Needz MOAR boat? U can haz 4/3 moar here: https://www.thingiverse.com/thing:5884064
Note I am seeing copies of my design being posted by other users in violation of site TOS - I am the original creator of this project. To assist IP enforcement investigations I will state here that these are the only valid user profiles for my models Thingiverse (N7_Cat), Printables (@N7Cat_391993) , Makerworld (@N7_Cat), and (@GLB_N7_Cat). If you are one of the thieves please get faq from the relevant TOS, if you don't want to read the faq or TOS I'm sure myself and the community will help you find the faq out
Features:
- High stability / high speed hull – multiple revisions have arrived at a hull that gets on plane quickly and can execute full speed turns even when powered by a 750W 2216. Hull is a mashup of rigger (stability), ground effect (compensates for forward weight bias) and double concave (planing and laminar flow to pump) design concepts.
- Two stage impeller (mixed flow (higher pressure / lower velocity) transitioning into axial flow (lower pressure/higher velocity)). Excellent hole shot acceleration and zero priming issues
- High strength design with reinforcement rods, ball bearings and embedded nuts
- Modular motor mount with multiple motor options
- Generic 2212 w/ 30 Amp ESC 1400KV to 2000KV (inexpensive out-runner, caturday trawling)
- 2240 w/ Shark water cooled 40 Amp ESC (water cooled in-runner, slightly faster than 2212, lower torque relative to out-runners)
- Generic 2217 2300KV w/ Shark water cooled 40 Amp ESC (inexpensive, quite fast out-runner with good torque)
- Sunnysky 2216 2600KV w/ Shark water cooled 60 Amp ESC >^.^< (expensive, fastest out-runner so far, catnip kitteh fast)
- Ability to utilize water cooling and self-bilging
- Effective forced air cooling for out-runner type motors via associated cooling impellers
- Large hinged access hatch for battery and esc, strong magnetic latching
- Variable trim ride plate
Limitations:
- A long narrow hull design chosen for hydrodynamic efficiency limits internal volume
- Print settings should follow guidelines below in order to keep displacement low
- Electronics must be waterproofed before use (Josh at Flite Test did a good vid about various methods to waterproof RC electronics with Peter Sripol (Flite Test | Waterproofing Electronics))
- Must use extensive post processing for waterproofing. Due to the way FDM walls interface with fill there is capillary action between the individual lines of printed material at the base of the sponsons and especially at any exposed openings for embedded nuts. This causes water to slowly seep into the model. I've read that brushing in melted candle wax (Paraffin @ above 37 deg C / 99 deg F) can seal a 3d print. If you do use wax keep fire safety in mind as some FDM plastics are flammable and wax has now made it even more flammable. Another method that I've seen RC airplane makers use for waterproofing is to coat external surfaces in a very thin layer of gorilla glue applied by rubbing on with nitrile gloves. The layer must be very thin otherwise it will bubble up. On the more expensive / specialized handling side RC modellers will sometimes coat boats with polyester or epoxy resins - the fumes and resins require appropriate ventilation and ppe. I tried System Three epoxy resin clear coat recently and it gives ok results with multiple light coats. I've also read that it is possible to get a print to be water tight straight off the printer but that requires larger nozzle diameters than this design will allow for (too heavy).
BOM:
- Motor Options:
- 2212 https://www.aliexpress.com/item/32672300112.html or https://www.aliexpress.com/item/1904754775.html, the gateway motor, something between a 1400 KV and 2000 KV might be good.
- 2216 https://sunnyskyusa.com/collections/x-v3-motors/products/sunnysky-x2216 Sunnysky 2216 motor, going to test a 1400 or 2600 KV motor soon - these angreh little kittehs push over 750 W of power from a ~70g package >o.o< really impressive performance - no gps telemetry yet for speeds but this is by far the fastest option - paired mine with a 60 amp ZTW shark esc
- 2217 https://www.aliexpress.com/item/2255800146800490.html I used a 2300 KV motor combined with a water cooled esc and the direct vent boat body + cooling impeller for the pond pictures featured
- 2440 water cooling motor ZTW https://www.aliexpress.com/item/4000425168430.html, note you will need to use water cooling version of the stator / cover and verify it is supplying enough cooling water to the motor and ESC. KVs (4500) on suggested motor might be high for the size of the impellers. I am not sure if all 2440s and water cooling sleeves are built to similar dimensions but you might want to substitute with a lower KV motor if you have one
- you can also design your own mount using the custom motor plate template step file (Dimensions center to center between the 3 mm mounting holes are 49 mm X 23.41 mm. The top surface of the mounting plate (measured from the large flat area not the post) is 18.738 mm below the center-line of the propeller axis). Keep weight and cooling considerations in mind if using an alternate
- Prop: https://www.aliexpress.com/item/32714017489.html
- If 2212 Motor L10 Shaft 3.18 mm (motor) Cardan
- if 2216 Motor L10 Shaft 5.00 mm (motor) Cardan - still testing
- if 2217 Motor L10 Shaft 4.00 mm (motor) Cardan
- If 2440 Motor L15 Shaft 2.3 mm (motor) Cardan
- ESC: Water proof ESC appropriately rated for your motor
- Servo: Waterproof 9g servo https://www.aliexpress.com/item/1005002219839349.html
- Reinforcement: 6 mm OD 4 mm ID Carbon Fiber Rods https://www.aliexpress.com/item/32310771446.html
- Power Source (btw if, like me, you are inexperienced with RC make sure to inform yourself about some of the precautions needed with lithium based batteries especially around charging and storage. Unlike your consumer electronics the LiPo cell is very much exposed in RC and special care must be taken. RC Review and FliteTest do some good youtube vids on the matter) :
- Cat Grumpiness
- 3S LiPo power pack (I was able to find a 1300 mAh one that fits well and can be removed via hatch 3S 1300 mAh 60C LiPo 75 X 34 X 24 mm) - The maximum extents of a battery able fit in the front of the boat are 82 X 36 X 26 mm; note this value has changed since 8/12/2021 update as motor mount moved so a bigger battery might fit
- 18650 batteries are no longer being supported, battery compartments are left in but I've come to the conclusion that its just not a good idea..I originally thought it would be cheaper owing to relatively inexpensive cells and BMS modules but once you add a constant current power supply for charging, nickle strip welder, and discharge rate / weight / C.G considerations LiPo starts to make a lot more sense...never mind the potential effects of water on Li Ion cells...
