Matching double-symmetric form to body

[dd.stork]

Hi, I come from a remarkable experience on other MCAD softwares but I'm fairly new to Fusion.

I have already looked for existing questions about on this topic but I can't either find a similar situation or a solved answer. And I don't know if I'm insisting on some weak spot for Fusion or just doing something wrong. But anyway I feel quite discouraged because it's an operation that I used to do in 5 minutes with my other CAD.

I have a doubly symmetric Form shape which I want to connect to an existing parametric body. The body is a solid of revolution cut on top with an extruded sketch. I need at least G1 continuity across the connection.

parts to connect

Shared design:

https://a360.co/3bhtmD9

Initially since I wasn't familiar with Form, I used a prismatic body in place of the Form, then connected using Surface Loft to the main body and closed the boundaries. Result was quite unsatisfactory since the Loft worked only setting G0 continuty on one of the profiles, it took a lot of messy workaround to be set up (3D sketches using includes) and the prismatic shape wasn't reaching my design intent.

So I watched some of the courses about working with T-splines and gave it a try. Now I have this form that I tried to manually match to the body, but a row of patches can be deleted if needed.

But could'nt find a solution.

I tried leaving a gap and connecting with Loft: almost worser than the Surface loft. Can't add a single G1 condition ("Self-intersection or bad geometry" on-canvas message)

I tried Match and it just shows some twisted curves or the message "invalid input", depends on the case (very unstable from this point of view).

Other simpler G0 connections like Pull or simple move are not acceptable for me.

Am I doing something using a bad workflow? To me it seems totally natural operation which requires some very hard and unstable operations to be done. 😲

Thank you

[davebYYPCU]

While not an expert in Tspline, 

make it as one piece in Tspline, 

Flatten a Sphere, and Alt - pull the face/s out.

Loft G1 continuity is only available from body edges. Any rails must be Tangent connections to the disc and the other end.

Might help....

[TrippyLighting]

Trying to match that T-Spline to an existing NURBS surface does not make a lot of sense. The shape you are trying to create is easy enough to do with standard surfacing techniques, or as @davebYYPCU  suggests, model the whole thing as a T-Spline.

Also, your T-Spline has triangles, which s an absolute No-No, particularly if you want to create higher-end surfaces and the N-Gons (created by T-Junctions) should also be avoided.

[laughingcreek · Accepted solution]

Just to get an approximation of the eventual form, you can cut the surfaces back a bit and loft them together.  See attached.

But ultimately this object should probably be made with surface modeling techniques. 

Also, t splines are trickier than they seem at first.  there are a lot of pitfalls to this approach. 

It helps to  model more while in "box mode".  look at your model in box mode, then look at mine.  You'll notice that mine isn't as lumpy when viewed in smooth mode.  you can tell why in box mode.

[dd.stork]

Woow! I really appreciated all the answers by all of you, but accepted this one since is the one that preserves most my intent (full control on the Form part while still retaining parametric connection to a part which is also still parametric).

But I have comments to all the other answers (this is probably to clarify further points for me):

@laughingcreek : yes, I had this feeling about how the control polygons appeared but honestly it is almost discouraged by the number of clicks needed to frequently switch visualization modes. So it looks that you used a surface loft (I tried that) but between boudaries which are quite more regular thanks to the shape used. Brillant (old boundaries were legacy geometry coming from old approaches that actually had no sense anymore)

@davebYYPCU : I thought that was the very last solution to try. Mainly because (probably coming from years of parametric modeling) I am unconfortable when knowing that I have to adjust/redo something in case I need to make even a slight change to what is the main feature of the entire design. BTW: G1/G2 continuity was actually available on both ends since I am selecting directly the edge of the surface converted from the Form feature (No 3d Sketch).  But then it failed to generate the loft.

@TrippyLighting : I actually found trickier to use standard surfacing techinques because I'm still in the conversion phase from a CAD where 90% of the work is made by construction geometry, I find it quite different from Fusion approach but still want learn the Fusion way. But I wanted to explore the use of Form and its practical applications before trying to do an approach that I already "know" (perhaps a Loft between two arcs for the front face and then one extrusion for the top). 

Thanks everyone, very appreciated