Finding outer point of a shape to draw tangent and perpendicular line

[dantahoua]

Hello.

I tried a lot of stuff but can't find a solution for this... Here is a drawing of a guitar arch-top. I need to draw some lines perpendicular to the center line but passing:

-one exactly through the center of the waist

-one exactly through the upper bout

-one exactly through the lower bout

Those 3 line should be perpendicular to the center line

My first idea was to draw a line parallel to the center line and make it tangent to the curve at the wraist, then another at the upper bout, then another at the lower bout. So I would have the intersection point. Doing the same on the other side, I should end with two point and be able to draw my line... Sadly I'm not able to do that! Seems pretty simple but...

I included a photoshop of the result I would like...

Anyone could help me?

Thanks.

[davebYYPCU]

Sketch Tangent constraint does not work on splines.

I think your best work around would be to align the perpendicular lines to the widest and narrowest points by comparison to the grid lines at the respective locations.

Might help....

[dantahoua]

Arf, I know, but there must be a more precise solution, no? Always amaze me how Fusion 360 is enable to make some such simple task! (like aligning object also...)

[laughingcreek]

what your asking for would be a great tool to have.  This doesn't really help, but here is an example of my approach to drawing guitar type shapes.  I did this a while back to demonstrate one way to get a pretty decent shape without a gazillion control points.  The basic idea is to put points at min/max points of curvature, and constrain the tangent handle to horizontal/vertical.  You can get just about any "classical" curve with this method.  The serendipitous result is that you now have points at the widest and narrowest points by default.

[dantahoua]

Hey thanks! I saw your video a while ago, really helpful. For now I ended up exporting the curve intoo IGS format, going to my frien who use Rhino, importing in Rhino, aligning to shape in Rhyno and exporting the DXF back to Fusion for CAM... Oufff...

Funny thing, I don't know anything to Rhino but I was able to do this in 15min...

Please Autodesk, open some common soft and watch how they do some really simple stuff (the align stuff in Illustrator is awesome)... The ending Fusion product would just be awesome with such functionalities! 🙂