Introduction: 3D Printed Radio Controlled Utility Boat

By www.electrosync.com.au
About: I'm a designer and creator from Australia with a science background and a passion for open-design projects including CAD design, 3D printing and electronics. My Electrosync project creates obscurely, useful, t…

Introduction

This big 3D printed big radio controlled boat is designed to house water monitoring equipment and other environmental utility systems. The hull is a catamaran design with both sides of the hull connected with carbon tubes. It is capable of carrying a large payload inside the hull as well as on the optional modular deck system. The boat is powered by a brushless motor and air propeller and steering is via above water control surfaces. The boat is designed to be radio controlled. A minimum of two channel radio equipment is required for throttle and steering, more channels are required if you would like reverse and for operating any optional auxiliary systems. This instructable is for the hull and drive systems only and does not include any of the auxiliary systems at this stage, but I plan to add these soon.

Specifications

  • Overall length: 1,000 mm
  • Dry weight: 6 kg
  • Running weight: 7 kg
  • Payload capacity: 5 kg+
  • Maximum speed: ~20 km/h

This design is not waterproof. Parts must be prepared to prevent water entering. I recommend two coats of polyester resin on the hull. A video series showing the design and build process can be found on the Electrosync YouTube channel. Note that there are some differences between the boat in the videos and the boat in this instructable.

Recommended print settings:

  • Minimum build plate size: 200 mm x 200 mm
  • Material: PLA+
  • Nozzle size: 0.6 mm
  • Print speed: 60 mm/s
  • Layer height: 0.36 mm
  • Initial layer height: 0.42 mm
  • Wall line width: 0.6 mm
  • Initial layer line width: 140 %
  • Wall line count: 3
  • Top layers: 3
  • Bottom layers: 3
  • Infill density: 40%

Note

22 STL files that make up the boat are available for free on Thingiverse. It takes approximately 200 hours to print the 81 parts listed in this instructable with the recommended print settings. It will take much longer to print with a standard 0.4 mm nozzle – this is not recommended as the part tolerance will be incorrect.

Supplies

Bill of Materials

  • 4 x M2 x 10mm machine head screws
  • 32 x M3 x 6 mm machine head screws
  • 8 x M3 x 10 mm machine head screws
  • 40 x M3 x 12 mm machine head screws
  • 12 x M3 x 15 mm machine head screws
  • 4 x M3 x 30 mm machine head screws
  • 3 x M3 x 40 mm machine head screws
  • 16 x M5 x 60 mm socket head bolts
  • 16 x M5 nylon lock nuts
  • 4 x M2 nuts
  • 7 x M3 nuts
  • 16 x M3 nylon lock nuts
  • 84 x M3 x 4 mm heat-set inserts
  • 6 x M2.5 x 27mm x 3mm Nylon Ball Joint
  • 2 x 25 mm x 575 mm carbon fibre tube
  • 2 x 8 mm x 600 mm carbon fibre tube
  • 2 x 2.5 mm x 130 mm carbon fibre rod
  • 1 x 2.5 mm x 100 mm carbon fibre rod
  • 1 mm x 30 mm piano or servo wire
  • 1 x 2.5 mm clevis
  • 50 ml 2-part epoxy glue
  • 500 g Polyester resin
  • 15 ml Polyester resin catalyst

Tools

  • FDM 3D printer
  • Cordless drill
  • Angle grinder or hacksaw
  • Screwdrivers and hex keys
  • Pliers
  • Soldering iron
  • Drill press or mill (optional)

Radio Controlled Equipment

  • Minimum 2 channel transmitter and receiver (for power and steering only, no reverse or auxiliary systems)
  • Brushless motor (3536 910 kv minimum)
  • brushless electronic speed controller (60 A) - with reverse recommended
  • Lithium polymer battery (4 cell upwards of 4,000 mah)

Step 1: Printing the Hull Segments

The hull consists of a left and a right pontoon. Each pontoon is made up of 6 main hull segments. 12 hull sections must be printed to make both sides of the hull. Both pontoons are identical. No supports or bed adhesion are required if parts are printed as per the part orientation shown.

Step 2: Printing the Internal Hull Parts

The inside of the hull uses a tray system to mount electronic equipment on. The trays are mounted to support brackets that also serve the purpose of providing lateral strength and ensuring alignment of the hull via carbon fibre tubes that pass through the centre holes of the supports. Supports are required for the centre hole in Hull – Tray Support.STL. No other supports or bed adhesion are required if parts are printed as per the part orientation shown.

Step 3: Printing the External Hull Parts

Each side of the hull uses two hatches to cover the access ports. The rear hatch is split into two pieces to allow fitting to the hull between the tube mounts. The rails provide a better seal once fitted. The hatches are held in place with friction fit clips. The tube mounts attach to the hull and connect the two pontoons with carbon fibre tube. Supports are required for the Hull – Tube Mount.STL and Hull – Hatch Clip.STL. No other supports or bed adhesion are required if parts are printed as per the part orientation shown. Optionally, Hull – Hatch Clip.STL (being a small part) would be appropriate to print with a smaller nozzle or on an SLA printer if available.

Step 4: Assembling the Internal Hull Parts

Before the tray supports can be installed in the hull section, M3 x 4 mm heat-set inserts must be fitted to the hull sections. These are fitted using a soldering iron. The image shows a typical install (ignoring the middle mounts).

Install the tray supports into the hull with M3 x 12 mm machine head screws.

Install M3 x 4 mm heat-set inserts into the tray mounts.

Before installing the trays onto the tray mounts, the hull must be assembled first. Start with the stern and fasten the 8 mm x 600 mm carbon fibre tube in the rearward most tray mount by drilling through the hole in the top of the tray mount and using a M3 x 10 mm self-tapping screw.

