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3D Printed USV hull files available on Hackaday


(Kevin) #1

I found this USV project on Hackaday the other day and the project leader was kind enough to make the 3D files available for download. https://hackaday.io/project/25508-n3m0-the-autonomous-boat

I’m in the process of printing up my own hull and fitting it out with a Pixhawk 2.1 and 2x BlueRobotics thrusters. I think it will come out to be around 1m in length when complete, which is a much more mangeable size than my larger red USV. What I like this the top hatch to seal in all the electronics and I won’t have to use Pelican cases.

I’m thinking about making up two hulls so I can start playing with multi-vehicle options and maybe get some swarming actions going. It makes for a good size for the temperature sensor, a camera, and maybe a small single beam sonar.

It prints ok so far. I’ve had some delamination of the layers, probably due to the cooler room temperature and me not having an enclosure for the printer. Some filling and sanding of the gaps will be needed once everything is glued together.


(Tim Pierce) #2

You can make a temporary enclosure out of turkey roasting bags and a bit of tape. Also with the taz, you can bump the hotend temperature up another 5 degrees to get a better inter layer bond with ABS.


(Kevin) #3

Thanks @piercet It looks like I’ll need to start making profiles in the expert settings. I’ve gotten away with just using the quick print setting sup to this point.


(Mike Holden) #4

Hi, I’m Mike Holden, I designed n3m0. I’m interested to see how it works with the thrusters. We use 2 blue robotics thrusters on our larger boat (Dumbo).

It should be plenty of power, I’m not sure about the prop pitch or how fast you’ll go. We had a lot of trouble with little things getting stuck in Dumbo’s fans this last year but it was record runoff and SF bay was full of trash.

I think ABS is a good choice if you can get the prints to come out.

I’m glad you are documenting your build, I’ll update my instructions as you discover issues.


(Kevin) #5

Thanks Mike, and welcome. I like the two thrusters because I can set-up the software for either ArduSub or Rover with skid steer. I’ll work up some mounts that I can epoxy on the outside of the hull so I minimize hull penetrations. I was also thinking about having wires for the temperature sensor come down through the skeg and mounting it on the back end.

So the hull is finished, but I have some filling and sanding to do. The parts fit together really well and any of the errors you see are from the ABS warping. I’ll get a heat shield for the printer for Hull 02 and see if it does any better.


(Kevin) #6

So filling and sanding has been…fun. I used way too much Bondo and not coarse enough sandpaper so life was rough just returning the hull to it’s proper shape. I’ll have to find something better. Even worse was that I still had the errant leaks, so I covered the entire hull in yellow spray-on PastiDip. It’s waterproof now.

I got the thrusters attached and I’m working on the rest of the internals.


(Per Søndergaard) #7

Looks Nice. What did you use for glue?


(Kevin) #8

30 minute epoxy and then I hit the seams with ABS Glue. Plastistruct was what I had on hand.


(Per Søndergaard) #9

Thanks for the info… :wink:


#10

I came across this while searching about 3D printed boats and hulls. I’m curious how the project is going. I am kicking around ideas again about building my autonomous boat and 3D printed hulls is appealing as a solution.


(Kevin) #11

Hi @waterwander, I discontinued this project quite a few months ago. I could never get the hull sealed up properly and I always had one or two leaks I couldn’t track down. A better material/method needs to come out before we can have good 3D printed hulls.


#12

Thank you @kevink for the update.

I’m curious, do you recall how much material it took to print this?

I’ve ordered 3D printer before and commissioned efforts at my work and now I’m looking at my own 3D printer and trying to get a feel for how many spools are needed for a project of this size.

While browsing around yesterday I also wondered if we could use the 3D print as the mold for say a fiberglass or carbon fiber layup. I think this gets too messy and would rather just find the best way to make a 3D print waterproof.


(Mike Holden) #13

For my boat I used less than 2 rolls of PLA-- I used orange and glow-in-the-dark white for the sections and had leftovers even with several failed attempts.

Here are my thoughts after using the boat a lot. Overall I’m happy with the design, it works well and is small and capable. It will sometimes catch a rail when it leans into a turn, which makes it keep going straight: you have to keep the bow up to keep this from happening. This is mostly when driving RC and turning fast, the autopilot isn’t aggressive enough to do this. The battery lasts quite a while. I haven’t found the ultimate range yet, but my nephew drove it RC for around an hour and it was still going strong. Mine is completely watertight although it took some iteration on the hull and hatch.

I used 2 coats of epoxy laminating resin to seal the hull, this added some weight. It was a mistake to design the hull skins to be 4mm thick and then print them with hollow infill- although this makes them light and stiff it is harder to get them to be waterproof. I hope to print another hull this summer, I will reduce the thickness to 2mm and print it solid, but I’m still working on an effective enclosure for ABS so haven’t done it yet.

I think the bluerobotics thrusters are a bit oversized for this boat, it goes quite fast with just a single prop drive. The thrusters seem to be designed for static thrust which makes sense for ROV use, but this hull isn’t very draggy. Don’t get me wrong, I like the thrusters, I have another, larger boat (Dumbo) that uses 2 of them and they have been great, but it uses four 5 Ah batteries while n3m0 uses just one. I haven’t tried thrusters on n3m0 so I could be wrong here.

I recently changed the payload computer to a raspberry pi with a camera and carry a mobile hotspot on the boat so it can have a long-range internet connection.


(Dominic Garn) #14

Hi, Kevin and Mike I am a Mechanical Engineering student at Cardiff University and am currently working on a USV and UAV project. I came across your feeds whilst I was doing some research and just wanted to congratulate you on your works.

I shall attempt to create a similar autonomous boat project, thank you for the clear instructions and guidance.

Any pointers or further advice before I get going on the project?


(Kevin) #15

@domgarn Cool, best of luck making one! Not really any more general pointers, let us know if you have specific questions and we’ll be sure to assist.