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Giant Inflatable Pigeon

A large inflatable shaped like a pigeon. Designed in Fusion 360 and cut on the Zund.

Giant Inflatable Pigeon

I have this friend – Andi. He's obsessed with pigeons. We went to New York for one Thanksgiving and after a while walking through New York City realised we'd lost him. After frantically retracing our steps we eventually found him fawing over the pigeons. Apparantly they were are soooo different to South African pigeons. Anyway, I thought it would be funny to make a giant inflatable pigeon.

What does a giant inflatable pigeon look like?

Have no fear Dall-E is here.

Bad Dall-E ImageBad Dall-E Image
Bad Dall-E ImageBad Dall-E Image
Bad Dall-E ImageBad Dall-E Image
Bad Dall-E ImageBad Dall-E Image

Ehhh. Maybe not those, but with a bit of prompt engineering I got these two which I based my inflatable around.

A good Dall-E Image – I like how the abs look hereA good Dall-E Image – I like how the abs look here
A good Dall-E Image - I like the recess in the middleA good Dall-E Image - I like the recess in the middle

Design Goals

Specifically I wanted to

Desiging in Fusion

So using Fusion is definetely not how inflatables are normally done (they're usually more like stuffed animals where you design 2D sewing patterns in something like illustrator, etc), but I wanted to continue exploring the Sheet Metal tool.

The basic flow for using sheet metal is supposed to be:

Unfortunally, this just didn't work. To begin I sketched two ellipses and lofted them together with the flange tool.

A rough CAD I made 2D designs based offA rough CAD I made 2D designs based off

Then I tried to make a flat pattern.

A 3D object in my supposed 'flat' patternA 3D object in my supposed 'flat' pattern

But it just came out 3D. Ok, but I forgot to include a gap in the ellipse so there's no where that it can fold

So then I included a gap and still there was no luck. I unfortunally messed up my Fusion history so much that I've got no pictures so show of here.

So, after trying the above and a lot more for a few hours, I eventually just took what I had made and started sketching 2D profiles.

First was the base of the pigeon. For this I drew an ellipse of width 55cm and length 30cm

Base of the pigeon bodyBase of the pigeon body

Then the body of the pigeon. This was going to be a rectangle which wrapped around the ellipse base and acted as wall. I calculated the cirfumerence of the ellipse with which would be sewed together to make the ellipse wall. I was space constrained since I only wanted to use orange

Walls of the pigeon bodyWalls of the pigeon body

Next up was the head and arms. For the head I used the spline tool to draw which looked sort of head shaped, and for the arms I drew a rectangle attached to a circle. The rectangle will be wrapped around and sewn to the circle to give a buff arm impression.

Head and arms of the pigeonHead and arms of the pigeon

Then was the tail (just a rectangle with a square on the end), another arm, and also the top of the pigeon. I wanted to make a lip which would attach to a smaller inner ellipse wall. I copied by base ellipse and offset it inwards so I'd cut out both the lip and inner ellipse in one go.

Tail and lip of the pigeonTail and lip of the pigeon

Finally, there was the wall for the inner ellipse. Exactly like before this was 2 rectangles

Internal walls of the pigeonInternal walls of the pigeon

Cutting it on the Zund

The Mars Lab in the Media lab has a The Zund which is a flexible and precise gantry machine which has modular end effectors. Basically it can do anything you would want to do in 2.5 axis. For my casee I just wanted to cut.

I exported all my sketches as DXFs and sent them to the lab staff member. We had some slight concerns with the size of my fabrics. In my quest to make everything (bar the base and beak) orange I hadn't left much clearance between the pieces and side (like ~1cm) but in the end in turns out all my measurements had been wrong which was great here since it left some extra room and everything ended up cutting great :)

All the cut piecesAll the cut pieces

Sewing this together

This took much longer than I thought it would (8 hours) and a lot of stuff went wrong so I'll list them out here:

Refilling a bobbin

Keeping with the theme, I wanted to use orange thread. Since there was a lot of stuff my bobbin eventually ran out (actually it ran out twice), which meant I needed to refill it. Unfortunally, I set this up wrong the first time and when I told the machine to start spinning the thread slipped off the bobbin and wrapped around the underneath part. It wasn't pretty but thankfully, I was able to take off the bobbin and easily cut the thread.

Sewed all the way around

For the abs my plan was to sew a crease on the front part. Unfortunally, while doing this I forget to do just the front part and sewed the crease all the way around. After asking around some people suggested I use a sew ripper to get it out

Before this I had never used a seam ripper, and thought they were some magical tool which made removing seams super easy.

False.

Seam rippers are just tiny sharp edges which you can stick underneath a seam to try get it out, but it's incredibly tedious. So I spend the next hour going in and out of my seams to remove it.

Orientation

Orientation with sewed pieces is hard. I sewed the beak onto the head first and then onto the body. Except the head came out backwards. Ok, I got my trusty seamripper, and took it off. And then sewed it back on in a different orientation. Yep, it was different. A different kind of backwards. So I called over Alayah, who gets this spatial stuff much better than me, and we eventually figured out which pieces had to be sewed together to get it to work right.

Vinyl cutting eyes

Once everything was made (a.k.a 8 hours later at 10pm) it was time to add on the eyes. I got some heat-on Vinyl, plugged in the iron and cut out white and red circles (technically pigeon eyes are usually orange, but I'd already used so much of that and sometimes the eyes are red so I'll go with it). Then I placed the vinyl on (careful to have shiny side up), heated it with the iron and then removed the basic. Viola, the eyes

Heat-on VinylHeat-on Vinyl

And finally, everything was ready to test

Completed pigeonCompleted pigeon

I got a hair dryer, plugged it into the back and voila

Inflated pigeon 1Inflated pigeon 1
Inflated pigeon 2Inflated pigeon 2