Two fin prototypes: finished

General Discussion
1

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Two prototypes built with some experimental finfoil g-code.

First time running a two sided CNC cut.

More at (story with videos): https://www.instagram.com/finfoil/

 

More explanations and build pics following next week!

2

Looking good Hans!

I have been using third-party milling/CAM software for many years.

Now I am beginning to really like intergrated CAD/CAM like Fusion360 for at home or Inventor+HMS at work.

Having this intergration will be awesome for finFoil.

Regards, J

3

The main reason I developed this g-code generation is that I felt the gcode could be generated more optimally and better suited for fin production.

finfoil generates standard g-code, and does not do any machine control. So it can be used with any 3-axis CNC machine.

For double sided machining, I’ve put some machine pauses in, so you can fully run the program without having to interact with the controlling PC, just by resuming the machine when paused (e.g. when the material needs to be flipped).

Also no tool changes are required, finishing is best done with the same large diameter bit as used for roughing.

Apart from material alignment (only for double sided machining), the process is very simple and fast.

4

Time for some vacuum bagging!

The big one gets 1 layer 300g/m2 carbon and one layer 165g/m2 e-glass (~6oz I believe).

The small one gets 3 layers of 165g/m2 e-glass.

 

For the carbon one, the glass layers serves mostly as a scratch protection layer.

 

The big fin is meant as a shallow water slalom fin with a high speed low angle of attack foil profile, a bigger brother of: https://www.swaylocks.com/forums/shallow-water-fin-design-build-ride-report

The small fin is an early planing freestyle fin, with a foil profile selected for low speed and high angle of attack.

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5

That looks awesome!

Would you know if there s a way to have fin CNC-milled professionally, without risking theft of the file? 

A solid carbon plate as core, with wood laminates on both sides would look awesome on tubercled fins.

 

6

Hey Mik,

This is a tough one, basically the same struggle with any sort of software-based intellectuall property… Either you have to:

  1. Trust the machinist not to distribute the file,

  2. Have lawyers on both sides draw up and sign a non-discolsure agreement than can be enforced, or

  3. Generate the CAM (CNC file) yourself, hand-carry the file to the machine, load the file on their machine yourself,be there duing the run, and make sure all working copies are deleted and then permantly deleted from the machine. If you don’t know how to run the machine’s file system this becomes difficult to impossible, forcing you back to #1 or #2.

Best to find someone you can really trust.

 

7

Hans

cool.

You drilling holes through the bulk piece for location when you flip?

 

8

I agree. Once it’s GCode there is almost nothing you can do to secure them.

Design files you can protect somewhat, but cutting files nup.

9

Thanks, jrandy, that is just what I expected. 

 

10

That’s a possiblility, but not the way I did it.

I machined a ridge along the Y-axis in my wasteboard, to align my fixed width piece against, and then I marked the center of the bottom edge on the wasteboard.

You can then flip against the ridge and align again to the center mark.

 

You can find more details on instagram: https://www.instagram.com/finfoil/

 

But any strategy can be implemented.

11

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12

 

You could generate g-code files that are impractical to use in a mass production setup.

e.g, where you need to hand finish (some parts of) the fin, it’s quite hard to add these finishing passes without the 3D model or .foil file.

Or make the gcode slow by using a small step-down, however it is easier to remove gcode than it is to add gcode, but still it requires effort.

 

Although it does not fully protect your design from stealing, it already takes away some possibilities for production.

With the .foil file anything is possible.

With the STL file, you can produce but you can’t edit.

With the gcode, you can produce, but only with the same machine tools and settings, which is more restricive than the above.

 

Anyway, you should not try to protect it more than it takes to just redrawing the fin. Because that is the competing option to steal your design.

13

I know you must have already mentioned it in this thread or another one, but where (or how) did you get those fin base molds? 

14

These are just finboxes bought from https://chinook-leucate.com/

However it requires quite some sanding afterwards to loosen the fit as the surfaces are not perfectly flat.

I need to find some time to build me some proper molds, this video shows one way of making a mold: https://www.youtube.com/watch?v=5JCCBHW646k

15

Thanks Hans, I almost missed your reply, just found it now by accident.

Most helpful! 

16

Thanks. Flipping accurately is a tricky thing in this sort of CNC work,