Order of operations 3d printed airfoil with internal structure

[MichelKesin]

I am trying to design a 3d printed rudder blade for my sailboat. It would be a hollow foil shape that fits over an aluminum plate. My intention is to fill it with resin and do some fairing on the outer surface. I want the walls to be 1-2 layers thick with some internal structure to help center it and maintain its shape until the resin cures. It will be way too big for my printer so I plan to print it in chunks and glue it together the same way they do with 3d printed RC planes.

My question is how do I attack the order of operations? Do I extrude a solid foil and hollow it out? Do I extrude a thinwall shape? What's the best way to draw ribs inside hollow shell? Do I use the surface tools?

I am able to use the airfoil macros to create a foil shape but I'm not sure wha to do with the object it creates, it seems to be like a wire. Should I convert it to a b-spline? trace it onto a sketch?10.0.0.0.1 192.168.1.254


Anyway, I'm fairly inexperienced with 3d cad and especially Freecad so any advice or suggestions are appreciated. Thank you in advance.

[M4x]

Hey Michel,

welcome to the club!

This should've been (and therefore moved to) Help on using FreeCAD. Please follow that link and have a look at the big red banner on top. Afterwards, post the your FreeCAD version.

Do you have anything so far? If that's the case, a FreeCAD file would be nice. How should we think of "fairly inexperienced"? This might not be the project to start with

[chrisb]

Moved.

[Bance]

I am currently designing a VAWT, I used the air-plane design WB for the aerofoil.

It also produces a wire, just use draft to sketch to convert it then drag'n'drop into a body, then pad.

If you don't mind me saying as a an ocean sailor of many thousands of miles of passage making in my log, I wouldn't set foot in a boat with a 3D printed rudder, no matter how much resin you poured in it!

[hammax]

... I already printed such a rudder for a RG65.
Start on a base plate, which will be worked to shape or removed.
The problem is to get the trailing edge smooth enough.
And the printable form of the tip.
https://www.forum.rg-65.de/viewtopic.php?p=25117#p25117
https://www.forum.rg-65.de/viewtopic.php?p=29546#p29546

3DPrintRudder.PNG (29.42 KiB) Viewed 1058 times

[GeneFC]

I wouldn't set foot in a boat with a 3D printed rudder, no matter how much resin you poured in it!

I think there may be a slight difference in scale under discussion here. You would have a hard time setting foot in any of these boats.

Gene

[Bance]

The OP doesn't mention scale at all, except to say it would be far too large for the bed of a 3D printer

[cadcam]

It would be useful to know

1) the scale of the rudder (If using a resin fill with thin walls it
can lead to distortion if there is any heat generated (exothermic)

2) Is there any limitation on the mean density of the rudder, if yes
What overal density and of plate, resin 3d printing material

3) If using FDM what material are you planning to print in and
what adhesive are you planning

4) What surface finish are you hoping for, e.g. if using ABS
then issues may be different to PET

5) What stiffness is required in the primary directions

6) Given (5) does the center plate have to be one single thickness
e.g. does the stiffness have to be generated by the 3D Printed material + plate + resin or
can there be shape in the plate

Best Wishes

[Vincent B]

It should be logical to start from the shape I mean the surface of the rudder, then build the structure.

[hammax]

... is scale really a no go argument for future development?
A big gantry like 3D mini printers and something like LW-PLA, afterwards cladding inside and outside with a CFK/GFK shell.
Sandwich from scaled up 3D printing.
No more lamination forms, light weight and built in the first run => all the features you like in 3D printing.
https://www.forum.rg-65.de/viewtopic.php?p=29941#p29941
https://www.forum.rg-65.de/viewtopic.php?p=29790#p29790