After years of having the idea for this project in the back of my mind, I finally decided to go for it. I built a CPS 5 drone a few years back, but I never felt like it was enough for what I wanted to do.
I am naming my ROV “Marlin”. I did not like this name at first, but it is starting to grow on me.
A few goals for this project:
130 Feet / 40 Meters depth capability (since this is the max recreational limit for Scuba in the USA)
Have as many 3D printed parts as possible
Stay under a 2000 USD budget
3 hour run time
6 degrees of freedom
Note: Designed for freshwater
More design work needs to be done once parts start to arrive and I can take accurate measurements to mount them. Mostly referring to the motors and the lights.
I am building my own motor pods mostly for budget constraints, but to also give me the freedom to make modifications as needed.
For the electronics, I am going to be using mostly the basic ArduSub setup using a Raspberry Pi 4B and a Pixhawk.
A few questions or requests for recommendations:
I am looking for a sonar module that is decently compact and inexpensive. Imaging quality does not have to have the highest resolution, but the ones that I have seen far exceed the budget for the entire project.
What is the best way to waterproof 3d printed parts. Right now I am using Bondo, then painting with primer and base coat.
What is the best filament to use? I am currently just using some Polymaker ABS.
Any other feedback or recommendations would be great.
Hi Ted, with the waterproofing of 3D printed parts, do you mean parts such as endcaps/flanges that need to keep the enclosure watertight? or external fairings and brackets? For the later I just use PLA or PETG at 100% infill and design them to be fairly solid and so far they haven’t been a problem after numerous dives (but max test depth is 10m).
For cheap sonars, you could check out these: BASIC Side-view/Down-view Sonar - KOGGER and other products on their site, but stock availability seems to be an issue. I haven’t used them so just a suggestion not a recommendation.
Also the designers of CPS drones once demonstrated Dichtol for waterproofing printed parts, it looked very promising but when I tried to buy it in Australia, it was going to cost $800 a tin.
Mostly focusing on the endcaps and flanges since I want to protect the electronics.
I have printed about 30 percent of the parts so far and they are all at 100 percent infill and a bunch of walls. It makes sense in my head that paint would work to fill in the small gaps but I didnt know if anyone tried that. I am weary to only use 100 percent infill because of the depth I am aiming for.
I will check out Dichtol. It looks a little nasty to play with, but it is worth the experiment.
I appreciate the suggestion.
I was just able to order one, so I will let you all know how it works out.
If you are targeting 40m depth, I would recommend buying a BR enclosure (or one from another supplier that has been rigorously tested). There are many factors that make building your own watertight enclosure difficult. For example its hard to get tubing where which has accurate and consistent inner diameter; 3D printed parts can shrink or expand overtime - so what is watertight on one day may not be on another. If it was me I would try and save money on any part EXCEPT the enclosure. I know you have a budget cap, but a watertight enclosure is probably the most important item in your ROV. I have spent a lot of time designing 3D printed flanged end caps for our test tank which is only 1m deep, and even at that depth it is hard to build a reliably watertight enclosure using off the shelf tubing and 3D printed ends.
While I appreciate your suggestion, that is not the route that I am going to take. I do not see the value in purchasing an enclosure because it would limit my creative freedom. If I find leaking during testing, I will redesign to take that route, but for now I do not see it as needed.
I am basing my design on something similar to what the CPS5 drone uses which has given me success down to 100 feet.
So far I have only been able to test my enclosure down to 20 feet in a swimming pool. After 1 hour at 20 feet there were no issues.
I appreciate the feedback.
Ill be looking forward to posting some more about it once I get more of it together.
