Parametric Box - FreeCAD Edition

Important!

A few people have messaged me stating that they're getting errors when trying to change the box parameters. I'm running Linux and using version this version: https://github.com/realthunder/FreeCAD/releases/tag/2022.07.09-edge

Specifically, I'm using https://github.com/realthunder/FreeCAD/releases/download/2022.07.09-edge/FreeCAD-asm3-Stable-Conda-Py3-Qt5-20220709-glibc2.12-x86_64.AppImage

Whether you're running Linux, OSX, or Windows, I'd suggest using a STABLE image dated 2022.07.09 if you're having issues with the box.

Update 11MAY2023

I received another message about the box not working on Windows. Since I've switched back to using Windows recently and am using the same version of Linkstage3 FreeCAD, I also encountered issues. I've uploaded a new version of the box, v2, that now works on Windows. I anticipate that it will still require Linkstage3. However, I've retained the old design so that Linux users can continue to use it. Unfortunately, I can't verify whether this box works on Linux at present since I don't have access to a Linux box.

Description

This is a parameterized box designed in a forked version of FreeCAD, Linkstage3. To modify the box, install and open the design in FreeCAD Linkstage 3. In the document tree, you'll see a spreadsheet named “Parameters.” Double click on the spreadsheet to open it and you can then modify many parameters. Descriptions of each parameter are included in the spreadsheet.

This box is pretty much a direct knockoff of Yanev's design. I want to use this box for work purposes, but did not want to pay a license for Fusion360.

Hardware

The default design utilizes M3 screws, quantity of four with 30mm length and two with 35mm. If you do not use the front handle, you'll need six at 30mm and none at 35mm.

There are parameters in the FreeCAD design that will allow different sizes of screws.

• ScrewInterferenceFit - This should be set to a little smaller (about 0.1 to 0.2mm) than the diameter of the screw you want to use.
• ScrewLength - This sets the length of the screw you intend to use.
• ScrewHeadHoleSize - This adjust the project panel that you can optionally screw down into the box. This does NOT adjust the size of the hinges, the length of the ribs, or anything else. In other words, if your screw is too big, it isn't going to work. I wouldn't go significantly larger than an M3 screw.

Updates to the Original

• Easier printing - Most of the chamfer angles have been changed from 45° to 60° to allow for marginally easier printing. 
• Gasket - In Yanev's design, the gasket channel was sized to allow for the use of either 2mm rubber band or a strip of 1.75mm TPU filament. The channel size on this box is identical to the original, so the 2mm rubber band or 1.75mm TPU filament should still work. However, I've added a gasket to the design so that you may be able to print it and have a closed loop. The gasket doesn't make it water tight, but it does improve water resistance.
• Handle - A handle has been added. This handle will adjust to fit the box as it is resized.
• Project panel - There's an optional ledge that can be included within the box bottom. This ledge allows for mounting a PCB panel or a printed panel. On the PCB / panel, mount power supplies, Arduinos, Raspberry Pis, joysticks… whatever you desire. There's also a panel included in this FreeCAD file which will adjust to match the box parameters you specify.

Modifying the Box with Parameters

To modify the box parameters, open the FreeCAD project (again, use Linkstage3!). Find the Parameters spreadsheet in the tree view, then edit any cells highlighted in yellow. I've made attempts to test changes as I went to limit the fragility of the design, but there are likely some holes. Don't use negative widths, non-positive radii, etc.

Exporting the Box

When your box is sized appropriately and you've verified that it is ready to go, you'll need to export it. Unfortunately, LinkStage3 does not support exporting 3MF, but it does support AMF which (in my opinion) is pretty much the next best thing.

1. In the Tree View, select all of the items you want to print. Use <Ctrl> to perform a multi-select. Note that the latches are identical, so you only have to export one of those and print it twice, or export both.
2. Select File → Export 
3. Enter a file name and change “Files of type” to “Additive Manufacturing Format”
4. Select Save

This will save all items associated with this box into a single file, making it easy to keep track of it. You may find that you want to export one printable object a time, and that is not a problem.

Handle Stupidity

I made the handle calculation pretty dumb. It just reaches from the mounting point down to the bottom of the box. If you make a very tall box, you may find that your handle is wonky looking. To get around that, adjust the box back down to a smaller height, export the handle, then set the box back to the size you desire.

Disabling the Project Panel

If you do not want to use a project panel, you may want to suppress the panel ledge. 

1. In the Tree View, expand BoxBottom
2. Look for and right click on ProjectPanelLedge
3. Select “Suppress”
4. Look for and right click on ProjectPanelMountingHoles
5. Select “Suppress”

When the box is exported, it will not include the panel ledge. You can add it back in by repeating this process, but select “Unsupress”

Project Panel

The intention of the project panel is to allow organization and mounting of off the shelf parts or to allow you to design your own PCB. Here's an example of a project panel for an Arduino, Power Supply, AC power inlet, etc.

Slicing in PrusaSlicer

These instructions assume you exported the entire box as a single .AMF file. 

1. Open the .AMF file in PrusaSlicer
2. You will be asked if this should be treated as a single object with multiple parts. Select No.
3. You will now have a bunch of parts all stacked on top of one another.
4. Under Print Settings → Skirt and Brim, set Loops to 0 (you may need to enter Advanced view mode)
5. Drag everything off of the print bed.
6. Select a part to print, put it on the print bed, orient the part properly, then slice.
7. Repeat until everything is sliced.

Part Orientation

• Handle - Rotate 90° about the X axis
• Latches - Rotate 90° about the Y axis
• Box Lid - You'll need to flip the box lid about the X or Y axis by 180°, and 90° about the Z axis
• Gasket - 90° about the Z axis
• Box Bottom - 90° about the Z axis
• Project Panel - 90° about the Z axis, and 180° about the X or Y axis. Note that there is a 0.2mm thick layer within the panel. This is a sacrificial support layer and provides support to the screw holes in case you add features to the bottom side of the panel.

Revisions

• 28AUG22 - Updated latch geometry again, found another way to break it while changing parameters
• 27AUG22 - Updated the latch geometry as I noticed it was broken in the last upload
• 25AUG22 - Initial release
• 04DEC22 - John Doe reported an issue with the latches on the uploaded .amf examples. I believe this issue was previously fixed in the FreeCAD document, but I neglected to fix the example uploads. The .amf files have been removed and corrected .3mf files have been uploaded in their place.