3D printed Jetsprint jet boat V1

Link for version 2 is in description

Maker/DIY

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Description

VERSION 2 IS OUT: https://www.youmagine.com/designs/prototye-3d-printed-jetsprint-jet-boat-v2

Forum thread: https://www.rcgroups.com/forums/showthread.php?3061106

A personal project I've been working on. Posting here since there aren't many 3D printed jetboat designs out there.

lijingwei made one too. He's also made some improvements. You can find these here: https://www.thingiverse.com/thing:2890756/remixes

My boat's maiden outing:

Specs:

  • Impeller: 29mm with 29mm pitch (18-29mm pitch files included)
  • Nozzle: 22mm
  • Hull length: 430mm
  • Hull width: ~165mm
  • 9g servo for steering
  • mounting points for optional reverse bucket and servo
  • Assembled mass: 1308kg

Power system:

  • 3674 brushless inrunner motor @1900KV. 61A max. Max power 1800w.
  • 2x 2200mAh batteries, 25C.
  • 120A watercooled ESC

Credit for the included axial jet drive calculation spreadsheet, goes to RCgroups member UnusualRC. UPDATE: I've been notified there is a mistake in one of the formulas on the sheet. Please be aware of that.

TODO:

  • Get video of it at top speed with CoG moved foward running at 6S then retest

DONE:

  • Test boat with 6S configuration. boat is way overpowered which is great fun. SO fast. Gets a lot of air.

IN PROGRESS

  • Make next version with bigger hull - calculations were incorrect and hull sat far deeper in the water than calculations indicated

  • Improve lid to be more water tight on next version.

Other side notes:

  • batteries, esc and motor all stayed stone cold in 3S mode running at full speed. Motor is wayyy oversized for this boat.

  • It nowhere near uses the full power available to it running at 3S.

Materials and methods

I printed my hull at 0.3mm layers with 3 perimeters and 25% infill with support structures enabled. The hull is best printed in PETG or ABS for durability. I've printed my impeller in PLA because of how it is easier to get a very clean print when using support material. I find it prints best at 0.15mm so highly recommend that.

The impeller is intended to be glued onto your 3mm drive shaft. Its recommended that you sand the shaft lightly before gluing to ensure a good bond.

The nozzle takes a 3mm inner, 4mm outer diameter teflon tube as a bushing for the shaft (check the last two pictures above). I cut 5mm off my bowden tube and used this. Teflon is a very durable and low friction material - perfect for use here.

Bill of Materials:
- ~430g of filament
- M3 misc screws
- self tapping screws
- 1x 100mm long, 3mm stainless steel rod as driveshaft.
- 1x 623RS bearing (623ZZ is also fine but rubber seal is of course better when water is involved)
- 1x 750mm of servo pushrod wire
- 1x flexible coupler to go from motor to the driveshaft. I used 3 to 5mm adapter. Most 36mm diameter motors use 5mm shafts. I would recommend a universal joint which can be found for $1-2 on aliexpress. You could print your own universal joint or direct coupler (both are printable and included in files).

Electronics:
- 2x 9g servos (1x if you don't opt for the reversing bucket)

- 1x Motor + ESC
I'll be using this motor: https://hobbyking.com/en_us/turnigy-xk3674-1900kv-brushless-inrunner.html
And this ESC: https://hobbyking.com/en_us/hobbyking-120a-boat-esc-4a-ubec.html

You'll want to pick a motor/battery combo that delivers up to 20,000 rpm and can handle about ~75A continuous. Refer to: https://www.kehrer-modellbau.de/en/kmb-jet28/jet-drives/kmb-jet28-rev.-3-with-short-steering-nozzle

Included in the files are mounting brackets for 36mm and 28mm diameter inrunner motors as well as a mount for common airplane motors using 19mm hole spacing. If you need a bracket for a different motor, let me know the dimensions and I'll make one up for you.

- 2x lipo batteries. You'll want two: one to place in either side of the motor for balance. I will use 2x 2200mAh 3S lipo batteries. I like to use velcro to hold batteries in place.
- 1x transmitter/receiver set. I will be using my Flysky i6 transmitter with receiver

If you have any questions, please do ask. As noted at the top of the page with a link, there is now an improved new version published.

Documents

Issues

Issues are used to track todos, bugs or requests. To get started, you could create an issue.

Comments

957ee66a7df9ed22748e32e2717b2b3d?default=blank&size=40kblman added this to the Toys collection ago
330e735e74ec9f0dd00d9e78d7a27582?default=blank&size=40maxxxmax added this to the RC boats collection ago
08a198a96c54b92dfcdf8ee6f180ec81?default=blank&size=40T J added this to the boat collection ago
Bb75da4d7e6f900f5f6d759169083cb1?default=blank&size=40Jotham B published this design ago
Bb75da4d7e6f900f5f6d759169083cb1?default=blank&size=40Jotham B commented ago

I recommend using ABS slurry to join the parts if you printed them in ABS.

ABS slurry is made by dissolving ABS filament in acetone.

If you're using PLA, superglue works very well. A good superglue will bond the parts no problems. I find if you use a 'kicker' (its a glue activator) it joins even stronger.

915068c3af9303e0222d15db1303ea33?default=blank&size=40MOD commented ago

HI

Have printed 2/3 of hull and it is looking nice. (Congatulations) Just wondering how the sections are best joined together.

Ac93326d8d3bea271240d149ce0d8dc6?default=blank&size=40lijingwei added this to the boat collection ago
Bb75da4d7e6f900f5f6d759169083cb1?default=blank&size=40Jotham B commented ago

@BeniniD, I've uploaded a version that has a thicker eyelet and thicker walls everywhere. Hope this helps.

70521441bafb9beb8458f54ac57e31d9?default=blank&size=40BeniniD commented ago

thank you

I have a bit of trouble printing the external propulsion unit.

the semi sphere is very thin, and with abs it is fragile.

I advise you to enlarge the walls externally and reinforce the eyelets.

today I try a petg print,

I update you!

grazie

ho un po di problemi a stampare il gruppo esterno di propulsione .

la semi sfera Γ¨ molto sottile , e con abs risulta fragile .

ti consiglio di ingrossare esternamente le pareti e rinforzare gli occhielli .

oggi provo una stampa in petg ,

ti aggiorno!

Bb75da4d7e6f900f5f6d759169083cb1?default=blank&size=40Jotham B commented ago

Thanks! Yes I've just uploaded the STL file for the lid. It doesn't seal very well but it should be ok if you use a soft foam strip. The next version of the design will have a much better lid since this the surface is flat. It is much easier to design a lid for it: https://i.imgur.com/QHB7cP0.png

I haven't made much progress on it lately since university has been really busy and other things have been soaking up a lot of time. If you ever want any other files just let me know and I'll upload them :-)

I look forward to seeing your boat go!

70521441bafb9beb8458f54ac57e31d9?default=blank&size=40BeniniD commented ago

hello Jotham B

I wanted to compliment you on the project.

I'm printing the hull, aware of the problems you've encountered.

would you load the lid file, so over the weekend I mold it and go to the lake to test it?

thank you so much !

F20eba832960c5f28628893f341e5d31?default=blank&size=40ThomasDbg added this to the RC Schiffe collection ago