Surface Mastery Part 10 - How To Preserve Shapes When Patching Surfaces | How To Use Loft and Patch

In this video we are going to again talk about Loft and Patch. This is a common problem figuring out when to use the right tool. In this video we are going to talk about filling in surfaces when preserving geometry and dealing with non-ideal openings. This comes after a great comment on the last video about some general rules when using Loft vs. Patch.
If you want to follow along here is the dataset: a360.co/3vjiikN

[@kubo527]

Definitely the best CAD channel on KZbin! There are no words to describe it!💓

[@LearnEverythingAboutDesign]

Wow thank you!!!

[@bwilliams1815]

Usually I cut a cleaner 4 side shape outside then loft but seeing other issues and ideas always makes me think. Thanks for the example and insight.

[@LearnEverythingAboutDesign]

You bet!

[@DanteEhome]

The instinct of me solving the problem is cut the comlicated shape into smaller easier ones. But you explained the weight very well,and I kinda understand that it's not gonna be perfect.

[@PiecesOfPrestige]

If you turn the shape into a solid by patching the openings, then use the solid tool Delete Face, often, the solid will fix itself to become the shape it was previously (granted, sometimes it will deny the deletion). Worked for me when designing a rc plane and having timeline turned off only to recognize I've cut a shape out in the wrong spot (finally learned to just turn direct modelling off lol, oh well)

[@LearnEverythingAboutDesign]

Yeah the Delete tool can be great! Fusion does a pretty good job of patching geometry, but what it does is extends the geometry, it won't revert back to an old shape (to the best of my knowledge). So for example if you delete a fillet it just extends the faces until they intersect at a corner. I have had it do weird things before with true circular objects. Have you noticed it actually going back to an older shape?

[@PiecesOfPrestige]

@@LearnEverythingAboutDesign Hi there, sorry - your response went unnoticed! I guess the geometry engine tries to extend the edges to meet as you said, makes the most sense. However, I have had cases where extending naturally with aligned edges to the outer surface (so an open brep) gave an unwanted result. As an example: I modelled a wing for a F-16 model, since this wing is basically a Delta-shape in plan view, to make it printable, I chose to seperate the shape into printable size parts. I cut the shape in the cross-direction (so in length-station). Then in cross-section, I created a shell that allowed for an insert to be glued in so the joint could be biscuit-ed when printed. This would allow for correct alignment of the glue joint. However, when trying to put it together, I noticed this joint lengthened the wing by about 0.3mm. This can be due to a lot of factors, mostly due to tolerances being so tight the actual glue in the joint would make it so the parts didn't meet flush. As a solution, I added a 0.4mm gap between the parts, by direct face manipulation and shifting the faces of the split body back. Since I was in direct modelling, with this edit, the connected shape was lost. After more testing and re-designing, I had to re-build the full wing solid to make the joint in another place. I tried offsetting the outer surfaces and extending them to meet. The seam it would create would be fine for the printed model itself. The non-tangency "stitched" outer surfaces would be non-tangent by a tiny amount, in zebra analysis it'd create a sort of break, perhaps due to stitching? This is cerainly unnoticable in the mesh export, but being a 3d-modeller by trade this was a huge annoyance to me. In the end, what did the trick was to fill the shell I had made for adding the glued insert, extending that to intersect with the other wing body. By combining the solids, I basically had the full surface back, minus what was basically a 0.4mm negatively embossed trough all around the wing. I selected all the inside faces of that trough and deleted them. This somehow merged the faces into what was the original face. After learning what I have in working with inventor for work and watching a ton of your videos about fusion, I've set it up correctly (and parametrically) and will never again lose geometry by working in direct modelling mode (timeline is sooo good haha). Anyways, that's a case where I found delete face to re-build old geometry. Hope that very expanded story makes sense. I'm sure it would've been possible to fix it in some other way, I probably made a few mistakes along the way trying to fix it, but it did work in the end. Thanks for your content and reply! Greetings from Amterdam, NL

[@Fusion360School]

This was an eye opener for me. There are so many nuances when it comes to surfacing. Watching this made me realise how much I still don't fully grasp about surfacing. For the four sided surface, have you tried experimenting with the extend tool? It seems to produce a very nice surface, although I have no idea what it is doing in the background. I was surprised by that fact that you could use multiple disjointed entities as a single loft profile. Never knew that one. Do you have a video that explains the differences between free edges, align to surface and align edges in the loft command? Watching this video made me question my understanding of those options😅.

[@LearnEverythingAboutDesign]

Thanks for the comment! I find it hard to believe you don't know it all with the models you make on your channel! On the four sided surface I didn't try the extend tool. Mainly because you can't guarantee that it will meet the end profile where you want, but anything is possible! On the free edge vs align edge yes i did a video here kzbin.info/www/bejne/hWiWlWyXqauKhbs It is a nuanced setting that only seems to work in very specific cases so hopefully this helps!

[@janosadelsberger]

Using the curvature flow as a guide to decide which sides to loft is great advice! I learned most of this by watching @thirtysixverts series in Rhino and Autodesk's Golden Rules for Alias surfacing so it's super interesting if and how all this carries over to Fusions tools.

[@LearnEverythingAboutDesign]

Thanks for the comment and inspiration for that video :) Alias and Rhino certainly handle this stuff way better than Fusion. They are less picky about all this. If you have Alias and need to do surface work use that :)

[@janosadelsberger]

@@LearnEverythingAboutDesign Yeah Alias is obviously build for surfacing but I'm on a Mac and as an engineering designer I'm working more on concept than production surfaces anyway so Fusion and Rhino works fine for me right now. It's super interesting to me how the tools work and in which cases they somehow fall apart. I loved Freya Holmérs video "The Continuity of Splines" just because the math is cool ;)

[@superalpha]

there is no need to patch if you have symmetry (yeah...I saw the whole thing) but great info :)

[@tonysmith7702]

Very nice.

[@keal4825]

You are so smart. Is there any advice you can give those who are learning Fusion 360 to persevere with the pile of knowledge?

[@LearnEverythingAboutDesign]

Time :) doing this over and over and never stop learning.