Fresh Rondelles

Overview

While cutting a slice of lemon for me tea, I realized that the remaining part of the lemon finishes in the fridge, in a plate, small but always to large, that sometimes disappears at the bottom of the fridge.
I decided to print a small plate, with some capability to press the lemon in the plate so that there is less oxidation, without using alimentary film.

A serious project?

The first prototype was also an occasion to play with PLA flexibility (I'm a 3D printing beginner). It was original, but not handy, and not flexible enough to handle even slightly smaller or bigger lemon than my “model”. I sent a picture of the prototype to my Colleagues Raphael and Emmanuel. We had a good laugh. Emmanuel found the official name of the project “Fresh Rondelles”, that sounds funny in French. They demonstrates a communicative enthusiasm, convincing me to move forward.

I was focused on exploring flexibility, and decided not to use more obvious solutions, like a threaded rod, to achieve the pressing function. 

Tribute to holdfast

The solution came from my woodworking passion : the holdfast. 
Actually, you could consider Fresch Rondelles like just a small workbench with a rectangular doghole, and a specific holdfast!

And like for usual holdfast, it's easy to use : push on the top to press, push on the side to release, that's it. 

There is only one difference with the woodworking version : the friction coefficient between plastic pieces being not exactly the same than for metal to wood contact, I added a rack to get a reliable blocking effect.

I recently saw several videos on Compliant Mecanism, and curiously Hosdfast is never mentioned among examples, although it is probably the holdest and one of the most widely used for centuries. 
Anyway, I'm happy to pay tribute to this old tool here.

The main prototypes :

One step further

One of my colleagues asked me if he could also cut slices with the device. 
Actually yes. 
After envisioning far too sophisticated solutions, I came with a simple one, and just pocket the plate 3mm depth.  So that you can cut, horizontally, 3mm slices, by sliding the knife on the plate wedges.

Be cautious, keep your fingers out of the way! 

Clean and easy result.

Slice in the glass, Lemon safe back in Fresh Rondelles, everything is in order!

Printing

I printed both part in PLA, 20% infill.

NB : not all PLA are food-safe, and some other printing factors should also be taken into account (post-treatment, printer cleanup, noozle material, printbed adhesive residue, etc. 
More on that here :  https://www.sculpteo.com/en/3d-learning-hub/3d-printing-materials-guide/food-safe-3d-printing-materials/)
Thanks to @BertUK for raising the food compatibility point!

For the base, you need no brim or support. The holdfast part lying on it's side is thin, and brim is highly recommended.
It's important to print the holdfast lying on its side, for obvious flexibility and resistance reasons. 
(You can't pretend to be serious Woodworker if you don't take into account the wood grain : same here in 3D printing!)

Note that, if you intend to offer it, you may insert customized text directly within Prusaslicer (and probably other slicer also).

Design

The FreeCad file is provided.  

It's far from being a good example of robust FreeCAD file. I have done it quick and dirty, and any modification may results in topological naming problems, or just unaligned stuff. But it's overall pretty simple, so you'll find your way through.

The font (Exaggerate BRK © ÆNIGMA FONTS - Brian Kent), does not come with FreeCADn and may not be installed on your system.

To Do List 

• add a “PLA recycling” icon
• add a “No Dishwasher” icon
• Maybe reinforce the part where the knife will hit the handle