The Benchy Hat

(Copied from my blog)

(Update 2023-07-19, I have posted this model on MakeWithTech, which provides an online copy of OpenScad and a web interface to enter in the parameters)

I made my Benchy Hat for Open Sauce 2023. The most common comment after "Nice hat!" was “Where can I get one?”

In a simpler world I would just post an STL file. But we have two problems:

1. Human head sizes and shapes vary considerably. With this design, and being made out of stiff PLA plastic, a proper fit is key to comfort (and it not falling off your head).
2. The terms of the Creative Commons license that the Benchy is published under does not permit me (or printables) to redistribute a modification of the Benchy. I can point you to the benchy. I can even offer a copy on my own website. But I can't offer an altered benchy.

To get around these two limitations I am not distributing the final product at all. I will be teaching you how to make this style of custom hat for you or anyone you wish to make a hat for. And as you will be making your own modified benchy, everone is happy. You'll just need:

• An STL file that you wish to wear on top of your (or someone else's) head.
• A copy of OpenScad
• The ability/desire to edit a text file
• Access to a 3d printer (and some filament)
• Access to the head that you want to fit the hat to
• Some felt spacers

Positive features of this design

I can't say that I made a complete survey of every possible way to make a hat with a 3d printer. I was trying for a simple gag that would:

• be pulled off in a single print on the printers I have on hand (an Ender 3 and an Ender 5).
• focus on doing something cool with ordinary material. So, if possible, PLA.
• preserve as much of the original benchy aesthetic as possible.
• be comfortable to wear all day, and not impede normal show-going activities.
• stand up to normal levels of activity without falling apart

Downsides of this design

• This hat has to fitted to the individual wearer.
• I still needed felt spacers to maintain a gap so my head could naturally cool.

The Design

In my minimal research I discovered that making a hat light is the key to keeping it comfortable. I used to work all day in a hard hat, but they aren't very comfortable. A hard hat typically weight around 15 oz. (426 g.). So that was my upper measure. One source the stated a weight of between 80 g. (3 oz.) to 115 g. (5 oz.) as being "easy to manage" for a hat. Another source stated the weight of a typical ball cap as between 3 oz. (86 g.) to 4 oz. (114 g.). Plus or minus an ounce. So helpful.

The final weight of my hat was around 280 g. (10 oz.). Which was relatively comfortable. But to pull that off I had to stick to 2 0.4mm perimeter walls, very sparse infill, and the bare minimum of ceiling and floor layers (about 4). Anything less would look bad/fall apart. Anything more adds weight.

The Fit

I did some minimal research into hat making. I found some handy charts with ranges of sizes, and distributions of humans who fall into those ranges:

I also tracked down the template for a simple hat that I knew fit me:

But while distributions are nice... they don't help me fit my particular head. And the simple hat template was only simple because it was made of fabric that could stretch to the shape of my head. In fact, as it turns out, most hats are deliberately made small so that your head stretches the fabric. This helps a hat actually stay on. Terrible plan for a plastic hat, though.

So the process of fitting my head ended up being a game of educated trial and error. Over 5 versions I developed a skull cap that fit my head. I also wore the more comfortable ones for several hours to make sure they stayed comfortable.

I worked with simple geometric shapes which together formed a solid hull. I would then hollow out the hull to form a shell. (See the HeadPan module inside the file). For my test fits, I added holes to allow me to feel how off the fit actually was:

But for now we will focus on editing Benchyhat-v1.0.scad

The user serviceable parts of the file are at the top:

Sizing a hat

Unfortunately, the CAD file as written doesn't really lend itself well to translating from conventional hat sizes. The default numbers in the cad file fit the same head as fits in a 55cm circumference bucket hat. Play with the numbers. Do some test printouts. Dial in the exact size for you and yours.

Assuming heads are all the same shape, here is a rough chart of how the parameters for the design would scale up or down for different sized heads:

A 1st percentile (1%) person is very small. A 99the percentile (99%) person is very large. An 50th percentile person (50%) is average. But, of course, all heads are a little different. So you'll probably be printing out a few test prints. I recommend using the settings drawBenchy=false and helmetHoles=true when doing test prints. The hole option lets to poke a finger or a measurement instrument through to see if there if there is extra space.

TIPS:

My hat printed without supports on an Ender 5 S1. You have to turn it 45 degrees to allow it to fit on the build plate. The overhangs inside the helmet were a bit messy, so I cleaned them with a dremel too.

While I did end up with a hat that perfectly fit my head, I did find the need to place some felt spacers at the top. They provide an air gap to allow sweat to evaporate, and not condense and drip into my face. You have to use a lot of them to distribute the weight of the hat over a large surface area of your head.