3D printed forearm door pull

A project log for Hands-Free

hacks to avoid touching shared surfaces in public spaces

John OpsahlJohn Opsahl 03/20/2020 at 23:030 Comments

A forearm door pull is another alternative that enables someone to pull open a door without touching it with their hands. They typically sell for about $90 for two of them. It's a simple enough geometry that its no problem to 3D print on the cheap so lets get designing.

The concept is simple. Place your forearm between the hook and the door and pull.

The image below is an example of a commercially available forearm door pull installed on a bathroom door.

The only unique feature of the design that I have contributed is that it can be 3D printed without any supports. Otherwise, it is essentially just a wall mounted hook.

For a quick stress and deformation check I applied fixed supports at the mounting holes and applied a 900N (200lb) force at the inside face. No major concerns from these checks.

The 3D print time is about 5 hours 45 minutes. I used PLA with 30% infill and 0.8mm wall thickness. 

It is probably stronger than it needs to be. On the next revision, I will reduce thickness in some areas to arrive at a faster print time.

The only issue I can anticipate is that your forearm might slip off the inside face of the hook when pulling the door open. To address this I will either lengthen the inside hook face, curve the end of the inside face towards the door, or add a high friction surface on the inside face.

I bought an old public bathroom door from a resale store this weekend so I plan to do some actual testing in the next week or so.