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Design, Mechanical

REV: 2020-12-02

Unit

We use metric dimensions.

We try to use metric parts, materials, and tools where possible and practical.

Fasteners

THREAD SIZE.

We use M2 to M12 threading for all small to medium-scale applications.

Our standard increments:

  • M2
  • M2.5
  • M3
  • M4
  • M5
  • M6
  • M8
  • M12

M2 and M2.5 are the smallest sizes with common-stock and tooling-support. It is used in miniaturized devices such as car-remotes and phones.

M3 is our standard for small mechatronic devices. We usually prefer the marginal robustness over compactness (compared to smaller threads).

M4 is our strong standard for lower mechanical loads. It offers a proof load over 3000N (property class 5.8, middle-curve). It is used in the VESA international-mounting-standard.

M5, we don't use much because it's marginally different from M4 and M6.

M6 is our strong standard for higher mechanical loads. It is dimensionally close to the half-inch imperial-standard and therefore offers good universal compatibility. It is the threading standard for mechanical jigs such as aluminum-breadboards for optical experimentation.

M8 and M12 are reserved for specific applications requiring high-strength or high-opening-diameter (ex. circular-connectors, cable glands).

HEAD DRIVE.

We use philips, hex-socket, and torx.

We prefer hex-socket head-drive for most applications. It is a strong and practical balance of tool-accessibility (ex. hex keys are common), strength (ex. less stripping of driver-bit/device than philips/torx), and ease-of-assembly (ex. can be driven at an angle with ball-ends).

Philips optimizes for tool-accessibility. Saves time!

Torx optimizes for driving-strength. Improves mounting-torque (useful for getting the most out of small fasteners)!

MATERIAL.

  • A2 stainless steel (SAE 304)
  • A4 stainless steel (SAE 316)

Ergonomics

A super common problem we see is a lack of rounded, chamfered, and deburred edges/corners! This affects not only ergonomics but also safety and reliability! Sharp corners can get dirty and cause infected cuts. Rough edges can abrade wire-jackets to various failure conditions.

Cleaning

Preferred: easy-to-clean, see process list below.

  • tool-free wipe
  • tool-free scrub
  • tool-required scrub
  • cold-water rinse
  • hot-water rinse

FASTENERS

  • Dowel, Screw
  • Helicoil