Prepping For Finishing Touches

As of this evening, I have completed almost all of the final parts that will comprise the monarch butterfly. I am only missing antennae. The wings are now constructed with 3D printed veins and a white canvas like textile, very light weight. Also, the electronics work well and the construction of a control box to house the Pololu board, switches, and connectors was enjoyable.

After completing this build for the first time, I needed to make several adjustments to the steel axle rods and connecting bolts. I also discovered the abdomen is too long so I will sew another one. The discovery of true proportions and how pieces fit next to each other is surprising and magical. The parts alone don’t seem very significant, but when they nestle well with each other in an overall assembly, like the thorax, it makes me think of a creating a kit product.

The final monarch pieces before first assembly.

Here is a list of the parts in the image:

• Wing pair front and rear

• Wing axles, linkages, and ball screws

• Scutum

• Scutelum

• Prosternum

• Mesosternum

• Metasternum

• Head

• Abdomen

• Servos

• Six legs, two tiny front legs, and four larger rear legs

The body still needs the white dots which cover the real monarch butterfly. I’ll do that as an ultimate final touch, as well as a little hair trimming here and there. The monarch has longer hair like structures on its scutelum, abdomen, and front pair of wings.

I am creating a video of the project as well, so in a month or so I will release that online.

Learning From a Rough Draft

I decided to push a rough draft monarch as far as I could to make sure I had a better concept of the full process. You never know if you get all the way to finishing touches and discover that you forgot a critical component or method of construction.

Closeup of the head and thorax of my rough draft monarch

Dead insect eyes become reddish and shallow.

The rough draft I created had several successes and failures. The successful part is that I was able to get four wings to slowly flap, as desired for the final product. The textile choice for the body worked well, and I really enjoyed the head and eyes. The eyes were actually reddish because I used a red PLA for the head and painted it. However, dead insect eyes become reddish and nondescript, while living insect eyes have a great deal of depth and color. I think I will print in black for all body parts and use a gloss finish to create that living illusion.

I discovered the construction of the wings was too challenging. I need to make this part easier on myself. Also, synthetic black velvet does not take color from paint well, so I need to find a new material or change the type of paint. I think I will use a white or lighter colored velvet and try spray paints and then touch up with acrylic later. Many friends recommended silk velvet, which I find poetic in a morbid way.

Finally, I was unable to complete the legs, however this process is more forgiving, The legs are shiny and black and I already know each body segment that needs to be created. The trochanter, femur, tibia, and tarsus. The coxa will be fused to the thorax, similar to real lepidopteran legs.

I had enough information to make improvements and I purchased the final servos. I am planning to use metal gear servos in a much higher quality construction. The rough draft was using cheap plastic servos I had acquired for casual projects. A long term use project needs much more durable and long lasting servos. I hope the Savox SH-0265mg will work well.

I also began working on the Blender model and decided to create a render during my process to share here.

Render showing new components as well as stand ins for bolts and ball joints which I use for boolean subtractions.

I will begin 3D printing the new components soon and trying them out. I need to consider cable paths and durability around the wing joints. Also, I have separated the front and rear wings and I am going to try a cylinder in cylinder method of synchronizing them with the servo linkages. At such small scales, the 3D printer is not very accurate or strong, so it may be better to simply use small bolts to attach them.

I also purchased a smaller Pololu maestro servo controller board. This allows me to easily program the servo movements in a pretty small circuit form factor. It is PC only software, but the scripts are quite simple for repetitive motion. I can convert one channel as the button input.

I wonder how servo signals work over long cable paths? At 50 Hz (analog servos), that is close to mains electrical AC frequency. At 300Hz (digital servos), we may be getting close to when geometry and cable construction is critical. I need to avoid interference or signal loss.

Time is moving quickly on this project, so it’s important to stay on top of this work!

Monarch Butterfly Structures and Creative Materials

Flat bed scan of a monarch butterfly in high resolution. The scales of the wings are visible.

The monarch butterfly is just like any other insect in the materials comprising its exoskeleton. The coloration and texture we see in butterflies is due to scale protrusions from their exoskeleton. The wings especially are famous for colored scales creating the entire image pattern found on the wing.

