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1/2" OD Square Tube Coupler/connector/corner for cold frame Answered

I've picked up a fair amount of 1/2" square tube that's used in closet systems - supporting the wire shelves. 


I'm looking for some connectors so i can make some frames. the link below is a coupler for round tube, but i've got square tube pictured in the link above.


I' making some cold frames and will attach single pane glass panels, or some opaque corrugated plastic (just like cardboard,  but its semi-transparent plastic). I don't have a welder so i can't weld the frames together. I'd like to get some 3-way connectors so i can connect a vertical piece and two lateral pieces to make something like this:

or even something like this:

i also would like to have something like this swivel connector to use for the opening top window portion:

I can't seem to find any square tube couplers/connectors anywhere on the web (except for some that are in the UK) that are less than $5-$10 each.

Has anyone else had a similar need, or know of a solution?

if i made the drawings in ketchup, could someone reading this post 3-D print them for me to test/prototype???



Aluminium can be brazed quite easy with the right brazing stick, you hardware store should have a pack for around 10 bucks.
All you need is a blow torch and a stainless steel wire brush.
But there are quite a few maker spaces in the UK, maybe you can just take you file there and have it printed?


I've also got some aluminum balusters that i tried to braze, but the baluster melted and deformed before i could get the brazing rod to melt on it. are there different grades of aluminum that melt at lower temps? i thought aluminum was aluminum, not like different types of steel. it was a bummer that i couldn't get those to work. i thought about trying to put the connecting points on the gas grill, but i don't think that'll help...

I think i'm just going to make the parts in Sketchup and see if i can get someone to print them for me. it'll be trial and error to see which design works, and which shapes i need.

There are many different grades of aluminium, plus the differences between extruded aluminum, cast aluminium and cold pressed alumium vs hot pressed aluminium.
They all react differently to brazing and all are more or less sensible.
Extruded stuff like for window frames is best done with a tiny but hot pencil flame as otherwise the entire frame can melt before the brazing rod has a chance to work.
Usually I pre-heat the entire area with a bigger flame or place the part in the oven a full temp for half an hour.
The trick is to forget what you know about brazing other metals.
File the area clean right before you want to braze.
Use a stainless steel wirebrush to remove the oxide before you try to braze.
Use the brazing rod like an erazor - try to be fast enough that the rod does not melt in the flame and rub a few fast and hard strokes over the aluminium.
If it leave a mark keep rubbing, if not keep heating.
Only use the aluminium tools on alumium - do not use for anything else!!
Never use oils cleaners, just manual labour and if in doubt sodium hydroxide in water for the tough cases.
The worst you can do is to use a file that has steel dust and filings left in it or a brass wire brush - the brazing will never work...


2 years ago

can you make your own with wood?

i thought about that and i think i could. I also think the rain and weather would eventually (probably sooner rather than later) rot the wood and cause the joints to shear and drop everything to the ground one fine day when everything is perfectly set up and displayed.

Toga_Dan, I can't find any connectors of any size.

I'm not saying connectors. I'm saying square tube stock. If you buy a 10 foot piece, that makes 40 pieces 3 in long.

gotchya. That'd be good for couplers.

I'll still need to find some elbows, three-ways, 4-ways, a couple 5-ways and 6-ways.

if u can find a welder in your area, they could connectors. For that matter, fittings could b shipped to ya.

You can get 1/2" square tubing as defined by the outside diameter but usually also a size that will fit the inner dimensions.
If in doubt you can always go the long run:
Take two angle irons bars and weld them to a box of the right outside diameter, if you are lucky you might even find some in the correct size that won't require cutting the sides.
But without a welder that is impossible.
Even the right size tubing would need to be cut and welded together to form the angle.
The only other thing I could think off would be to use normal 90° angles as used for corner support in shelves.
Drill holes through the steel pipe and use nuts and bots to get them together.
For added stability you can use two angle in each corner, one on the top and one at the bottom of the inside frame.

get the next size smaller to insert in the tubing, or the next size bigger to go around the joints. Or just rod to go inside, if you don't care about rotation. Bring a tube with ya to size the connector.

haha, my iPhone autocorrected to "ketchup"... That was supposed to say Sketchup.

Thanks for the replies.

I thought about making some from wood, but I've got a lot of steel tubes and will need a lot of these things. Not to mention, these will be outside in the weather so they'll rot eventually.

As for the aluminum, I've got the torch and aluminum brazing rods, but these things are made of steel.