Here is an example of how I added three bulkheads to one of the Bristlemouth dev kit end caps using a 2D stencil and a drill press.
This is the end result: one underwater pressure sensor + pressure vent + wetlink cable penetrator all fit snuggly on the end cap.
Step 1
Create a 2D template for where to install the hardware. I used the CAD models to check for interference with the assembly tool + nuts that need to get installed on the backside of the end cap.
Note, there is a engraved shape on the top surface of the end cap, this is the “safe zone” to install your bulkheads or other hardware. It’s a general recommendation - be sure to check the inside of the end cap to verify you have room for any tools or fasteners that might rub on the inner wall. CAD is a good tool for this.
Step 2
Print out scale 1:1 and tape it to the end cap. Use a punch to transfer the center marks for your holes to the end cap, this prevents the drill bit from walking around on the surface and makes things more accurate.
Step 3
Drill out the holes. I suggest using a small drill bit to create a pilot hole, then progressively use a larger drill bit to work your way up to the final hole size. I used 3 different sized drill bits.
The plastic material is POM which can be brittle and chip easily. Take your time to make a clean and accurate hole. The bulkheads that I am using use a small o’ring to mechanically seal against the end cap - if the edges of the holes are jagged this could cause issues for your o’ring seal.
I suggest securing the end cap in place during the drilling process. Use a piece of wood and a clamp or some other way to hold the part in place while you drill. This helps to create an accurate and clean hole.
Nothing fancy, just a scrap piece of wood and c-clamp.
Step 4
Install the hardware using the required tools + following the manufacters guidelines for assembly. Bluerobotics has a set of special tools that are designed to fit in tight spaces for their wetlink connectors. These tools came in handy for this install.
Here you can see how close the tool gets to one of the nuts on the other bulkhead. It’s a tight fit, but it works! The CAD for the tools can be downloaded from the manufactures website.
And there you go. Go slow and take your time to carefully determine where you want to add the bulkheads using CAD and make clean holes with a drill press. It’s always helpful to have the right tools for the job.