Using 2-part epoxy glue (JB Marine Weld is recommended), join each of the sections together by passing them onto 8 mm x 600 mm carbon fibre tube one by one. You will need to work quickly before the epoxy goes off.

Once all hull sections are assembled, weight can be used on the bow to apply downward pressure while the epoxy dries. Once the epoxy has dried, another M3 x 10 mm self-tapping screw can be fitted to the bow end of the 8 mm x 600 mm carbon fibre tube to secure it. The trays can now be fitted using M3 x 6 mm machine head screws as per the image.

Step 5: Assembling the External Hull Parts

It is now time to look at the external hull fittings that join each of the pontoons together. We will start by preparing the 25 mm x 575 mm carbon fibre tube. The tube must be drilled (or milled) to accept the M5 x 60 mm socket head bolts through the tube mounts. The image shows the carbon fibre tube fitted inside the tube mount while being milled.

When milling, pass M5 x 60 mm socket head bolts through the holes (1) to act as an end stop for the carbon fibre tube. Only mill the carbon fibre tube through the holes (2).

Using 2-part epoxy glue, add a thin coating to the end of the 25 mm x 575 mm carbon fibre tube.

Then slide the tube mount on to the 25 mm x 575 mm carbon fibre tube and use M5 x 60 mm socket head bolts to position it correctly. Repeat the process for the other end of the 25 mm x 575 mm carbon fibre tube and tube mount. Pay particular attention to ensure that both tube mounts are orientated correctly.

Drill the mounting faces on the hull to accept the M5 x 60 mm socket head bolts and then fasten using M5 nylon lock nuts on the inside of the hull. Tighten just enough to remove any place in the nut and bolt. Do not over tighten.

The partially assembled boat should now look like the drawing in the image above.

Step 6: Assembling the Hatch System

There are 6 indents marked on the hull sections for drilling with a 3 mm drill bit to allow the hatch clips to be installed. The hatch clips are fitted with M3 x 15 mm machine head screws and M3 nylon lock nuts. The lock nuts should be tightened enough inside the hull to provide a good friction fit when the hatches are fitted. The front hatch slides into place and then the hatch clips are rotated to hold it firmly in place.

The rear hatch must be assembled in two pieces as per the drawing in the image above so that it can fit between the tube mounts.

Optional: The hatch can be made watertight through the addition of tape or you could try using TPU filament to create a gasket-like seal.

The partially assembled boat should now look like the drawing in the image above.

Step 7: Printing the Drive Parts

The drive system consists of a motor mount, rudders and servo mount. The motor and servo mounts are designed for standard radio controlled parts. Supports are required for the two parts that make up the servo mount. No other supports or bed adhesion are required if parts are printed as per the part orientation shown.

Step 8: Assembling the Drive Parts

Fit M3 nuts to the bottom of both sides of the motor mounts (1).

Measure the centre of the rear cross brace carbon fibre tube and then position one side of the motor mount in place. Position the motor mount brace on top and use M3 x 30 mm machine head screws to loosely fasten in position. Do the same for the other side of the motor mount.

If you have your brushless motor handy, now is a good time to fit it up to ensure that the mounts are square before fastening them to the tube tightly. The motor is mounted using standard hardware (check the requirements for your motor – these parts are not included in the supplies list).

Optional: There are two cavities inside each of the sides of the motor mount parts. These are for increasing part strength by inserting carbon fibre tubes or rods (8 mm and 6 mm diameter). If using a powerful drive system, this may be required.

The motor mounts and brackets have a hole (1) centred on the carbon fibre tube. Drill these holes at 90° through the carbon fibre tube. There is no need to offset the angle of the motor mount to alter the hull’s pitch as this can be done using spacers when mounting the motor if required later on. Fit M3 nuts in the bottom of the motor mount braces and then secure the mounts through the tube using M3 x 40 mm machine head screws.

Fit both rudder mounts to the motor mount with M3 x 10 mm self-tapping screws.

The rudder linkage horns are attached to each rudder using 2-part epoxy glue. The position is not important as long as they are towards the rear of the control surfaces and symmetrical on both rudders. M2.5 x 27mm x 3mm Nylon Ball Joints are fitted using M2 x 10 mm machine head screws and M2 nuts. Both sides of the rudder are connected using 2.5 mm x 130 mm carbon fibre rod.

To secure the rudders to the rudder mounts, small hinge pins must be made. I used 1 mm servo linkage wire to create a small pin that is held in place with a 90° bend. You can use whatever you have on hand. A small amount of hot glue at the top of the pin prevents them from vibrating out.

Insert M3 x 4 mm heat-set inserts using a soldering iron into the holes (1) in the bottom of the servo mount.

Position the servo mount at an appropriate position on the carbon fibre tube to suit your servo and control linkage hardware (not included in bill of materials). A recommended position is shown in an image above.

Optional: If required, a hole can be drilled through the servo mount hole (1) and carbon fibre tube to provide increased mounting strength using a M3 x 40 mm machine head screw and an M3 nut.

The servo mount suits a standard sized servo. A waterproof servo is recommended as the position is exposed to water. Fit your servo using the included mounting hardware (not included in list of supplies). The image above shows the rudder linkage in place. The rudder spacer is fitted by drilling a 3 mm hole in the rudder and using control horn hardware to secure it. The control horns from servo to rudder are connected by a 2.5 mm x 100 mm carbon fibre rod secured with two-part epoxy glue to the 2.5 mm clevises.

This is the end of this build guide and your boat should like the drawing in the image above. Well done if you made it this far! Especially if you built one - don't forget to share. If you have any comments or questions, let me know! If you get stuck anywhere along the way let me know, or check out the series of build videos on the Electrosync YouTube channel.