Curved corrugated roof

[ge_rik]

OK chaps - I know some of you like a challenge. Here's one.....
I've drawn all the other parts for a County Donegal van using TinkerCAD, but am really struggling to find a way to create a curved corrugated iron roof. The Irish did seem to like their corrugated iron!

corrugated van roof.jpg (334.73 KiB) Viewed 8154 times

Is it something which could be more easily achieved with Sketchup or some other 3D package do you think? Failing that I'll use my paper corrugator and attack a foil dish.

Rik

[philipy]

I've never done it ( never needed to) but here are a couple of Youtube video's of how to do it in Sketchup, that I filed away, just in case.

https://www.youtube.com/watch?v=v_bQX9I1PnU

https://www.youtube.com/watch?v=6PTPfKaWRUY

[SimonWood]

This sounds like something for which OpenSCAD is well suited! The code here is a bit crude (and could do with tidying) but it's a proof of concept. You can play with the period (or is it 'pitch') of the corrugations - and the dimensions of the roof.

Code: Select all

corrugation_radius=5;
corrugation_period=4;
roof_radius=100;
roof_thickness=2;
roof_length=150;
roof_width=100;

rotate([-0.5*acos(1-(roof_width^2/(2*roof_radius^2))),0,0])
    rotate([0,90,0])
        rotate_extrude(angle=acos(1-(roof_width^2/(2*roof_radius^2))))
            translate([-roof_radius,0,0])
                rotate([0,0,90])
                    roof_section(corrugation_radius,corrugation_period,roof_thickness);

module roof_section(corrugation_radius,corrugation_period,roof_thickness) {
for(i=[0:0.5*roof_length/corrugation_period])
    translate([2*i*corrugation_period,0,0])
        wavy_line(corrugation_radius,corrugation_period,roof_thickness);
}

module wavy_line(corrugation_radius,corrugation_period,roof_thickness) {
    translate([0,-sqrt((corrugation_radius-roof_thickness)^2-(corrugation_period/2)^2),0])
        corrugation_arc(corrugation_radius,corrugation_period,roof_thickness);
    translate([corrugation_period,sqrt((corrugation_radius)^2-(corrugation_period/2)^2),0])
        rotate([0,0,180])
            corrugation_arc(corrugation_radius,corrugation_period,roof_thickness);
}

module corrugation_arc(corrugation_radius,corrugation_period,roof_thickness) {
    difference() {
        circle(r=corrugation_radius);
        circle(r=corrugation_radius-roof_thickness);
        translate([-corrugation_radius,-2*corrugation_radius,0])
            square(size=2*corrugation_radius);
        translate([corrugation_period/2,0,0])
            square(size=corrugation_radius);
        translate([-corrugation_radius-corrugation_period/2,0,0])
            square(size=corrugation_radius);
    }
}
$fn=100;

[ge_rik]

Thanks Simon
I had a feeling this was something which would suit OpensCAD. I'll take a look at the code and see if I can understand how it works.
The next problem will be to figure out how to print it .....

Rik

[SimonWood]

I'll take a look at the code and see if I can understand how it works.

Have a fiddle with the constants at the top and see if you can get something in the dimensions you require. Let me know if you want me to explain anything and I'll do my best!

The next problem will be to figure out how to print it .....

Indeed! I wondered whether it might be simpler to make the underside smooth (as it won't be seen) but then again as it won't be seen it won't matter if the supports don't come away to cleanly!

[philipy]

The next problem will be to figure out how to print it .....

I think I'd look at sort of printing it smooth, as Simon suggested, but deepen the centre section so that it sits down inside the sidewalls by a few mm to give them some support/strengthening.

[metalmuncher]

I think I'd try printing it with a thin side on the bed, possibly with brim to help adhesion.

No supports needed as long as your adhesion is up to the task. If its a moving bed printer, orient the long edge in the Y direction so the inertia during movement doesn't try and lever it off the bed. I would think this probably nets better quality than printing it flat.

On the middle one, I've cut the edge on the bed at an angle to reduce the overhang at the top. Could make it a bit oversize then sand the angle back perpendicular to the arc once printed.

[ge_rik]

Thanks chaps
I did wonder about printing it on end, which is how I usually print my curved roofs. I usually (but not always) find that a brim works - but I hadn't thought of orientating it perpendicular to the Y axis. I usually print van roofs in two halves to help reduce the leverage towards the upper end.

I hadn't thought of flattening the base, so I'll use that as a fall-back if the vertical printing defeats my printer.

I'll tweak the variables and let you know how I get on. Thanks, Simon, for putting them at the start of the code and naming each one clearly. Makes life so much easier. Not fully understood the maths, but I do enjoy coding (eg Arduino)so will give it a try.

I'll let you know how I get on.

Rik

[ge_rik]

PS I you look at the photo, there's an extra longer arc ripple along the roof, presumably coinciding with the internal supports. I imagine another corrugating sub procedure might produce that ....... Only joking

Rik

[-steves-]

I always print my roof's on their end, they never break away from the build plate and in this scenario, the print lines would be hidden in the corrugation so that's a bonus.

[SimonWood]

I think I'd try printing it with a thin side on the bed, possibly with brim to help adhesion.

No supports needed as long as your adhesion is up to the task. If its a moving bed printer, orient the long edge in the Y direction so the inertia during movement doesn't try and lever it off the bed. I would think this probably nets better quality than printing it flat.

On the middle one, I've cut the edge on the bed at an angle to reduce the overhang at the top. Could make it a bit oversize then sand the angle back perpendicular to the arc once printed.

Really interesting insight into the art of slicing - I wouldn't have thought of these options!

PS I you look at the photo, there's an extra longer arc ripple along the roof, presumably coinciding with the internal supports. I imagine another corrugating sub procedure might produce that ....... Only joking

I think this is where I'd put the laptop away and get the heat gun out...

[ge_rik]

It's looking good so far (well on paper/screen, that is)

Luggage van w roof.jpg (141.65 KiB) Viewed 8063 times

I'll have to squidge the corrugations a bit to match the original photo - but it's a pay-off between what looks realistic with what will actually print OK. Not yet decided whether to tinker with the variables to squeeze the corrugations or just to make the roof longer and then shorten it in TinkerCAD.

Anyhow - really pleased with how it looks - so a BIG thanks to Simon for the coding

Rik

[ge_rik]

I tweaked the parameters - I think this looks better

Luggage van w roofv2.jpg (192.33 KiB) Viewed 8062 times

Rik

[philipy]

I think this looks better

Yes, looks good...but where are all the beaten up crinkles??

[Trevor Thompson]

Im looking forward to seeing this printed!

Trevor

[ge_rik]

Im looking forward to seeing this printed!

Trevor

I think this looks better

Yes, looks good...but where are all the beaten up crinkles??

Maybe I'll unintentionally get those extra crinkles when it prints .......

Rik