Orthodontic Expander Key Holder

My child recently had an expander placed in her too-small mouth, but we were only provided some large metal keys to turn the jack screw. My large fingers not having space to turn the key led to gagging and fears that I could easily drop the key down her throat. We needed a better solution.

After seeing a commercial device on Youtube, I looked at purchasing one, but they were only sold in bulk packs and had longish lead times. I found a printable version on Thingiverse, but it uses a snap-fit design and 3 of my 4 attempts to make it broke while snapping it together. I was afraid it could still easily break while in-use, leading to a potentially dangerous situation.

This design is glued together to ensure nothing can break apart. The two small circles form the pivot for the key. These pieces are glued together with just a drop of glue (I used super glue) and the design limits the possibility of glue from interfering with the smooth motion. The metal pin ‘key’ is then glued in the 1.5mm hole as well.

We’ve used this version for a week (10 turns of the initial 30 needed) and it’s infinitely better than manual key alone — it has made what was a very stressful task for my daughter and I into an easy routine that will ensure we make all the necessary turns of the expander. This device is vastly smaller than my fingers, so she’s not gagged while turning the screw and I have no concerns about it accidentally falling apart.

Print Settings

Printer Brand:

Monoprice

Printer:

Maker Select

Rafts:

No

Supports:

No

Resolution:

.2 or less

Infill:

Any

Filament: Any Any - I used PLA

Notes:

Super easy to print. Mine finished in less than 15 minutes despite my old, slow second hand printer.

An 'elephant foot' will impede this device from working smoothly, so be sure to have enough compensation to prevent this. I set my Elephants Foot Compensation to 0.2-0.3mm to be sure not to have issues.

Post-Printing

Assembly

Insert the larger diameter plug into the hole in the handle. Place a small drop of glue (I used super glue) in the middle and place the mating price into place. I spun it in place while the glue set just in case any glue squeeze out wouldn’t lock-up the pivot.

Then glue the appropriately sized metal shaft that matches your expander into the 1.5mm hole. I cut the tiny handle off of the orthodontist provided key, but a thick paper clip could be the right size and might work. Mine is about 7/8" or 1" long with 1/2" visible.

How I Designed This

Source File:

This object was made in Tinkercad. Make a copy and edit it online:

https://www.tinkercad.com/things/b5oJ4uNQ15Q

Category: Household