Monday, February 26, 2018

Cardboard Carousel

Rabidly excited today to share with you the last of three commissioned cardboard projects from 2017:  a carousel!

Quick backstory: last summer, I built three projects for the company Minted to showcase their new line of holiday cards in a press release. The first was a mailbox,

and the third was a load-able rotating carousel.

I designed it to hold cards in the landscape orientation

as well as portrait.

Unloaded, this is what it looks like, with the roof on

and off,

to facilitate loading and organizing

 in both orientations.

To hold the cards in place are evenly-spaced cardboard strips creating gutters  on the central tower

and the floor of the carousel,

so all the cards are visually accessible at once.

This was such an enjoyable project - all three builds were, but this one especially. In addition to being an aesthetic display, it also behaved like a toy. And who doesn't love cardboard toys?

Let's deconstruct!

The moving mechanism first. This is the heart of the carousel. What we need is essentially a flat circular surface on which spheres can move as bearings. 

Because the bearings move the carousel in a rotating circle, the bearings themselves need to remain in a ring. In order to keep the spheres from escaping from the ring, there need to be walls containing them. 

But the walls must be low enough to expose the tops of the bearings to do their work - in this case, freely rotate a platform that will rest on top of them.

And this bearing casing needs to be high enough so that that rotating platform is adequately separated from the surface on which this mechanism rests. Here is the finished mechanism with an axle screw sticking out of its central hole. This axle will extend through the rotating platform above it, and provide a pivot about which the entire carousel spins. 

Here is that platform - it's just a flat circle now. It's big next to the bearing case, isn't it?

If we connect it to the bearing case as is, we'll have a simple turntable. If you have kids, this is where they'll bring out their Polly Pockets and Playmobil and turn it into a communal merry-go-round. 

But we need ours to be a card display, so let's keep working. I etched out a circle in the middle and drew equally-spaced radial lines outward. This circle will be the attachment point for the central tower, and those radial lines will be the gutters in which the cards will rest. 

Now comes the most time-consuming part of this project - creating the gutters. On a second circle of cardboard, I drew the same little circle and radial lines and cut apart the segments. Then I shaved off a little of their sides, just enough that when they were glued on the platform, 

they left narrow spaces between them.

Here is the finished gutter-ed surface.

Each of those gutters will hold one card.

Next, I ran a strip of cardboard around the circumference for trim

(and to create a barrier that will help keep the cards in).

Here is the finished platform attached to the bearing casing 

and secured together with that axle screw.

Does it spin? Yes - here's a video!

The roof now - this is a large segment of a circle (I used three-quarters) with scalloped edges.

Corrugated cardboard doesn't roll well obliquely, so instead I folded it along eight edges to create a ribbed canopy rather than a cone.

This is the stem of the canopy.  This will slide into the central tower. What's important here are these tabs - they will be attached to the underside of the roof with glue.

Here are some of the children helping with the painting. We used acrylic paint.

Back to the rotating platform now - this is the central tower. It's just a roll of cardboard glued into that etched circle where all the gutter-ed segments converge. It's just enough wider than the roof stem so that the two cylinders can snugly nest within each other without shifting.

But it is seamless i.e. you can't tell where the edges of the roll overlap to make the cylinder. See this technique in action in this post. This is important because corrugated cardboard is thick, and an overlapping seam would mess up the vertical ribs (see later photos) big time. 

Here are the ribs - they're just strips of double-wall (see this post for different kinds of cardboard) corrugated cardboard

and they get glued all around the central tower. Notice how they meet the radial segments of the platform to create a continuous gutter from tower to platform.

All perfectly aligned. A little fiddly but not as difficult as it looks - because we'd cut identical segments and identical ribs, they all matched up without funky off-sizing.

Finished tower.

Here it is in action, holding cards.

In the landscape orientation, the cards extend all the way to the trim; in the portrait orientation, they don't, but the gutters keep them securely in place.

Here is the finished carousel, embellished and with the roof on. 

In this shot, you can see a little of the roof stem just above the central tower.

As with the mailbox and house display boards, the embellishments were kept minimal, to allow the cards themselves to take center stage.