When creating a larger than life analog to this organism, several challenges arise in copying structures of this detail. However, there are abundant materials that an imaginative creator could use. What really aids the search is a careful examination of the organism in question, and note our observations. This image was a scan of a monarch butterfly at high pixel resolution. The image allows you to see the wings in very high detail. This image is also available on my Flickr, Monarch Scan.

The scales are very regular and each scale is a single color. Areas that show shading or color gradients are different ratios of two scale colors. The thorax is covered in a short hair fur that is black and white from head to ovipositor (this monarch is female). The legs have a hard surface.

Fabric found in San Francisco that seems inspired by monarch butterflies.

I keep a constant eye out for insect-like materials. I am especially fond of textiles that use repeated stitches to produce organic structures. This black and white fabric I found at a local San Francisco fabric store called Britex, It looks very close to the thorax of a monarch. In some cases I wonder if the designed material was inspired by insects, and now I discover it to use in an insect. It wasn’t super cheap, but I really enjoy it. I am also a fan of black and white velvet in various qualities. That structure is scale like and thin. In some cases fake fur also suffices.

3D printed prototype with velvet glued to the exterior.

After modeling and printing with several iterations, I have a functioning flapping mechanism in a thoracic box. I decided to quickly test a method for gluing velvet to the plastic pieces and observing the results. The black color hides a lot of detail, so the plastic structure underneath doesn’t need to be an exact mimic of the butterfly exoskeleton, but the effort does aid in the overall shape and scale. Printing in black plastic will be better than red. I still have a lot to experiment with finishing touches including the proboscis, eyes, and antennae.

Attention to Monarch Butterflies

In 2018 monarch butterfly populations in California reached a super low number. This is after years of steady decline. For environmental awareness and a call to action, I want to attract attention to monarch butterflies.

I am building an larger than life animatronic monarch butterfly. I am looking for support in displaying my 2015 piece and assistance in the construction and displaying of a new and larger piece currently in development.

Animatronic Monarch Butterfly created by John Espey in 2015. Embedded servo motors, textiles, and mixed media.

In 2015, I constructed a monarch butterfly with embedded servo motors to flap its wings (image attached).  As an artist, my intention is to explore insect physiology and behavior using larger than life scale models with integrated electronics.  I hope these insectoid robots encourage viewers to think differently about their relationship to insects, as well as the incredible biomechanics they employ to survive.  I majored in Biology and have used my background in science to inspire my work. The relationship humanity has with its environment is reaching a new level of complexity and global awareness. We are discovering the critical importance pollinators, like monarchs, have on our food supply, climate, and biodiversity.

I propose to construct a new and purpose built animatronic monarch butterfly based on my previous piece with mechanical and aesthetic improvements.  The piece I built several years ago functions well as a static sculpture now. I want to build a new one with improved accuracy and strength. The new mechanics will help the piece last extended exhibition time, and refine accuracy to the monarch butterfly physiology.

Please reach out to me through my contact if you can envision a home for these pieces.

3D Modeling and Printing Exoskeletal Componenets

The monarch butterfly’s exoskeleton is composed of various sclerites and comprise mechanically functional groups. These groups are pulled and distorted from internal elastic muscles. In robotics and animatronics, motors and gearboxes are the muscle equivalent and made of rigid components. The thoracic box of the monarch will function as an enclosure for servo motors and mechanical linkages.

3D print of the thoracic enclosure. Looks like a heart!

I am using Blender to model the butterfly thorax enclosure. This enclosure is 3D printed and assembled with a variety of organic clasps and joints. It has been difficult to create these joints and adjust tolerances with the 3D printer, but I am getting closer to a comfortable shape.

I'd like this to be an homage to the monarchs, and rally attention and support from viewers.  A larger than life animatronic monarch may encourage all ages and personalities to think deeply about what these insects mean to us.  We need to encourage global and environmental awareness as well as excite an interest in science and education.

Early draft of the monarch thoracic box and servo linkages.

Concept rendering for a twelve times scale monarch butterfly with rotating wings