how to build a curved wall?

[Albert Lee]

I am in the middle of my next project, am trying to build a pumpkin cart bed for my daughter.

I have completed so far, and now I am stuck.

HOW DO YOU BUILD A CURVED WALL???

I need to build 3-4 of these walls so I need them to be repeatable.

the sphere is 6ft/1800mm in diameter, 5ft(1500mm) high. there 8 posts/8 sections.

thoughts and comment please.

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[Bill Dufour]

Fiberglass, flame resistant cloth, wicker, leather. metal screen. panel beater could make something for you. lath and plaster
Bil lD.

[Albert Lee]

Fiberglass, flame resistant cloth, wicker, leather. metal screen. panel beater could make something for you. lath and plaster
Bil lD.


I was hoping to make it out of timber... maybe this will take too long... perhaps fibreglass will be the most viable option.

[Carroll Courtney]

Maybe out of slats? Say take few 1/8 pieces and a bending form to shape you need and glue them together. I did this when I made my daughter a rocker but I glue contrasting wood together.

[Patrick Walsh]

If you want it to be wood then “ribs” then wacky wood.

Google both and you will figure it out.

If plaster kinda the same then 1/4 rock as far as it will bend. May have to break it and seam as it wants to crack. Seam it then continue on. You will make octagon pretty much then build up mud/plaster to make a perfect radius. You can also try scoring the back side of thicker rock and bending that but I’d probably just go with layers of thiner rock.

If wood your gonna have exposed fasteners. Using laminate or veneer over you work after it’s built can mitigate this. Otherwise you can try and secure it from behind or use some kind of puck and or decorative washer/fasteners from the front almost as a design element. Watch the news you will see panels made up like this with pucks all over the place.




Maybe out of slats? Say take few 1/8 pieces and a bending form to shape you need and glue them together. I did this when I made my daughter a rocker but I glue contrasting wood together.

[Bradley Gray]

Made a bunch of trees for a museum using Structolite plaster:

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[Bill Dufour]

Shingles?
Bill D

[Jim Becker]

I would do it with wood slats, either flat or bent, tenoned/Domino-ed between the ribs, and not try to make the walls solid. Having air space will help insure it doesn't get hot in the gourd, as it were, while still giving the visual look of a solid object. THAT is a very kewel project!

[Stan Calow]

Bendable plywood? Not sure how thick it comes.

[Jamie Buxton]

I don't understand what you're trying to do. Maybe you're trying to hang a spherical surface on those ribs? If so, inflate a weather balloon inside that structure. Cover with fiberglass and resin. Wait for it to cure. Deflate the balloon and remove.

[John TenEyck]

Make more ribs like you have except taper them so they fit together like barrel staves.

John

[Bill Dufour]

expanded metal mesh

[glenn bradley]

Bendy-ply. (https://www.columbiaforestproducts.com/product/columbia-radius-bending-plywood/)

[Jim Becker]

I don't understand what you're trying to do. Maybe you're trying to hang a spherical surface on those ribs? If so, inflate a weather balloon inside that structure. Cover with fiberglass and resin. Wait for it to cure. Deflate the balloon and remove.
That would certainly be one way to make a pumpkin, but the OP stated he wants the end result to be wood.

[Kevin McCluney]

Having done numerous projects on my and my friends houses I think curved walls are the norm...:D

[Don Stephan]

When I needed to make a bent plywood item years ago I purchased 1/8" thick poplar bending pywood from DSI, a commercial supplier. Bending (wacky) plywood did not always bend smoothly.

[johnny means]

Your a little deep in the process to be exploring such an important detail. I would build a form from stacked insulation foam and cover in a couple of layers of resin impregnated fleece. The fleece stretches easily to conform to complex curves and is fairly cheap. Provided all the sections are identical, I would do a flange on one side of each panel and do a ship lap type joint all the way around. Another option is a simple skin on each facet, followed by thick upholstery I've taken on similar jobs and can tell you this is not a job for the faint hearted. I wouldn't even begin to think about doing this in wood, if I couldn't dedicate six months to it and was paid accordingly. I must have been asked to copy this bed 50 times over the years, and really wanted to do it. I never could make the math work out without approaching six figures

[william walton]

Bending plywood is pretty easily available and comes 3/8" typically. Sometimes called wacky wood. Both barrel and column forms.

[Tom Bender]

Albert
Did you steam bend those ribs or lam bend them? Nice work either way.

Now you want boatbuilding skills.

[Charles Lent]

If it has to be wood, make it like a barrel, with staves, thin wood steam bent and then joined together and held with glue and reinforced with banding. The more staves in the barrel, the rounder the barrel will be. Determine the stave dimensions based on segments of the diameters at several levels and make a flexible template, then cut many staves to the template shape and steam bend them on a curved form. You are dividing up a circle into multi degree segments, and the width of each segment at any point will be a segment of that diameter, ie. a 36' circumference divided into 36 segments (staves) will be equal in width to 1/36 of the circumference or 10 degrees to = 10". You will need to determine the stave width at many points this way.

I built a 6' ball one time (a giant baseball), and a pumpkin is a ball, but with decorative pieces attached. This is a very time consuming project. I spent almost a month full time on that ball. Then the decorative stuff, steps, wheels, etc. for your pumpkin will all be extra. You will need to build many forms and jigs as you do this. I ended up hot gluing little blocks to the staves so I could use band clamps around them to pull the stave ends together. Then I broke/trimmed them off afterwards. Don't forget that you will need to devise a way to take it apart in sections, so it will fit through doorways, or your daughter's bedroom might become your workshop and your workshop might become her bedroom. I had 12' wide roll-up doors to go through, so my ball didn't need to come apart.

