damage to just replace the backing.

Just some observations from messing with that stuff longer than I care to remember.

Banjo string tensioners are cheap and work really well.

Steve

Reply to
SteveB

Reply to
RoyJ

[ ... ]

O.K. I can accept that. But he was talking about building a steel gate, not a wooden one.

Enjoy, DoN.

Reply to
DoN. Nichols

Roger, re the hinge system I mentioned. You will find that most fridge doors are hinged similarily.

Regarding the diagonal brace, I read the responses with interest. My gate has the brace in compression, I carried that idea over from a wooden gate I also made. The steel gate frame never sagged yet with the diagonal in compression. This gate also survived my 2.3 ton 4WD rolling into it (hand brake failure), knocking the gate off its hinges. The frame held its shape, the 50x25RHS is on edge ( narrow side up) BTW. The thickness was chosen for ease of welding, it is VERY easy to blow an unsightly hole into thin wall RHS with a stick welder and a mediocre operator :-0. The colourbond steel cladding was pop rivetted on, some of the rivets have been replaced in the 22 years since this gate was first hung. Klaus

Reply to
az_100

Ahhh, and as my experience lies in wood, that's where my assumption of compression over tension came from.

Thanks fella's.

Roger

Reply to
Roger

Wow, thanks for all the info Nick. There are a lot of great tips in that post.

Roger.

Reply to
Roger

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.