4BDN Jetboat hull

thingiverse

This is my latest stepped hull, a work in progress. Lots of advantages come with the steps and specific tile orientations that affect boat handling behavior. I'll be CNC routing a model and creating a mold from the model. Stay tuned for updates. 14/1/2020 Printability! I hate models that require use of support structures to print. However, after my updates I posted below, I realized that the saved split finalised model wasn't from the latest render. Retracing my steps, I found that the render failed at a particular point, and I suspect it was after I'd saved an STL in a different format program than OpenSCAD. Doesn't seem to be any way around it. So I've printed a stern piece with some manual assistance near the holes above the jet unit. It's not great in that region but it's quite usable. Next time I'll add supports. The Bow: I had planned to print it stern end up, bow pointing towards the heated bed. This looks great with support added up to 250 layers, and I'm using 0.3mm per layer. So the whole thing appears quite printable, although a bit heavy in filament. I still have about 2.5 days of printing to complete it. I'll be sealing each section before assembly, still not sure if I'm going to use bitumen tape from my resin infusion supplies or glue or blue-tac. The 6 mini servo holes have a cable duct underneath and are general purpose except the two centre ones are reserved for steering and the option of a vertically trimmable steering nozzle mod. Plan is to fit the servos in with bluetack or power tack sealing all around the servo and cables in the servo mounting hole. Shouldn't be any need for screws, the steering load on my nozzle design is very minimal. Bottom two holes above the stator attaching point are for control rod boots. If you only use one then fill the other. Top two holes are for cooling water in from the stator and warmed water out from the ESC and motor. Don't lengthen the battery side motors or you will be wearing a sad face when the ESC caps blow. 12/1/2020: Been printing the stern. Found a region that didn't show in the 3D renders that prints so thin as to effectively be holes, either end of the intake tube. So I've created voids for up to 5 x hobbyking Rhino 5 amp hour 50C 3S LiPo batteries, a 150 amp water cooled ESC, up to 4 mini servos, an FJD intake and a grunty 1700kv motor. Also created internal holes and nut fitment pockets for SS Threaded rod fitting to tension 3D printed parts for additional support, now looking seriously at 3D printing this in parts. I've also constrained the outer dimensions of the hull: "resize([280,650,100])" which will let me print it in segments diagonally in my FLSUN cube printer. 17/12/2019: Switched out original hull with "fluidity 4BDN Hull.scad" with slightly changed stator cavity and with an intake pad to simplify jet unit mounting. There is a 3 degree downward tilt for both intake and stator. I'll also be updating here: https://www.rcgroups.com/forums/showthread.php?3483031-4BDN-hull And there are some stators I've designed here: https://www.rcgroups.com/forums/showthread.php?3441451-4BDN-FJD-35mm-stator-alternative (These fit to the FJD inlet and impellors on the same forum.)