Issue with stitching body

[danotranto]

I have this guitar body made from lofting. I had patched and stitched the body and it only shows one body in the menu, but it is behaving like there are more than one and that the stitch did not work (in section analysis the body is still just 2d surfaces).

Also any tips on how to loft things like this would be greatly appreciated!

[jeff_strater]

I don't have time right now to dig into the design, but the Stitch command itself shows where the problems are.  You have one on each end of the body.

On the neck end:

zooming in:

On the other end, same thing:

again, zooming in:

so, find the features that caused those openings.  If you can identify which specific feature caused this, it will help others to help you.

[davebYYPCU]

Easy to find, Jeff, Sketch 4 is not connected to the other sketches and is wide open, the loft shrinkwrapping has opened the gap.

Mmmm.

I don't understand the extrudes / Patches that were deleted.

Might help....

[danotranto]

Hi,

Thank you for taking a look at that.

I have attempted to redo the entire file (geometry was too weird to patch in those two small gaps), and this time I can't figure out what is causing this loft on the right side to fail (it will not loft to the profile on the Y axis, it only lofts "flat" to the centerline when I select the curved face of the other side to be the last portion of the loft. 

How do I go about trouble shooting lofts made with splines?

[danotranto]

I was able to create one half of the loft by creating two ruled surfaces.  I then delete the ruled surface in the middle and try to create the loft on the other side but it doesn't recognize the loft edge in the center.

[davebYYPCU]

If you Delete the Ruled surface, you also delete the 1st Loft.  Use Remove, or just hide it.

You made a ruled surface to avoid using the sketch, so hide the sketches for 2nd Loft.

you have Rails? Connecting to the Centre Datum Line by the look of it, only one vertical Rail sketch?  You have a Outline Surface on that side too, right?

Might help....

[TrippyLighting]

@danotranto I personally would probably try to build this with T-Splines, not with surfacing techniques. Trying to create both halves of the top surface as 2 lofts is not going to work well.

If  you would build this with solid modeling, you'd first create a base body and then fillet it.

This would be a similar case.

I would first create the main surface then trim it and create another loft or a series of lofts for the "fillet". trying to loft surfaces with such large changes in curvature in one go is usually not going to result in good surfaces.

The spline end points in this sketch are not coincident. That is never a good idea!

[danotranto]

Hi,

Yes, I deleted that section of the sketch redid it so it is one continuous spline until the top area. I was able to get that side to loft correctly after that.

I had this working and decided I wanted to add more rails, I deleted the lofts I had made, went back and made a construction plane and new sketch for a rail further up the body.  Now it will not loft even though I have not changed the ruled edges or anything with the sketches that had been used to make the initial loft. I cannot make heads or tails out of what makes lofts succeed or fail.

Unfortunately,  the shape of this body is too complex to use fillets and requires splines.

[davebYYPCU]

I cannot make heads or tails out of what makes lofts succeed or fail.

Without the current version of the file we can't assist you.

In my earlier post the vertical centre line sketch did not connect, and lofting to a point there is not recommended.

The current photo shows the ruled surface and the sketch at the same location, you should use body edge and not sketches in that area, leaving both visible, gives Fusion the option to select the wrong one.  Hide the clutter.

 too complex to use fillets and requires (splines) T-splines.

This Loft is asking too much of Fusion, I would likely get it with 3 Lofts for the whole job, flattish top patch, and use loft for the fillet like boundary.

Might help.....

[TrippyLighting · Accepted solution]

---

r@danotranto wrote:

...the shape of this body is too complex to use fillets and requires splines.

---

You misunderstood what I was trying to convey! The main  issue here is that this is going to be more than one loft. The curvature changes in this loft are too large to be able to sufficiently control the shape with more rails. Most of the time that is only going to make it worse. 

Your initial halves create a loft that has singularities on both ends. That is not desirable either.

[danotranto]

Ok, I got the loft to work when suppressing other sketches....weird. I don't think they were connected to the loft...

Probably have to scrap attempting this with lofting in surface and learn T-Splines/Mesh I suppose. 

How would I go about splitting this shape up into multiple lofts?

[danotranto]

delete

[TrippyLighting]

Don't delete posts 😉

I'll see what I can do tomorrow to create a screencast, but it'll be later in the day.

You picked a difficult shape so some frustrations are to be expected.