Another thought, if it doesn't have to have a wood skin, is to build many ribs and then cover it with something thin like fabric - think old airplane design ribs and covering. This method would take much less time. Look at some YouTube videos about covering and re-covering wooden airplane wings and fuselages. You could do it with linen and then shrink the linen with the dope finish or get large sheets of heat shrink plastic sheeting and glue it on, then shrink it to fit with a heat gun like they are doing in more recent years. Hobby size model airplane builders are doing this now.

If you make this, please remember to take progress pictures along with the final pictures. I'm certain that we'll all want to see them, no matter how you decide to build it.

Charley

[Nike Nihiser]

Easy, in my case start off by trying to make it straight. :-)

[Vince Shriver]

Albert
Did you steam bend those ribs or lam bend them? Nice work either way.

Albert, Wondering the same thing.

[Albert Lee]

Albert
Did you steam bend those ribs or lam bend them? Nice work either way.

Now you want boatbuilding skills.

Hi Tom, No, I didnt use steam bend, I laminated them twice.

each post/beam are made up of 9 x 5mm (about 3/16) thick slices, I laminate 3 pieces in one set first, and then glue/bend them again when I have 3 sets to maintain the curve/bow.

[Albert Lee]

If it has to be wood....


If you make this, please remember to take progress pictures along with the final pictures. I'm certain that we'll all want to see them, no matter how you decide to build it.

Charley


Thanks Charley, I have been contemplating in the last 3 days and I making it with staves maybe the best way forward.

the wall section will need to be demountable so it can be disassembled and moved around for assembly. the current pumpkin structure can be dismounted.

the decoration will take the longest time, I havnt had time to think about the interior trim/upholstery. I will come to that when I finish the main structure. here is a picture of what I am trying to achieve.

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will definitely post up the pics when I finish with progressive shots.

[Charles Lent]

Your link doesn't work. Can you try again?

Charley

[Mark Gibney]

How did you connect the ribs together at the top and bottom to the plywood (?) circle?
And how will you move the completed pumpkins? Heavy!

[Jon McElwain]

We just completed a new park in Colorado. Check out the "curved" wood structure. It is made from 1-1/8" marine grade plywood frames with Accoya wood slats. It gives plenty of strength for climbing and weathers extremely well.

Anyway, you could adapt the concept easily for your pumpkin. Use some different stain colors to give it some visual variation. The regular screw pattern on our project looks nice and is a simple way to fasten the slats. Hopefully this gives some ideas for your project!

- Jon

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[Tom Bender]

Ok how about this; Make it from fiberglass cloth and resin. Make each segment separately. To keep your existing structure clean make 2 more ribs and set them up horizontally and form each segment by gravity. Expect to scrap the first one for practice.

You may find that it still doesn't drape well and may have to make half segments. Still much easier and lighter than wood.

[Stephen C Cunningham]

Another thought, if it doesn't have to have a wood skin, is to build many ribs and then cover it with something thin like fabric - think old airplane design ribs and covering. This method would take much less time. Look at some YouTube videos about covering and re-covering wooden airplane wings and fuselages. You could do it with linen and then shrink the linen with the dope finish or get large sheets of heat shrink plastic sheeting and glue it on, then shrink it to fit with a heat gun like they are doing in more recent years. Hobby size model airplane builders are doing this now.

If you make this, please remember to take progress pictures along with the final pictures. I'm certain that we'll all want to see them, no matter how you decide to build it.

Charley

This is kind of what I envisioned as well, though I was thinking tent/parachute fabric. Maybe awning fabric which might not be flexible enough but might ad some geometric possibilities.
If wood or gypsum/plaster, that will be one heavy bed!
That is one cool piece of work though. Can't wait to see the final product.

Steve

[mreza Salav]

Depends how much time you want to spend and for what look. You can build (bent lamination, you can use even bending ply for that purpose) bent slats, say about 3" wide, going horizontally between the ribs you already have following the curve of the circle, say about 6" or so apart going top to bottom. You leave a 1/4" groove on the sides of these slats. Then use plywood to run between these slats and "trap" the plywood in the grooves to take the shape of the curve. You can probably replace the groove with a rebate on the outside of the slats and once you bend the plywood over you will get your plywood surface flush with the surface of the slats from outside. Use glue to secure them. This will give you the most spherical shape.

[Andrew Nemeth]

How about using thin strips with a cove on one side and a bead on the other just like is used to built strip built canoes and kayaks. You could do it either on the inside of your frame, the outside of your frame, or both. If you want removable panels, just cover your already made frame with wax paper to resist glue. Spiral your way up to the top with strips and staples. Pull the staples and fair the sphere. If you need strength, you can fiberglass the faired surface at this point (fiberglass and epoxy will be water clear so you won’t see it). Then you can carefully cut the sphere into removable panels. You may be able to fiberglass the other side of each panel at this point, but you may have to ‘refit’ each panel as the fiberglass will add thickness although you could negate this by building out your frame with 1/16”-1/8” disposable shim of some sort that you ‘strip’ over, once you have fiberglassed over the first side of your sphere, and cut and removed your panels, you would then remove the panels and the thin shim from the frame. Fiberglass the bare surface of the each panel then reinstall to your frame with the fasteners or method of your choice.

If you’re interested in learning about this approach just google “strip built kayak” or “strip built canoe”, there is a lot of info on the web about building boats with this technique. It’s a lot of fun and goes pretty quick, this would go even quicker than a boat as I don’t see where you would need to taper too many strips (which is the time consuming part of a canoe or kayak).

[Tom Bender]

If you switch from fiberglass cloth to ordinary cotton cloth and paper mache you could make it a family project.