Curved sheetmetal roof- Pattern development.

[bletchmonster]

Hello All. To avoid wasting endless hours and a lot of sheet, I was a wundering if there is a method of developing a flat pattern when joining curved sheets at the mitered joint on roof hips . I attach the pic as an example. That curved corner joint makes my 2d brain hurt trying to how to lay it out.
I can do truncated cones , pipe saddle joints etc by the paper and pencil method (I lie a little, I'd have to relearn some of it)
But I don't even know what to call this type of joint so not having any joy searching for the method. Could anyone point me in the right direction?
I have a customer wanting this style of roof made from sheet steel on a canopy and where as I think I've sussed how to make the rest of it work, that joint eludes me ( doesn't take much I know)
I've done well to avoid this type of joint this long, I must have dodged a few fireplace canopies in my time!

Any suggestions appreicated, even if its just where to look to educate meself!
Cheers, Ed.

 

[Maker]

You could do a parallel line development just like you do with a pipe saddle.

 

[gaz1]

follow the copper sheet folding method

 

[bletchmonster]

Cheers for that Gaz, very useful video, but it looks like he's got flat ends on the canopy, where as I'm looking to intersect two curved panels, hence the smoke from my ears!

 

[gaz1]

you do it out of 2 pieces so that they can overlap to the edges its really the same method as the video

copper shingles is more interesting

 

[gaz1]

this one will point you in the right direction for you

 

[bletchmonster]

You could do a parallel line development just like you do with a pipe saddle.

Your probably right, I need to sit down with my pencil and paper see if I can make it work. I can't take a template off fresh air so I need to develop some sort of pattern. I can see me just building the thing and taking it a stage at a time, I'd just like to use a proper method that would give me a shape/pattern before I start.

 

[gaz1]

you can make pre standing panels easily enough but most of the time its on the job when fitting where most of the work is done

or you have to build a former to create the shape needed then you start to shape to the former as if your actually on the job itself

it all depends on the length and also how big the roof is determines what pieces you do and the shape your going to create

jigsawed mdf comes in handy for creating the preshape with plyboard face it also gives the customer the chance to see the shape or make any changes to it

look up copper shingles on a domed roof looks way better than the flat sheet

 

[Morrisman]

CAD. Cardboard Aided Design. Make a scale model 1" to 1'.

 

[Agroshield]

The scale model is a good idea. Maybe glue some foam together and make a 3D model. You can then cut the curve out of two sides, lay a sheet of paper onto the buck and trace the corner.

The pagoda roof you show looks to have non-circular (maybe parabolic) curves. It would be easier to start with a circular arc for one of the two sides.

Look up 'curved hip rafter'.

You will find these, which might help:

Curved Hip Rafters

A blog about roof framing geometry.

sbebuilders.blogspot.com

Curved Or Molded Roofs

Fig. 91. - Conical Tower Roof with Rafters Concave in Form. Fig. 92. - A Convex Mansard Roof. Fig. 93. - An Ogee Veranda Roof. Having presented to the reader a practical system for almost eve...

chestofbooks.com

https://archive.org/details/hicksbuildersgui00hickiala (I think this is the one referred to in the link above)

 

[bletchmonster]

Thanks Fellas

 

[Agroshield]

You could do a parallel line development just like you do with a pipe saddle.

I thought about your reply today and you are more correct than you maybe realise. If you change your viewpoint a little and instead of looking at the roof itself, look at the air surrounding it, that exactly represents the intersection of two pipes.

If you had a block of ice and two pipes saddled at 90 degrees with hot water running through them and laid the pipes on top of the ice block, the shape they would make once they melted their way in/down would be identical to the roof.

 

[bletchmonster]

I Thanks again. I'll spend some time playing around with this. The job is going to be post Christmas so I've got plenty of time to work though these ideas and probably play with some cornflake boxes. I'm trying to get a rough idea together before meeting with customer and architects end of this month. My standard procedure is to take these jobs on with no idea how I'm going to achieve them.
Always works out. but is not relaxing in the meantime. Dammed architects produce reams of cad drawings with no idea of what's involved in turning them into reality.