There I was, staring down a crumpled-up tube of toothpaste, contemplating whether it was worth it for me to try squeezing it into infinity or to give up and start a new tube. Just as I was about to throw in the towel, my partner performed a miracle: with the awkward help of a doorframe and through sheer stubbornness, he proudly (smugly) proclaimed “see, there is always more”.
There had to be a better way. And with that, I set off to 3D printing an over-engineered 10-hour 4-prototype solution that cost several tubes of toothpaste in time, energy, and filament. Because that is what designers do.
Prototype 1: Thingiverse
Why reinvent the wheel? Type toothpaste into Thingiverse, wait 30 minutes for it to load, and voila, you have so many options from which to choose. I printed the top result (thanks ChatterComa). With 274 makes it must do something. Only one problem: the slot was just slightly too narrow for one of our tubes.
Print Settings: To FIll Or Not To FIll
When it came to slicing this baby, I wanted speed and strength. It looked like the weak points were around the corners of the gap for the tube. Surely pulling on the tube could damage the part over time. I could print with the standard 2 to 3 walls and some percentage of infill. I don’t always rely on infill for part strength. Sometimes increasing the number of walls (perimeters) of the printed part can result in greater durability with less or equal printing (see: 3D Print faster & Happier: How to choose layers, walls, infills).
But I also had to keep in mind the fillets. When you apply a rounded edge along the z-axis, your layer height determines the resolution of the curve. The fillets on the edges of the tube insert are important here because they help the user align and insert the tube into the slot. So I compromised and printed at a modest 0.2mm layer height.
Given the size and use of the part, I knew I wanted it to be 100% solid one-way-or-another. I chose the Walls Strategy (using more walls than could fit anywhere, e.g. 50), I eliminated the use of infill print patterns. Although for a solid part it isn’t going to make much of a difference, I liked the aesthetic of the concentric lines emanating from the perimeters.
But wait – couldn’t I have just used Cura’s concentric infill and top/bottom layer pattern to accomplish the same effect? Yes! Definitely. But I usually prefer to keep the infill pattern static and change the number of walls, which I usually customized with every print. For a non-solid part where I am using walls and infill, this is my prefered approach.
Prototype 2: Fine, I’ll just do it myself
After that near homerun on the first print, I knew the concept was a winner. There is no need to print one of these fancy tube-twister designs. I printed one years ago. The multi-part print is just overly complicated. The tube doesn’t always align itself well, becomes twisted, and is a general PIA. Not what I’m looking for while I’m trying to save milliliters of precious toothpaste.
The final result of this prototype was great. Although I spilled coffee all over my desk and into the layer lines of the prototype, it was almost perfect. The original mouth size was 62mm by 1.5mm. After testing with our largest tube, this was still not quite wide enough.
The Final Solution
I increased the slot to 62.50mm wide, and decreased the slot to 1.4mm in height. This accommodates even the biggest of tubes while provided a solid squeeze.
The end result is an easy to use toothpaste squeezer. The eyes ended up working perfectly as two finger holes; like a bowling ball. Happy accident. Printed at 0.1mm, the fillets came out fairly smooth. At 100% wall-infill, it will last.
Finally, I will be able to enter 0.1% as waste in this Toothpaste Calculator and stretch out my tubes for years to come.