Overtightening Screws: A Design Improvement Update (SlideUnderV2 incoming)

At DockedByDesign, customer feedback plays a crucial role in how my products evolve - especially when it relates to real-world use.

Recently, a customer reported that one of the bracket arms of the SlideUnderV1 broke after a screw was slightly overtightened during installation. Even though this was the first time this occurred, it was important for me to fully understand what happened and how to prevent it in the future.

What the testing revealed

After extensive testing, I found that because the SlideUnderV1 is 3D printed vertically, the layer lines run horizontally. When a mounting screw is overtightened, the additional force can cause stress between these horizontal layers, potentially leading to separation.

It’s difficult to define an exact threshold, but testing showed that approximately 1.5 extra turns beyond hand-tight can already introduce excessive force. While this may not sound like much, it equates to over 1 mm of additional compression, which is enough to create unwanted stress in this specific orientation.

The solution: a two-phase improvement

After evaluating several options, I decided to move forward with a two-phase design improvement.

The first phase introduces a revised screw cutout geometry combined with a dedicated rivet. This rivet is printed in a circular orientation and is designed to sit precisely inside the updated cutout. Its purpose is to distribute clamping force evenly and prevent horizontal layer separation when screws are overtightened.

The key idea behind this solution is simple:
the washer is as thick as the dock itself, meaning the screw tightens against the washer and desk - not directly against the dock body. This effectively clamps the dock in place while protecting it from excess compression forces.

Current status

The updated design will be implemented for the MacBook Pro 14” version of the SlideUnderV2. After further validation, this improvement will be rolled out to all other models.

As always, I appreciate the feedback that helps make DockedByDesign products better, stronger, and more reliable with every iteration.