Thanks! I’ll be sure and post more progress pictures.
I expect I’ll have about 22-26 lb/ft^3 worth of Boyancy, with early “stick weights ont he float until it sinks” testing seeming to be in line with that. I should have a theoretical depth rateing of between 3,000 and 6,000 meters for the float itself, though the plywood base would likely have issues. it’s encapsulated so it might survive longer than it would unprotected. The rest of my ROV structure (particularily the pressure hull tube) at this point is only rated for around 150 meters, so it is overkill at the moment. I have no idea how well the 3d printed parts are going to hold up to depth. They were printed at 100% infill and have no void spaces, so they should do pretty well. The robot claw servos probably won’t work past 30m at this point.
I made a built up mold with a permnanet piece of thin plywood as the base, and then wax paper lined cardboard for the sides. The inner thruster intake was 3d printed, and the mounting screw holes were made of several standoff and plumbing pieces bolted to the base. I also bolted an embedded section of 20mm T-slot and the front lift ring, as well as the handle from the former video housing that makes up the rear pressure hull to that plywood. Once everything was bolted in and level, I used Duct tape to reinforce the sides.
A couple lessons learned, and why i have so much bondo on that thing:
The heat of curing syntactic epoxy foam will melt thin wall 3d printed parts. A wall thickness of at least 3mm should be used, otherwise you will get some warping of the embedded part.
Duct tape reacts to Epoxy Fiberglass. Badly. Don’t use it where it might come into contact or it will basically become the surface of your casting at that point.
Wax paper Melts. Once it melts, the paper inside the wax will happily permanently stick to your fiberglass. Use a mold release agent instead.
Cardboard for form edging isn’t a great idea.
even though it looks set, don’t set your float on the top of a 5 gallon bucket in the middle and expect it to not warp slightly, inflicting hours of needless corrective work.
I have a left over bucket shaped foam float now too from what was left over that I didn’t use. So if anyone is building a ROV the exact diameter of a 5 gallon bucket, let me know.