Daft Punk helmet

12/31/2017

How about something completely different?

Here's a silly project I rushed together for Halloween '17 (only posted 2 months late, a new record!). I've never really made any costume props or "aesthetic" projects before, so I learned my fair share of Bondo, sanding, painting, and ergonomics lessons. We're all human after all, right? With a busy schedule, I really didn't have enough time to complete this to the level of detail I wanted. In the end, it came down to the usual late night rush to get it in presenting order. It was a fun process nevertheless, so please enjoy the pictorial timeline below:

Like any good new 3d printer owner, I was eagerly perusing Thingiverse for instant gratification projects when I came across "Daft Punk Thomas 3D Printable Wearable Helmet" by bendiger (thanks!). Instant gratification might be a stretch with this one, but between the well designed .stl files and an excellent instructables build guide built around this model I decided to give it a shot.

2-3 weeks of 3d printing in

My 3d printer, especially when printing at high feed rates to finish by the deadline, leaves something to be desired with dimensional accuracy. While the pieces are designed to be zip tied or bolted together, I opted to hot glue fit them first (to maintain flexibility), then epoxy and fiberglass the inside for the final connection. This was a mistake, as I learned later in the process.

For the LEDs (because of course it needed LEDs), I opted to stray from an authentic representation of the Thomas Daft Punk helmet and instead go for maximum obnoxiousness. Amazon has a cheap 1-wire protocol addressable RGB LED flexible matrix product that happens to be about the right size, as well as the same LEDs in ring form for the ears. Both of these products are compatible with the Adafruit NeoPixel and NeoMatrix libraries.

Fit check selfie

The Y-height of the matrix was a little tall for the helmet. Because the LEDs are addressed in a snaking fashion up and down the columns, it would have been a major pain to snip off a row and resolder the connections. Instead, I opted to just offset the matrix further back into the helmet and adjust the code to not illuminate bottom or top rows when showing things like text. 

To get this out of the way upfront: no, you cannot see when wearing the helmet. There's no way to poke holes in the matrix, the helmet slits below the matrix only let you see peoples legs and the ground, and I ran out of time to get a camera and internal LCD screen working. I found that typically though, people are too blinded by ALL THE LIGHT AND BLINKING to notice you stumbling.

Beginning the fiberglass layup

With the helmet tenuously glued, I laid up a thin layer of fiberglass on the interior. While strong, the resin and fiberglass mostly laid flat against the surface, rather than getting into the "root" of the joint between panels (as it was still filled with hot melt rubber). Like a weld, poor root fill doesn't lead to a strong joint.

Next up was the Bondo. I've never worked with the stuff before, but I was impressed by how quickly it would dry to a sandable state and how much you could remove with ordinary sandpaper. The smell and dust, however, was substantial. A respirator and adequate ventilation are a good idea.

One quick sanding session later

My first round with the Bondo I only applied a thin smearing over the interface between different panels. It quickly became apparent that sanding the PLA helmet pieces to remove 3d-printing layer lines was a substantial task, as was blending it with Bondo'd areas. I ended up recoating the entire helmet before settling in to a 2 hour sanding session. I picked up Harbor Freight's cheapest palm orbital sander, which ended up being essential for the early sanding stages.

Proud of my sanding job, I primed the helmet, waited for it to dry, and came back to check the result.

It wasn't great. Gaps, scratches, and high spots were everywhere. I gave a small section a spray with metallic spray pain, and the imperfections were amplified even more. There were only a few days to go, but I couldn't have been proud of a final product with such flaws. Hating myself, I re-sanded everything again, until the lowest spots were back down to bare plastic.

After many hours of Bondo'ing, hand sanding, and repeating, I finally had a result I could accept. I don't have any pictures of the re-primed helmet (because it was late at night by that point), but I went ahead and started with the metallic spray.

I ended up giving the helmet 2-3 coats of the metallic spray to get the best finish possible. To speed the process, I set the helmet out in direct sunlight for half an hour to dry. When I returned, to my horror, the helmet sections had started shifting in the heat, spreading and rising like tectonic plates. Visible lines were appearing all over the joints, some even cracking. The hot melt glue had softened in the heat, releasing stress between the pieces and allowing them to flex against the fiberglass. Without many other options, I cooled the helmet back down again and resanded each visible joint, following up with a touch-up paint job. There are still faint lines visible from this incident.

Before any more harm could occur, I decided to start installing the LEDs. I began with the ear rings, 3d printing a 2 layer thick diffuser that could be glued over the tops of the LED rings to spread the light. Both ear rings were run by an Arduino Nano I found laying around, and I wrote a spinning animation with a fading trail to get a cool effect:

Next came the front matrix, which was glued in place and wired to a separate Nano on the interior. The one-wire protocol running these LEDs is very timing sensitive, and I found I couldn't get animations as fast as I wanted on the big matrix if I tried to run everything off a single Nano. Luckily, I had expected this and soldered into two microcontroller sockets on the helmet's protoboard. To power the helmet, I re-purposed a 4S quadcopter lipo that I could conceal in my pocket. I added a replaceable 5A automotive fuse holder inline as close to the lipo as possible. Theoretically, the front LED matrix could draw up to 15A, so I only programmed animations that used lower power and turned down the brightness to avoid permanent eye damage.

Even for low power systems, it's always essential to fuse high current capable batteries, especially if you're carrying them on your person. Relying on the wiring running next to your face to act as the fuse when a downstream wire shorts is an undesirable failure mode, as is waiting on the battery to self-limit current. Especially as the accessibility of lipos has increased, it's alarming how many hobbyists are using them unfused because they don't expect their project to draw much current or don't understand the risks.

To bring the voltage down to acceptable levels for the LEDs and Arduino voltage regulators, I used an inexpensive DC-DC converter from Amazon. The reviews online warned of a tendency for capacitor explosion, so I started by bolting on an aluminum cover that would hopefully at least catch the shrapnel if that happened. I added Kapton tape to minimize the risk of touching and shorting components, then ran it under load for an hour ahead of time to make sure it stayed cool and seemed reliable.

This was thankfully uneventful, so I located the DC-DC in an ear cavity and ran the helmet's internal wiring.

Selfie #2

After another fit check, 2 things were apparent: internal padding was needed to keep the face from drooping, and it quickly got hot inside. With one night to go, I threw in some insulation foam and scavenged a computer fan to build into the chin.

"Danger fan", as I termed it, had a bad habit of grabbing fingers, hair, and glasses as I squeezed my head into the helmet. Fortunately, it was just me wearing it, so I accepted the paper cuts and moved on to programming some animations.I also produced a visor to go over the LEDs. Unfortunately, I ran out of time to tint it a darker color and my attempts to add diffusing to it didn't go well. I ended up wearing the helmet without a visor, and it don't think it affected the result too much.

The lights don't show up great on camera, and I don't happen to have video of the final product at the moment. When I do get around to getting some video, I'll add a link here.

I have renewed respect for all the unbelievably detailed and meticulously made costume helmets on the internet. Most of them put my efforts here to shame. If it were to make this again, what would I do? Probably print carefully, do a much better initial job at Bondo'ing and sanding, and improve the fit and finish quality of the interior. And not use hot glue. At all. The reflectivity of my paint job is also a far cry from the actual article. But most of all:

Work it harder, Make it better, Do it faster...and probably make it stronger.