How make a surfboard fin using loft?
@Anonymous, here are a couple of posts that discuss modeling a surfboard fin, some good info in them:
Jeff Strater
Engineering Director
Accepted solution
Here is one way to do it, (without the mounting portion)
From your file, took full size measurements before
Deleting the two scale features, (they are a pain)
Calibrated the canvass to full size.
Edited the canvass to be placed on the origin. (Top front of the mount)
Traced the fin profile with a spline front and back. Sketch 1
After some calculations, developed the base fin airfoil, with a top and (mirrored) bottom 4 point spline, with constraints to the handles. Sketch 2
Sweep with Guide Rail, the Airfoil, on the Trailing Edge as the Path, and Leading Edge as Guide Rail. Distance at 0.999, cause full length and your leading edge cause a fail.
After that constructed the sketches to patch Loft the tip section, in half to allow a successful Loft, mirrored.
Boundary Fill the Tip as a Join to the main fin. There is a seam, but not very noticeable, and should buff out.
Happy to help further if needed,
Accepted solution
I currently have little time but thanks to @davebYYPCU I had a strong base to work with.
The proper way to loft this is by creating a helper surface. This is what I do in the first step in the screencast.
The loft profile is tangent at the leading edge. To maintain that tangency along the leading edge of the loft, a sketch is not enough. Tangency can only be defined to another surface and that is the only purpose of that helper surface.
I define that tangency when I change the setting of the forst rail from "connected" to "tangency G1".
That allows me to create the compete half of the shape in a single loft.
Let me clarify the term "proper". For the purpose of this project @davebYYPCU's method is also perfectly acceptable!
Laterale sketch is bad. Line is not attached to origin.
Tangent handles here must be vertical,
Then no error.
might help.....
I have done many tests but I continue to have problems.
unfortunately editing the loft that I am copying however it is not clear if the profiles are the split lines or a point while for the guide it is clearer.
I am attaching my file again so if you want you can check if I have correctly set the vertical handles and if you can maybe kindly indicate precisely profile 1 profile 2 and the rails so I will try again. thank you very much
Laterale Sketch still bad,
straight line must be horizontal.
Profile is not touching Rail 2. Everything else is OK.
When making the loft, profile and pick spline point, hide sketch, use body edge rails off the extruded body.
When you fix Laterale sketch, extruded body will update.
For Loft, must be accurate sketches.
Might help.
Hello @TrippyLighting / @jeff_strater
I watched your tutorial and found it helpful, thank you for that. I am trying to make a fin in a similar manner but need a 0.025" flat on the trailing edge. To do this I am using a profile at the tip of the fin that has this flat edge (instead of just using a point as you did).
Something about the spline I drew for the trailing edge rail is generating extra edges when I loft between the two profiles. I have spent several hours trying to fix it and draw it in different ways, nothing is making it work.
Would you please take a look at my file and see if you can suggest how to draw the spline so that I don't get the extra trailing edge edges?
Thank you so much!
Here is how I am currently drawing the rails
and the unwanted edges I am getting
also here is the profile at the tip and the profile at the root. The flat on both profiles is the same 0.025"
