I’ve been messing around with the 3d printer and achieved what I think is a good result on my rudder.
I printed a two part mould (is it “mould” or “Mold”) and used that to create a FG rudder with a balsa core and a profile that is extremely close - if not identical other than surface finishing issues - to the CAD version.
So it’s time to scale up and look at the keelfin.
My immediate issues arethe need for at least 2 pieces per half, an extremely long print time at relatively high quality and will necessitate me aligning the pieces with possible joint issues . These were non-issues on the rudder, and non of them are insurmountable but it got me thinking of alternative methods to use the printer more economically. So I have a hair-brained idea that I’d like some input on.
If you build a version that has the carbon rod placed between two sheets of Carbon/FG then you get a very good keelfin but not much control over the foil shape.
So what happens if you take the carbon tube, and do it like the guys make plane wings?
This has the bonus of the carbon rod for strength but also gives me a nice long tube to align the bits of printed frame.
Then skin this skeleton.
Here is my basic idea. The framework would need to be cut into two sections per half to fit on the 3d printer build plate, so these pics are what one half of the completed keelfin frame would look like.
That structure is 2mm thick for the vertical walls which is pretty good. In the Slicer software it estimates 4g for that entire half (which excludes the weight of the carbon rod)
So total on the 3d print will be in the region of 10g assuming that my choice of framework is correct? I can make it in pretty much any way we want to try.
This is how they would have to be printed,
Ignore the settings on there
Would you put more vertical struts at the front, back, more foils at the lower region by the bulb - Educated guesses would be most welcome
I’m wondering about two carbon rods?
How do you then go about skinning that?
Possibly thin balsa which then gets FG/Carbon (I’ts actually quite a nice idea for boats wanting a very exact shape with a wooden finish on the keel?)
Fill with styrofoam, sand, skin using Claudio’s clamped foam method?
It will need traditional finishing work but at least the foil shape should be quite exact.
I’m going to give it a bash but if you guys can see/think of any pitfalls I’m missing or possibly better methods let me know.