Hexagonal Prismatic Return Key Holder with Magnets

1.- Motivation

As with all prints I do, all start or from a need or a lust-to-have.

The model was designed to be a return key holder for the 5 rooms rented by my workplace for us in a shared workplace with other companies, therefore there was a need for a return keys holder to be designed.

For the base, I used hexagonal prisms joined together, when each prism has slightly a different height (for giving it a nice look).

For the key chain parts, I wanted to be small and cylindrical object as shown in the cover image.

2.- Materials required:

• 5 8x3mm magnets (I ordered them from Ali Express)
• 5 M4 nuts.
• Super-Glue.
• Double sided, heavy duty adhesive tape (for attaching the base to a wall) 

If you print more then one base,  multiply the number of magnets and nuts by the number of bases you will print.

The magnets I used have the size of 8.0x2.6mm, therefore, the model hole for the magnet has some tolerance and was made 8.2x2.8mm (with a 0.2 tolerance). The tolerance took into consideration that the magnets will slide in the hole with some pressure, super glue can help in keep the magnet permanently.

For the key chain part, instead of using a second magnet, I used a M4 hexagonal nut for easy placement without having to worry about a magnet polarity.

If the sizes are not suitable, you can use Fusion360 attached file for modifying the parameters and then saving it as a mesh (STL file). The parameters to change are:

The marked items above are:

• (1) magnet_diameter parameter (including 0.2mm of tolerance)
• (2) magnet_height (for thickness of the magnet).
• (3) m4_inscribed (for the width across flats, add 0.4mm of tolerance)
• (4) m4_height (for the thickness of the nut, add 0.3mm of tolerance)

3.- Printing the parts

3.1.- Printing the base

For the base, no special requirements exist, because the magnets are inserted after the completion of the print.

3.2.- Printing the key chain part

For the key chain part, in the slicer you need to add a pause print (M601) for pausing the print when the M4 nut should be inserted. I discovered the hard way that the M601 command is not supported by my setup or printer, therefore I used a manual color change at the height of 3.6mm (layer 18 with my settings), that does the job. (Use M600 command instead)

For this, do a left click on the plus signe that appears when you place the mouse pointer at layer height 3.6:

You need to re-slice again, and your GCODE file will be ready for printing.

If your printer respects the M601 command, I guess that is the way to go. (Just right click on the plus signe and select to add the M601 command).

Important Note: After placing the nut, before resuming printing it is important to check that the nut will not have any protruding part otherwise you can damage your printer.  In the picture below you can see how it should be inserted. (notice the space between the top of the nut and the last layer:

The attached GCODE files have two color changes for making the key chain even nicer.

For the key chain part, this is the summary:

4.- Changelog

• Uploaded 30/Apr/2023.

5.- Last Words

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Happy printing & Greetings from the Galilee.

Hope it was not TL;DR