DIYAT Switch V4 - IMPROVED/NEW CUSTOMIZER PARAMETERS)

2020 IMPROVED AND NEW CUSTOMIZER PARAMETRIC FEATURES:

• Radial flexure width and the concave button recess are now more proportional to outside diameter changes.
• Radial flexure thickness is now a parameter to control activation force (Lo, Med and Hi). The default is Lo but Hi force will increase the activation force by approximately 66 grams force for the 35mm switch.
• Since the LilyPad Button Board is available in two PCB thicknesses I added an option for Thin or Thick. The default is Thin (.8mm) as supplied by SparkFun Electronics. However the Thick setting will change the base part standoff height to accommodate a 1.6mm PCB thickness (as found on Amazon and elsewhere in the internet).
• Since Thingiverse Customizer is still unreliable, I have posted more STL file options to make it easier to download the size and button style you prefer. There are now 12 file options: small, med and large each with a choice of convex or concave button style. Of course you can still download the OpenSCAD source file and open it in the OpenSCAD application to use the built-in customizer for access to all the parameters.

DIYAT Switch V4 Specifications:

• Switching capacity: 1 to 50 mA, 5 - 24 VDC (resistive load)
• Activation surface: approximately 199 - 1655 square mm (smallest to largest outside diameter parameter)
• Activation force: approximately 204 - 248 grams force (largest to smallest outside diameter parameter; measured with digital scale near center of button; less force required with larger button due to mechanical advantage)
• Activation distance: approximately 0.25 mm (as per SparkFun Mini Pushbutton Switch - SMD specifications)

Discription
This is a simple passive Do It Yourself Assistive Technology switch enclosure similar to DIYAT V5 (https://www.thingiverse.com/thing:3146646). The major difference is the switch used in the enclosure. This version uses a very small "Lilypad Button Board" with low activation force and capable of signal level switching,

This three part enclosure (no screws) makes a small momentary tactile button switch more durable and accessible by providing protection and a larger activation surface. Designed with OpenSCAD, this parametric design allows selecting the build diameter, base style (plain or strap mounting) and button style (recessed or protruding). STL files for the small, medium and large sizes are provided for convenience. For other options use the Customizer. Make sure the custom diameter setting matches each of the three parts saved to insure they fit together. This version features a threaded latch and uses radial flexures for frictionless activation. Although it is frictionless, there is resistance from the flexures which increases the activation force slightly. Here's how the flexure works: https://youtu.be/2EqkSfG4u5U

Note: the switch used in this design is good for signal level switching (loads under 50mA) as is the case for any AT switch based on a PCB style tactile switch. For inductive loads, such as motorized toys that have been switch adapted, be aware of the load current. It can easily exceed 50mA. For loads up to 5 amps look at my DIYAT Switch V5. Although considerably larger, the microswitch used in V5 still has low activation force,

The DIYAT Switch is designed to be simple to build, durable, inexpensive (minimal parts) and customizable in size and style. This design is an assembly of three parts that fit together and must be printed with enough precision to operate correctly.