Segufix Compatible Locks

Compatibility

These locks are compatible with Segufix systems. The posts are 7.11mm at their maximum diameter meaning they fit easily in 8mm eyelets. 

3 post lengths are included for locking together different thicknesses of straps, and STEP files are included so they can be modified as needed.

The “head” of the lock is more compact than the original Segufix locks.

Printing Settings

I have had good luck printing on standard quality (0.2mm layer height) with 0.4mm nozzle on an Ender3. I use Cura for slicing, however none of these parts are particularly finicky so the settings are not that critical.

Since most of the parts are thin, they end up having no infill, however the slider can be printed with ~15% infill since it is not under any significant load.

The post can be printed at anywhere from 15-100% infill depending on your desired strength. Use wall count to increase the infill, not the “infill” percentage. Because of the way the post is loaded, walls are what contribute most to strength.

With the exception of the removal tool, these parts are designed to use NO SUPPORTS. Use the orientation in the following image when slicing:

Additional Parts

Each lock requires a ¼" SAE washer. It MUST be SAE or it won't fit. 

Additionally, two 4mm diameter, 2mm thick neodymium magnets are needed for the slider. These are very inexpensive from sites like Amazon or Aliexpress. 

Finally, two larger 5mm diameter x 10mm length axially poled rod magnets are needed for the removal tool (key). From testing, simply using 4x2mm magnets as the key for unlocking doesn't work because they are not strong enough to pull the slider away from the washer.

Note: @Collarsmith_333688 left a helpful comment for those who might not have access to the SAE washers:

In the process of printing out a batch. I love the clean support free design. One detail you might want to be aware of: if you scale this up by 1.25 it works with hardware store grade 1/4th inch washers and 5x3mm magnets, both of which were off the shelf items at my local big-box hardware. The tolerances were lower on hardware store washers, so some of them needed deburred to get the post through. That was the only hitch.

Assembly

The assembly of the lock is fairly straightforward but a video is included to make things more clear. Superglue (cyanoacrylate) should be used to fix the magnets to the slider and the washer to the case if the press fit is not very tight.  Additionally, glue should be used to hold the lid to the case once the lock is confirmed to be working.

For convenience, make sure when you are making multiple locks that the magnets in the sliders are all facing the same direction so that the same side of the magnetic key unlocks all of your locks.

Here is a render of the how the lock works, which is also acts as the assembly instructions.

Update: A removal tool STL is now included that fits 5x10mm magnets. Use as shown:

Troubleshooting

The slider and barb should move freely within the housing. Any catching may prevent the lock from opening when the magnetic key is applied. When printing the parts, the settings may need to be tuned to prevent “elephants foot” that could mess with the fit.

For convenience, a few extra STLs are included with the suffix “Loose Fit”. If you are running into tolerance issues, try using these files instead. They have more generous clearances that will allow for more variation in print settings at the expense of more slop in the mechanism.