Now it's finally time some concluding thoughts about this project.
First the expenses. Building a proper housing is not a cheap hobby. I documented most of the expenses and the total cost for the housing was about 350 euros. Most of this is just materials since I get to use the milling machines etc. for free. The materials are expensive at least here in Finland especially when you buy just a small piece at at time. The most expensive part of the housing was the Ikelite 5503.15 dome which I bought second hand for 100 euros.
Material Pcs Price per piece eur Total
14 mm bull end mill 1 37,65 37,65
Aluminum for the body 1 37,94 37,94
Latches 3 7,9 23,7
Aluminum for the port 1 17,55 17,55
Dome 1 100 100
Springs for the buttons 10 3 30
Stainless bolts etc. 30 0,6 18
O-rings for the buttons 10 1 10
O-rings for the port and back cover 1 10 10
Polycarbonate for the back cover 1 24,6 24,6
Piece of PC and stainless steel 1 4,4 4,4
Anodization 1 30 30
Bike spokes 2 0 0
Aluminum for buttons
Misc cutting tools
Piece of stainless sheet
Second, the time used. I did not really keep track of the hours, but I can try to estimate. Creating the CAD model took probably over a hundred hours even though the housing was very similar to the previous one I made. I started really building the housing just a couple of weeks before the trip but after that I spent most of my time doing it. Therefore, the building part was probably also around a hundred hours, including making the toolpaths for the CNC machines. So all in all maybe 200 hours.
And the lessons learned.
1. Start early if you have a deadline. Really early. Building anything takes longer that you think.
2. If you want to get things ready, try to use off the shelf parts. For example, I partly remade the back cover latches and they turned out to be on of the weakest spots of the housing. On the other hand I could not find exactly the kind of latches I wanted so my options were limited.
3. Design properly and well. CAD modelling is essential. I had not completely assembled the housing a single time when we left for our trip. Even so, almost everything worked as planned because all the parts were fitted together in the CAD model. The FEM simulations also eased my mind regarding the rigidity of the housing. It also took me just a half an hour to make them. I don't know if there are any free FEM packages available for stress simulations but if you have access for a FEM program, a simulation is very easy to make when you have the CAD model.
4. The 3D printed prototype was great in testing the ergonomics.
5. Polycarbonate seems to develop cracks in time if it is under constant stress. Even though my polycarbonate parts were never in contact with any solvents, I still got cracks in some threads of the back cover. I think the screws should just not be tightened so much.
6. Design the o-ring grooves properly. Remember that the o-ring adds friction to the buttons and the friction is larger the more o-ring is compressed. Think also beforehand how you are going to install the o-rings. They can be a pain in the ass to squeeze into a tight groove on the bottom of a bore.
7. Make everything from plastic or stainless steel, also the springs, bolts, etc. Also most aluminum alloys will oxidize in salt water if they are not anodized. Anodization can be done at home and it is not too difficult, just requires some experimentation with the dyes. On the other hand I paid 30 euros for anodizing the main parts by a professional so a DIY setup may not even be the cheapest option.
I guess that's all that comes to my mind now. DIYing is a great hobby but if you just want an underwater housing, it's easier to work some extra hours and save money for an off the shelf housing .