Diving goggles

What is special about these goggles ?

1. They are a practical way to freedive
2. You can make them yourself

Here is a short comparison chart that illustrates alternatives

	Max depth	Ear Equalization	Eye equalization	Field of view	Optical deformations
Diving goggles	Unknown	Hands free (nose clip)	Not needed	++	-
Normal goggles	10m	Hands free (nose clip)	Impossible	+++	-
Fluid goggles	None	Hands free (nose clip)	Not needed	+	---
Diving mask	None	BTV, Valsava, etc.	Air from lungs	+++	-

How they work

These are freediving goggles, not swimming goggles. You could conceivably use these goggles to swim but if you want swimming goggles, I recommend the most cost-effective and practical solution: go buy a pair from your closest sports store.

The basics of how these goggles work is described in the USPTO patent 20170203159A1 and in the presentation of the indiegogo campaign for Hektometer goggles.

Because the patent is abandoned, and, Hektometer goggles have not been available for sale since 2020, this project documents how I made a pair for myself using hardware from my local FabLab, SoFAB. Even though the principles of operation are similar, the design is fairly different, to adapt to the production tools that were available to me and potentially other makers.

What the result looks like

Credits

A lot of help was provided by Xavier, the SoFAB Fab Manager, as well as a couple of experienced makers: Guy who helped me make the overmold and provided invaluable advice on mold design and plastic injection, Pascal who shared his experience with plastic injection, and Laurent who criticized the design over the course of the 18 months it took me to bring this project from idea to prototype.

Other builds

If, by chance, you decide to make your own based on these instructions, please drop me a note to let me know how it worked and what you had to change to have a working pair of goggles.

How to make one yourself

What you need

1. For the inner flexible skirt:

   • A resin 3D printer for the mold. I used a Formlab Form 3B+.
   • Resin for the mold. I used Grey Pro.
   • 12 5x20 threaded screws to hold together the aluminium overmold
   • 10mm thick aluminium plates for the overmold. I bought 2 10x100x500 plates from Blockenstock
   • Something to cut 10mm tick aluminium plates. I used the services from Decouplaser, a local metal shop
   • A drill press with drill bits (diameter 5) for aluminium.
   • Threading bits for aluminium. Kindly provided by a maker, Guy Mausy.
   • A plastic injection machine. I used a Holipress from Holimaker
   • TPU Plastic pellets. I used SEBS 90A, the recommended flex pellets from the machine builder.

2. For the outer rigid shell

   • A resin 3D printer. I used a Formlab Form 3B+.
   • Resin for rigid parts. I used Grey Pro.

3. For the lenses:

   • Transparent Acrylic/PMMA/Plexiglas sheets (5mm thick).
   • A router. I used an Origin. A manual router should work too but it might be challenging to make accurate guides for the lens shapes.
   • A groover. I made one with sheets of wood, screws, and a dremel.

4. For the lens clip assembly:

   • A simple extrusion 3D printer. I used a Prusa MK3
   • PETG or PLA filament

5. For assembly:

   • A silicon band to attach the left and right side of the goggles. I spent 4 EUR on swedish-style swim goggles to reuse the band that came with them. You should be able to find a similar-looking pair in any swim store online. Replacement bands can often be bought separately.

Get the models

It is is easy to download all the STLs, SVGs, and DXFs from this repository.

It is also possible to rebuild these models from the source Python code after you install OpenSCAD and SolidPython:

$ sudo dnf install -y openscad
$ pip install SolidPython
$ make release

The resulting files will be located in the goggles-XXXX-XX-XX subdirectory.

Print The shell

I have printed the shell successfully on the SoFAB's Formlab resin printer with both Draft and Grey Pro resin. The quality difference between the two resins is not visible but I picked Grey Pro to avoid potential problems with part durabilityy.

I used the Formlab's slicer (Preform) with its default "magic wand" tool for orientation and support.

Print the lens clip and assembly clip

The lens clip, and the back clip can be printed without special care on your FDM printer of choice. I recommend PETG for durability.

Cut the lens

The starting point is a 5mm acrylic sheet that needs to be cut to produce an ellipsoid of the right size with the right profile:

The lens.svg included in the release contains paths that can be loaded into an Origin router and then used to cut acrylic sheets with a 3mm straight bit:

1. Cut along the exterior of the inner path to 4.3mm
2. Cut along the exterior of the outer path to 5mm.
3. Use a knife and sanding paper to clean gently the sides of the lens

Beware of the thickness variability of acrylic sheets: in practice, it seems significant (+/- 0.2mm) for the stock I had access to so you might need to adjust the depth of the second cut.

Groove the lens

I considered buying a cheap lens groover that can be found on aliexpress for less than 60EUR but I ended up making one with a dremel and a couple of wood planks. I used spare oak planks I had around to support the dremel horizontally with plywood for the front face:

The front face has a couple of extra plywood pieces to be able to control the depth of the groove:

Finally, I bought a lens holder to be able to keep my fingers away from the dremel rotating bit while rotating the lens itself with the holder:

The above setup allows me to cut reliably grooves of the right depth (1mm) located at the right distance (1mm) from the lens edge.

Print the skirt mold

The skirt mold is a two-part mold that should print easily with the magic wand default settings of PreForm. Again, I used Grey Pro resin which worked well so far.

Make an overmold

The skirt mold you printed with your resin printer will work exactly once and die a noisy death on your first plastic injection. If you want to inject at least two skirts without printing twice the mold, and if you want to make sure that the two-part mold does not open during injection, I recommend you make or buy an overmold of the right size. I made mine out of 10mm thick aluminium sheets, as recommended by a local maker.

The dxfs for the 6 parts can be found in the release directory. I got them cut by a local metal shop, Decouplaser and my local mold expert kindly drilled and threaded the missing holes for me. The result might be a bit overkill but it worked for me.

Inject skirts

After the overmold is assembled, the skirt mold should fit easily. I needed to sand the mold external faces to make them fit tightly within the overmold.

After injecting a couple of skirts, I noted the following:

• Make sure that the screws of the overmold are very tight to ensure proper injection without flash.

• After a couple of injections, the mold will get warmer. It will expand and will be more difficult to insert and remove from the overmold.

• hold time for the machine and pellets I used is at 10-20s. It seems that the hold time depends on the temperature of the mold itself: decrease hold time when temperature increases to avoid extra pressure at the point where material is injected in the mold.

The skirts should need minimal post-processing: if the overmold is not sufficiently tight, you might need to remove some flash.