Filament Hinge Box - V1 - Parametric - FreeCAD 1.1.0rc2

Minimum FreeCAD version 1.1.0rc2

Customizing the dimensions and amount of hinges for this box can be done with FreeCAD, minimum version 1.1.0rc2, you can download it from this page https://github.com/FreeCAD/FreeCAD/tags - find the most recent "1.1" version in that list and download the appropriate build for your operating system

(do not use version 1.0 to open the attached FreeCAD project, it's pretty much guaranteed that 1.0 will not be able to properly open a 1.1 project version).

Customization instructions

Open the .FCStd file in Freecad, the dimensions can be changed in the "dimensions" spreadsheet:

Only alter values in the "Alterable parameters" column, do not touch the "Computed Fields" column unless you know your way around.

Be patient!

After changing each value wait for the program to become responsive again, the document recomputes all the model at every change, this may take several seconds if not more depending on your computer.

The size of hinges along the different directions is determined by the overall size of the model and amount of hinges along each direction, you can see the computed sizes on the right:

With the above values, for example, you'd get something like this:

The model is set up to be printed from the flattened version right away, you may need to tweak the clearances according to your printing settings and desired result, remember not to touch anything from the computed fields column:

Preview of the configuration

You can check the results of your configuration at any time switching over to the "box" and "flattened" parts, make sure you only keep one item visible at a time (click the "eye" icons in the tree view to toggle visibility of each item) to reduce clutter:

Hinge test print

Once you're happy with the configuration, to reduce the chance of bad prints you may want to export the hinge test part (only keep "hinge test Part" selected in the tree and select File > Export).

The hinge test part will change according to your settings (width of the box for the length of the test part, length of the hinges for the width of the small plate holding the test hinges together).

Print the above test part twice and verify that you can easily assemble the parts together - the default settings will be a relatively tight fit, it may require carefully pushing the filament in with a pair of pliers for long runs of hinges.

Bonus tip: do not grab the filament too far from the hinge, only leave one or two millimeters left to push in not to bend the filament as you try to push it into the hinges.

Alternatively you can increase the hinge inner radius and/or postprocess the printed parts to clean them up of any imperfection.

Final export

For the final export only keep "flattened Part" selected before exporting.

The flattened version can be printed as-is (assuming you have enough clearance between the parts and the hinges), alternatively you can split the object directly in your slicer and rearrange them:

Alternatively you can expand the "flattened Part" section in the tree and select/export one or more sides at a time, separately from the others:

Assembly

Nothing special, just insert the filament into the hinges and cut as needed - you can bend the filament a little to improve the locking or sligthly melt the end (there's plenty videos out there about how to refine such filament hinges after assembly)

Additional construction details

Hinges have octagonal profile both externally and internally, the inner octagon has a small additional angled roof at the top to reduce the chance of floating bridges during the print (such bridges may collapse inside the hinge and make it difficult to push the filament through).

This sketch also computes the projection of the slanted octagon side, to be matched by the chamfer on the lid.

The thickness of the lip underneath the lid is computed subtracting the plate thickness from the outer radius of the hinges, so make sure the plate thickness is always somewhat smaller than the hinge's outer radius, or there wouldn't be any room for the lip under the lid.

The height of such lip you can control directly via "lid_lip_size" in the spreadsheet.

The simplified angle in the configuration (5° by default) is really computed adding it to 90°, in case you're wondering why the numbers don't match between the configuration and the 95° angle constraint in the sketch.

Yeah, I'm done, yay!