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Diablades: A Product Development Case Study

Background:

As a fun project, and as a focal point for a review video, we design and created the Diablade spring stilt product. As you can see above, Joel (the 3D Printing Nerd) had a pretty good time bounding around our shop. ​

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Process:

Any product development, especially one that can put a YouTuber's health at risk, involves a good deal of prototyping. Here, we only had time for a single (single round and single foot) proto. This proved out the utility of our connecting pieces, the stiffness of a bow "limb" as the main spring, and the practicality of TPU printed parts for foot capture.

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Rolling our learned lessons into the second design, we decided to use two crossbow limbs (much stiffer) per leg - one as the spring, and one as a strut up the calf. We also moved the strut to the rear of the leg rather than the side to offer more support (perceived or real). ​

This project is designed to use as many H-Series capabilities as possible, which are described below:

3D Printing

The H-Series is a true multi-tool 3D printer. This gives us the freedom to design in a number of different types of materials - not just different colors, but also different durometers or material types.

Toe Box: 60D tread pad with 98A Upper

  • Harder material at the bottom provides structure

  • Softer material provides compliance for fit

Heel Support: 98A outlines, 60D infill, 88A tread (shown below)

  • Harder material as infill provides structure

  • Semi-flexible material for main body provides flexibility and toughness

  • Low-durometer material provides grip

Strap Pad: 98A outlines, 88A infill

  • Low-durometer infill material provides compliance for comfort

  • 98A material provides durable exterior and better printability

Grip: 88A outlines, 98A infill

  • Low-durometer skin for maximum friction on polished concrete

  • 98A material for structure to prevent buckling

​​Calf support: 98A TPU with Ionic support (shown below)

  • Excellent compatibility between Ionic support and TPU materials. 

  • TPU used for bed adhesion layer and for infill of support body (only the skin layer of the support body needs to be dissolvable - the infill can be less-expensive)

  • Soluble support allows for much higher quality bottom surfaces than break-away, especially for smooth organic shapes

  • Desiccant cabinet is crucial for hygroscopic materials like many dissolvable supports

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Heel Support (left) and Calf support (right)

Hybrid (3D Print and CNC) and Multi-Axis
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Combining 3D printing and CNC milling offers many advantages, mostly demonstrated with this build.

Toe Support: Carbon Fiber loaded PA6 (Nylon)

  • CF-Nylon is a strong, easy-to-print material that mills beautifully

  • Printed fast with a 0.8mm carbide nozzle at 0.4mm layer height

  • TPU region is used as an aid for bed adhesion and a standoff to allow clearance for the cutter, so the part can be milled all the way to the bottom.

  • Milling provides excellent surface finish and tight tolerances (necessary because this part clamps to the toe rods.

  • 4th-axis setup makes it easy to cut features from different angles

  • Touch probe and pendant make it easy to do more complex setups like this. 

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Flipping parts over automatically for final operation

Rotary Printing
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We have gone over this a lot, but there are some great benefits to rotary (vs. cartesian) 3D printing.

Leg Pad 88A hexagonal mesh

  • Rotary build strategy enables printing of otherwise impossible geometries

  • Cylindrical layers provide a stronger finished part 

  • This part has a cylindrical bore, but this method is not limited to purely cylindrical shapes. 

  • Rotary axes connect to machine easily (plug and play)

CNC Milling
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The H5 (and H4) are, at heart, CNC machines. They take files straight from CAM software and use them to make chips. There are several aluminum parts on the Diablades that were milled on H5 machines:

Spacers: Aluminum 6061, 3-axis, two setups

  • Flat vise workholding (standard with H5)

  • Second op easily located using integrated touch-probe (also standard)

Toe rods: Aluminum 6061, true 4-axis (shown below)

  • 4th axis allows simple workholding with ER32 collet, and easy access to all sides of stock

  • True 4-axis motion provides accurate features around a cylinder (here, chamfers around the holes)

Core: Aluminum 6061, 3-axis, 4 setups (first setup shown above)

  • 1/4" cutter with ATC for up to 14 available tools

  • Integrated touch-probe and part tabbing for fast setups

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Coordinated 4-axis Milling of Aluminum

Conclusion

There is obviously a lot going on here - that is what the H-Series is all about: incredible capability; requires effort to operate. But this is all doable for a single person with a computer (CAD/CAM) sitting in front of the machine (our 1-person, 1-computer, 1-machine concept).

If you've made it this far, thank you. If you would like to see the design files of the Diablades to make your own, feel free to reach out with the contact page below.

And if you haven't already seen Joel's video about this process and the end result, you can find that here: youtube.com