Thread: Bending Flat Stock To Form Polygon Then Weld

When designing these types of shapes, I make my angles either 120 or 60 never 90 degrees....that way you can insert 60 degree triangles neatly within your shape. Giving you the triangle structural support that you need. It also means that you can then use pieces of steel of various lengths bent at 60 degrees to weld your shape together.

Originally Posted by BobL

In your latest design the roof will push the walls out.
Structures are usually stronger, especially in corners, if the forces push the building together.

This is one way of doing it, also it's very simple.

Really only an issue while assembling the portal frame, many portals are assembled using that mitre type joint.
On that subject, do not paint the faces of the mounting plates that will mate together, you actually want rust to occur at this interface as it increases the joint strength.
For ease of construction, I would construct a column with a 90 degree top plate angle and bolt your truss between the columns. Your fascia purlin and girts are then all mounted off the column.
The flat bar polygon connection design would best be committed to the round file in my opinion.
By the way, a 30 degree pitch as the original design suggests is damn steep, you may want to have a look at that.

That is a new idea to me Bob, but then as I said I am not an engineer. My shed is built to your design but there are joints like Meadow Streets designs on sheds at work. These are made from about 600mm I beam tho. I remember the design because it is in a section that has a higher centre section and can be seen easily from the next section which is full height and width all the way up. Very obvious construction.

Drawing1.jpg

All done with only I beams as per the drawing design from Meadow Street. The centre section would be about 12m, similar to MSs span.

Now back to the reality of 48mm black pipe. Its all a learning process.

Dean

this is part of my respose:

Hoping to get the planning and inspection people on side with the heritage ticket. Recycle reuse and repurpose being another. might work?

Nundle is a gold mining town and many of the original building have high pitches, some to 45 degrees or more and I would like to go with 30 degrees if possible. maximum solar gain here is 30.0263 degrees or something. great for solar on the north side !

getting the aged hardwood loading dock, verandah posts and exterior visible gable supports through might also test this theory, but we'll see.

a supportive struct engineer is a must.

thanks Rob for your warning of new standards for old designs.

thanks for encouragement bob ward and bobl I will consider your tweak on the plate angles.


I was very happy when I stumbled across 30 degree pitch GTVI.

Took me a while to realise that I didn't have to set my drop,saw at 60 degrees (impossible) but rather at 30 degrees off 90.


Karl robbers, thanks for the no paint tip ! I had that written in the journal from another reading/researching jaunt i had a while back.......in fact a boiler maker from Newcastle reinforced that one too when he dropped into my shop.


love you to explain this though -


"For ease of construction, I would construct a column with a 90 degree top plate angle and bolt your truss between the columns. Your fascia purlin and girts are then all mounted off the columns"

can't quite picture it, but sounds good.


I,ve got about 100 pieces of the pipe in question.....eight per bay for the truss and column chords over seven or eight bays = 64 accounted for.


36 to bend up some heritage looking driveway double gates and a single entry gate and another entry gate.........leaving a few for ????.?.


and we are only of the knee joint ........with apex joint and haunches, base plate connections, diagonal bracing and plenty of other things to consider !


thanks for the diagrams and pictures too guys makes it very interesting!,,

this is where the building will sit

In South Australia roofing trusses didn't have to be inspected after erection, but under new law changes they now do.

The standards/rules are always being changed and it's ridiculous to think you can pull down a shed with old specification purlins and beams, and not be able to put it up again under the new regs.

Council inspectors are not very flexible from my observations, and they will refuse to approve plans with a one inch difference from the current standards.

Rob

Originally Posted by meadow street

this is where the building will sit

Very nice. Lovely backdrop in the distance. I have a lovely location as well but it is all flat around here. Your location is a bit too close to the road for my liking tho. We are about 100m away and shielded by bushy wattle trees etc. Heaven. Are you going to have access to 3 ph power? Not available for me.

Dean

just dug the hole for the 3ph power pole to go in Dean.....lucky in that department so far (fingers crossed).

we'll test'em out Rob.

there's always colour bond and pre engineered flatpacks to fall back on: )

F know's what I'll do with all the rods (pipes)....we'll see.

more sketching for me to do now.

regards

Originally Posted by meadow street

Karl robbers, thanks for the no paint tip ! I had that written in the journal from another reading/researching jaunt i had a while back.......in fact a boiler maker from Newcastle reinforced that one too when he dropped into my shop.


love you to explain this though -


"For ease of construction, I would construct a column with a 90 degree top plate angle and bolt your truss between the columns. Your fascia purlin and girts are then all mounted off the columns"

I was assuming, perhaps incorrectly, that you were using steel columns.
What I was suggesting was to have the column/truss interface in a vertical plane, with the truss fitting between the columns. This means that your purlins, with the exception of the fascia purlin are all mounted on the truss top chord and your girts, assuming an enclosed shed, mount on the columns, with the fascia purlin, (this has both the roofing and the wall sheets fastened to it).
You could place the truss on top of the post, but this method requires some mechanism to prevent the truss wanting to flex side to side.
At a 30 degree pitch, you may need to cut the top of the post at an angle to gain the required clearances, the more typical lower roof pitches usually don't require this. I would also recommend some horizontal tension bracing in the gable, due to the fact that any deflection will cause quite a length increase in a gable truss @30 degrees, far more than a lower pitched roof.
How are you going to assemble your portals? IE can you bolt the truss and columns together and erect them as a unit? Or will you need to erect and plumb the two posts and then assemble the truss between them? Both have advantages and disadvantages.
Don't over weld your trusses either. Too much weld will cause more trouble than it solves and make sure you tack all the web in before you start to weld off the truss. Stagger the joins in your top and bottom chords to prevent potential failure points.

you are reinforcing many of my other ideas, thanks!

i drew this sketch before you explained it again......pretty close?

cheers mate

If the design has to be engineer approved, then probably you will have to go with what she/he says...

Hell I am surprised in this day and age the person doing the welding does not have to be approved as well... And the steel it is made from certified.. And as well the person building it has to be trade ticketed..

And you have to do a full environment impact study, a carbon emissions study donate $50 000 to the local council so they can give themselves a pay rise sign off on all your plans and studies and make sure no one within 500km is offended by your new shed...

Here it is a bit simpler... Anything 200m or more off the road used primarily for primary production is exempt from all the regulations...

In the real world does not matter what you do here, being so far away from the powers that be, they leave us alone...

Yep, that's the one. I tend to turn the connector plates 90 degrees, (so the bolt holes run along the truss, rather than across like you show, but that's no biggie). I would usually tend to mount my facia purlin (eaves) off the column rather than the truss, again no biggie. Yous seem to prefer quite an overhang on your eaves in your sketches. Is that to fit in with the general style of the area?

The other thing to consider is don't build your shed under/too close to an ETSA power line.

They are very strict about access issues in SA.

My Bro in law put a car port/open extension on the side of one of his sheds and ETSA made hime take it down as it was too close to an overhead power line.

Lots of rules/regs/snags these days.

Rob