Sketching around a mesh body or mesh sketch section.

[Anonymous]

Apologies if this is covered already, but I cant find it if it is. Brand new Fusion 360 user transitioning from Tinkercad. So far I've only twice gotten frustrated enough to completely uninstall Fusion before cooling off and reinstalling. 

I'm trying to design a box, that will fit around another multi sided box (specifically the main enclosure for a saitek pro flight yoke). I'm starting with a sketch. I found an stl of the saitek box, and have imported it as a mesh, then used mesh sketch section to get an outline of the shape. The way Id like it to work is that I can start a sketch, and just create lines that will snap to the lines created with the mesh section, but haven't been able to. I tried starting a sketch and just tracing the profile with new lines, zooming in until the snap grid appears to line up with the vertices I'm trying to. But I don't think that's working like I want (if you zoom in enough the points aren't really aligned). It would probably work in practice, but I am going for precision. I know there must be a function for what Im trying to do, but I cant find it. I have figured out how to turn the mesh into a brep body and that feels like possibly the right path, but I'm not sure. Ive attached some screen caps to help explain.

[TheCADWhisperer]

---

@Anonymous wrote:

...zooming in until the snap grid appears to line up with the vertices I'm trying to. But I don't think that's working like I want (if you zoom in enough the points aren't really aligned). It would probably work in practice, but I am going for precision.

---

This isn't a good way to use Fusion 360.

You will want to use parametric dimensions to precisely control your geometry.

The imported stl is basically rubbish - use only as reference geometry.

Stl takes nice smooth curves and facets everything into triangular planar faces - not good.

You want to get back to the original nice smooth curves and larger planar faces rather than faceted triangles.

File>Export and then Attach your *.f3d file here for instructions.

[Anonymous]

Thanks for the reply. I am attempting to only use the stl as reference, just to make a sketch that matches the outer dimensions of the box. Once I have that I am thinking I can use constraints to deal with the rest of my sketch while not affecting that section, then give it depth and continue my design. 

[TheCADWhisperer]

Since you didn't get very far - I have no idea of your true Design Intent, so instead I did a quick model of the actual part.  You will follow the same technique in creating your component around the part.

Play the Timeline one step at a time to see how I modeled each sketch and each feature.

Right click on each sketch and Edit Sketch and note the dimensions on the sketches - these are parametric dimensions that control the sizes - if you double click on a dimension and edit it, you can change the size of the geometry.

[Anonymous]

Thanks for this. The main design intent is 2 fold: a pair of boxes that will fit on either side of the saitek box, and nest up against it. I am going to design electronics to go inside, giving me control of the avionics in my flight sim. I fly in VR, so I cant see real physical items, and having tangible knobs to set certain things is preferable for me than using the vr contoller. I already built a simpler unit, using tinkercad, as a layoff/lockdown project (I assemble avionics for my dayjob and miss it). I detailed the project here if you are interested: https://youtu.be/dEtDt6eQK5Y

The 2nd intent was to use this time to learn Fusion, and a different design style. I can totally see the power in parametric design, but I'm struggling with the transition a bit. 

I've attached a super quick and crude mock-up (pic and an stl) I just did in tinkercad just to show what it is I'm trying to end up at, at least for this phase of the project. My goal is to have the box much nicer, and have faceplates attached to the front with the buttons and encoders attached. 

Im goign to open up your example and check it out, thanks so much for your help. 

[TheCADWhisperer · Accepted solution]

Examine the Attached.

You can edit any dimension to change sizes of existing geometry.

[Anonymous]

Thanks so much! I think by biggest stumbling block here was the initial sketch. I really wanted to just to be able to pull the dimensions from that initial stl. Once you showed me your sketch and model, I tried making one of my own, and learning a bit more about what constraints were relevant for the task at hand. 

I attached a copy of what I ended up with. After I "finished " (I'll probably do it over a few more times trying different ways to get to the end result) this I opened your last one and and it really opened my eyes.  Particularly the second sketch with just the angle that you used to slant the top. I ended up doing 2 sketches, one on the xz axis to get the angles of the saitek box, and one on the yz axis to get the slant, then push/pulling them, aligning, and shelling. 

Thanks again for your help, I've been banging my head on my desk for what feels like days and today I finally made some real progress in understanding the process.