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3D printed toe door pull

A project log for Hands-Free

hacks to avoid touching shared surfaces in public spaces

John OpsahlJohn Opsahl 03/22/2020 at 04:200 Comments

The toe door pull is the next style of hands free door pull device I have decided to design for 3D printing. It is essentially a toe cup that you hook your foot under to pull the door open (see example image below). Commercially available versions can run up to $100 each. The first revision of this design is similar the commercially available designs but after a round of testing I believe this 3D printed design can be made much simpler.  

An example of a commercially available toe door pull.

Initial target for these 3D printed designs has been be able to print them in six hours or less. One strategy I use to achieve quicker prints is to design them in a such a way that support material is not required. This requires that no undercut surfaces are at angles larger than 45 degrees relative to the build plate surface and that undercut surfaces are continuous. One of my favorite parts about this project is imagining the geometries that both achieve design intent and meet "no support material" requirement.

I ran a stress analysis on the part to understand how it might realistically deform and break during intended operation. I don't have high confidence in the numbers generated by the simulation and use it primarily as a guide on where to add additional stiffness/strength to the part. For example, after noticing that the highest stress was near the side screw mount, I added a larger fillet between the screw hole and toe cup to increase strength at that location. A 900N (200lb) load was applied to the inside face of the toe cup.

The design printed in six hours and ten minutes. I used 30% infill and 0.8mm wall thickness. I am a little worried that the angle of the toe plate is too shallow and user's toe will slip out of the cup. Hope to get it mounted on a door and start testing soon.

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