Looking for advice on a cylindrical build...

[Jared T. Beattie]

I've got a request from a director to make a set based on a series of classic old play blocks, as shown below, except blown up to adult human size, ie: Babes in Toylands style...

Seems simple enough right?

Except for those cylinders, (and less so the arched curve)...

I've already heard some methods using Sonotube, or concrete form tubing, but I'm unsure if that will be sufficiently strong for weight bearing, either stacked as seen here, or especially when used as a block for a 180-200 lb. actor to stand on. thoughts?

I've also heard about FlexiPly and other products that will "wrap" in that manner, but it seems theese types are materials are both expensive and hard to obtain without direct ordering from a manufacturer. Again... thoughts?

Also worth mentioining it will be a touring set, so anything that really amps up the weight may not be viable.

In summary, what are yr go-to methods for building with simple (or complex) curves?

Thanks everyone, I'm a total n00b here!

 

[sk8rsdad]

Sonotube should work fine if sufficiently braced. In the case of the vertical tubes, use a tall plywood X inside to transfer the weight of the superstructure to the floor.

The semi-cylinders need some other method and extra reinforcement where the actor stands. Although having an actor stand on a curved surface several feet off the ground sounds like a workman's comp claim waiting to happen. Another construction option would be flexi-ply but it might not handle that tight a bend radius. Failing those options it could be built up using lots of slats then smoothed into curve with liberal sanding and filling.

 

[Van]

A lot depends on your Budget as well. You can build-up layers of Wiggle-wood/Bendy-Ply. Two layers of 1/4 with sufficient backing is quite strong. Remember when ordering Wiggle-wood it comes in two flavors: 'Hot dog' which bends along the long axis. and "Hamburger" which bends along width of the piece. Sono-tube is a great item as well, is has a LOT of rigidity, the biggest issue with it is killing the spiral seam lines. The best way I've found is reversed vinyl flooring. Yes, with the 'bottom' of the vinyl facing out.

 

[Jared T. Beattie]

Thanks, sk8rsdad! I think the sonotube route will work for me. I hadn't put the ply X-bracing together in my head for whatever reason, and now, with that, I should be able to do what I need. I should have been more clear too, I'm only building a tall cylinder or two, the half-cylinders just happen to be in that source photo.

 

[Jared T. Beattie]

...the biggest issue with it is killing the spiral seam lines. The best way I've found is reversed vinyl flooring. Yes, with the 'bottom' of the vinyl facing out.

I'd heard this a bit. I was at first thinking just filling putty, but would not bind and/or end up drying and cracking out even with paint?

 

[Van]

I'd heard this a bit. I was at first thinking just filling putty, but would not bind and/or end up drying and cracking out even with paint?

Correct, getting anything to seal those seams is difficult. Since the tubes are, essential, cardboard and they're coated with wax. It is possible to sand the face of the stuff, then you might try to use latex caulk to fill the cracks but getting it perfectly level is a pain. Either the vinyl solution or using heavy grade rosin paper will work a lot faster and easier IMHO.

 

[BSchend]

Also note that in an effort to increase storage capacity similar sized sonotubes will be different actual diameters. For example, 3 different 12" diameter tubes might actually be 12", 11.5" and 12.5".

 

[kicknargel]

I bet sonotube will be good, but just want to mention: you don't need to go direct to manufacturer for bending ply/wacky wood/flexiply. Many good, non-big-box lumber yards will carry it. I have it in stock from at least two places within 5 miles of my shop.

 

[darinlwebb]

Might not be quite what you're looking for, but for a recent build I had to make a large grain-bin type thing, about 10' diameter, and that was right about the smallest diameter that you can bend 2" lauan strips before they threaten to snap. I essentially built a cylindrical grid out of lauan, with 2x4 vertical supports every 90°. The skin of the thing was 20" foam tiles, so I made that the size of the grid and we hot glued the tiles on.

Now to make sure that the actors don't crash in to it.

 

[josh88]

I bet sonotube will be good, but just want to mention: you don't need to go direct to manufacturer for bending ply/wacky wood/flexiply. Many good, non-big-box lumber yards will carry it. I have it in stock from at least two places within 5 miles of my shop.

What nick said. we've got 2 versions of wacky wood in our shop. barrel and column type. One bends on the 4 foot edge and one bends on the 8 foot edge.

 

[JohnD]

Is it time for a wacky wood wiki? What are the usual terms for direction of bendability, column and barrel or hot dog and hamburger?

 

[kicknargel]

I've also heard "long-axis" and "short-axis." So dry.

 

[bobgaggle]

my supplier uses 4x8 or 8x4 sheets. where 4x8 gets you an 8' tall cylinder and 8x4 gets you a 4' tall cylinder

on a side note we had a rep from kerfcore come by the other day, they've got some awesome products that bend

 

[josh88]

Is it time for a wacky wood wiki? What are the usual terms for direction of bendability, column and barrel or hot dog and hamburger?

I'm actually surprised there isn't one, given the direction qualifier and that it has so many names... wacky wood, wiggle wood, flexply, bendy board, I'm sure there are others. The logic at least in our mill for barrel and column is that barrels are short cylinders and columns are tall cylinders. Ours are actually an inch oversized in each dimension, 49x97