- Receiver and transmitter: Up to you (and your local regulations), I'm using a Flysky FS-i6X transmitter and FS-GR3E Waterproof receiver (note i6X will need to be in AFHDS mode to work with FS-GR3E)
- M3 X 6 X 5.3 Embedded Nuts (old link no longer works - possible substitution M3 X D5 X L6) https://www.aliexpress.com/item/4000232858343.html (also if using 2216 or 2217 some 3mm high nuts are needed)
- M3 Machine Screws (Button head and Flat head) https://www.aliexpress.com/item/32798146322.html or stainless https://www.aliexpress.com/item/32934186482.html
- XT60 connectors, 3.5 mm bullet connectors, grease (marine), filament material compatible glue. The connectors are sold by the same storefront as much of the material above.
- Sound system: Bongo Cats
Tentative Print Settings (Cura has a setting under Travel called combing mode which helps reduce stringing in the inaccessible interior). Personally I'm printing in PETG but ABS or ASA might be a good options too if you are setup for that with enclosure and ventilated space (due to easier gluing / reduced density - if using ABS or ASA I would advise against acetone smoothing as thin walls will likely deform). I excluded PLA as it is not as temperature / weather / UV resistant as the above materials and will swell / deteriorate in water unless waterproofed. I print at between 30 mm/s (TPU) and 50 mm/s (PETG) but it might still print well at higher default speeds. Thrust vector nozzle, stator bowl, and 2212 cooling impeller will be printed in TPU for its reliable layer adhesion as these components will be subject to cyclic loading and high shear stress - I've tested the 2212 cooling impeller in PETG as well. STL files are already saved in as print orientation.
*Note I've noticed that upon updating Cura that support generation varies between versions so you may need to tweak support overhang angles from posted values below - make sure to do a preview to check for proper support and alter as needed - values below updated for Cura 4.10.0
PETG/ABS/ASA Parts
Boaty (PETG/ABS/ASA): 0.4mm nozzle, 0.16mm layer height, 1 walls, 5 bottom layers, 5 top layers, 16% grid infill, supports on overhangs over 70% touching buildplate (apx 116 grams)
McBoatface (PETG/ABS/ASA): 0.4mm nozzle, 0.16mm layer height, 1 walls, 5 bottom layers, 5 top layers, 16 % grid infill, supports on overhangs over 78% touching buildplate, brims are helpful for ensuring support adhesion (apx 218 grams)
Cover: (PETG/ABS/ASA) 0.4mm nozzle, 0.16mm layer height, 1 walls, 3 bottom layers, 3 top layers, 16% grid infill, supports on overhangs over 60% touching buildplate
Motor Mount (PETG/ABS/ASA): 0.4mm nozzle, 0.16mm layer height, 5 walls, 3 bottom layers, 3 top layers, 25% grid infill, supports on overhangs over 70% touching buildplate (note the advanced option "Enable Support Interface" in cura 4.10 creates a fairly dense support structure that can be a challenge to remove - you may wish to disable for this part), brims are helpful for preventing warping (apx 30 grams)
Ride Plate: (PETG/ABS/ASA) 0.4mm nozzle, 0.16mm layer height, 5 walls, 3 bottom layers, 3 top layers, 25% grid infill, supports on overhangs over 70% touching buildplate (apx 6 grams)
Servo Hatch: (PETG/ABS/ASA) 0.4mm nozzle, 0.16mm layer height, 4 walls, 100% infill, supports on overhangs over 70% touching buildplate, brim (apx 2 grams)
Stator Bowl (Axial): 0.4mm nozzle, 0.16mm layer height, 3 walls, 3 bottom layers, 3 top layers, 25% cubic subdivision infill, supports on overhangs over 70% touching buildplate (apx 24 grams)
Stage 1 / 2 Impeller / Mid Stator / (Cooling Impeller): (PETG/(NYLON might be a good option too)) 0.4mm nozzle, 0.06mm layer height, 3 walls, 100% infill, supports on overhangs over 50% touching buildplate, brim. Note caution is warranted with the cooling impellers - the layer adhesion issues inherit to 3d prints makes it possible for the impellers to fracture under load. Wear eye protection and be mindful of risk when using
TPU parts
Thrust Vector Nozzle (Open): (TPU) 0.4mm nozzle, 0.16mm layer height, 3 walls, 3 bottom layers, 3 top layers, 25% cubic subdivision infill, supports on overhangs over 70% touching buildplate (apx 15 grams)
Stator Bowl Gasket: (TPU) Solid
N7_Cat
