Lowly Worm Apple Helicopter for LEGO DUPLO

My own custom design of a Lowly Worm apple helicopter for Lego Duplo.

It's not exactly "ready out of the box" but the end result is satisfying 😅

You will need the following to assemble:

• Super glue (cyanoacrylate)

• 3.2 or 3.3 mm drill bit (or a #29 drill bit in imperial units)

• M4 thread tap (or #8-32 thread tap)

• 10mm M4 countersunk screw (or 3/8" #8-32 screw)

• Small round file

For glossy finish you will need:

• 120-5000 grit wet sanding paper

• Autosol Plastic Polish

I used organic supports for the Apple_top so the Dash Board is unaffected.
I used brim for the studs.

To avoid supports on the bottom half of the apple, it’s constructed of four parts glued together: Apple_bottom, Bottom_lip, and 2 x Bottom_studs. They are glued with super glue (cyanoacrylate).

The same goes for the rotor, where the Rotor_hub is glued on the Rotor_blades.

I have uploaded prints for fixtures for glueing on the Bottom_lip and Rotor_hub to ensure exact placement.

The helicopter is designed to be assembled with a standard Duplo chassis piece as seen on the pictures.

To acheive the glossy finish, I sanded the apple with the top and bottom assembled. The first sanding with 120 grit is the most time-consuming. For the best results, it’s important to continue sanding until no shiny filament is visible. Take your time moving from 180 to 240 grit and from 240 to 320 grit to ensure all scratches from the lower grits are gone - if you move on too quickly, they will show up in the final result."
I suppose this could be done with vapor smoothing using another kind of filament and save you a lot of time.

I sanded the rotor before gluing the hub on.

The hole in the Rotor_axle needs to be drilled out using a 3.2 or 3.3 mm drill bit and tapped with an M4 thread tap. Be careful not to drill or tap all the way through!

The rotor can spin. To press it onto the axle, carefully file the small protrusions inside the hub using a small round file. File a little, then try pressing it on. Repeat this process until it fits. I pressed it on while there was still considerable resistance.

Before gluing the studs to the bottom, I sanded the conical part with 180-grit sandpaper. After gluing, I used small spring clamps to hold them in place.

The small Lowly Worm figure is a figure I purchased second-hand and modified to be compatible with Duplo by attaching a Duplo stud under its foot.

I have included both .stl and .stp files for all the parts.

Print Settings

• Printer brand:

  Prusa
  

• Printer:

  Prusa XL
  

• Rafts:

  No
  

• Supports:

  Yes
  

• Resolution:

  0.1 - 0.2
  

• Infill:

  30%
  

• Filament material:

  PETG

Let me know in the comments if anything is unclear or if you have any questions.