[v2.2] QtQwiicCliq - DIN mount for Stemma Qt/Qwiic/Thing Plus/Feather/Raspberry Pi Zero

LICENSE

Copyright © Herr Brain 2023.

This source describes Open Hardware and is licensed under the CERN-OHL-P v2.

You may redistribute and modify this documentation and make products using it under the terms of the CERN-OHL-P v2 (https:/cern.ch/cern-ohl). This documentation is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN-OHL-P v2 for applicable conditions.

Note: the license notice at the bottom of this page is incorrect.

Description

This is v2 of qwiicplate, my solution for mounting multiple small PCBs on DIN rails. Like the original, there are variants for the Sparkfun Thing+, Adafruit Feather, and Raspberry Pi Zero families of boards. This new version makes a number of improvements:

• New name: QtQwiicCliq, a.k.a. “cutie quick click”
• Separate base models (with standoffs but no holes/studs) for easier modification
• Split parameters spreadsheet into multiple smaller sheets (better organization, changes are applied faster)
• Thinner base plate means faster printing; ridges along the sides maintain rigidity

All of these plates have M3 holes spaced 51mm apart and are designed to fit my DIN clips.

Designing a durable PCB mounting stud

You may have noticed that the PCB mounting studs in the *-stud models are not just simple cylinders. Developing a design that would fit snugly given the print and PCB tolerances was fairly difficult, and I actually tried a number of variants.

Originally, I created a simple “bulb” shape. While it did fit, it also broke off very easily, so I had to rethink the design.

Mireaze in the E3D discord server came up with this clever design, which uses very small (10-100μm) slots in the model to force Cura to create additional perimeters. I made a few variations on this approach, and did get one or two of them to work, but they were painful to model and PrusaSlicer would often fill in the gaps rather than creating extra perimeters.

I decided that I needed a different approach, so I tried this “clover” design. In comparison to previous attempts, the layer adhesion for the studs was significantly improved. While this did work, it was somewhat complicated to model, and it had some visible print artifacts on the standoffs.

After another redesign and some some fine tuning, I ended up with the final stud design. This design greatly simplified the stud shape and reduced print time while retaining the improved layer adhesion of the “clover”. The profile is deceptively simple, requiring only an equilateral triangle and six arc segments.

Print Settings

Print with a 0.4mm nozzle and 0.2 or 0.3mm layer height. I used 0.3mm and 3 perimeters. PETG is recommended since it has good layer adhesion and is less likely to crack when inserting screws. I do not recommend PLA because it tends to be brittle and have poor layer adhesion.

Updates