Help with Loft

[rkagerer]

I'm designing a circular bracket with a curvy cross section, that meets up with a flange, incorporating some ribs along the top and bottom edge. I've been struggling the last few days to create clean geometry where it all connects.

Here's the closest I've got so far (SLDPRT file linked):

https://www.dropbox.com/scl/fi/p961rvrd ... d1ve4&dl=1



I'm not happy with the fillet transition at the right side of the picture. It's "sharper" than I'd like, and doesn't merge into a single fillet line the way I accomplished on the left hand side.

At the moment I'm using a loft with several guides to mate the two pieces. I used a couple 3D sketches to lay out the upper and lower edge of the rib, and while I'm competent at sketching in 2D I always find it difficult to make curves in 3D space go the direction I want - especially once you start adding tangency constraints. I think I might need tangency with the flange at the right side, but my attempts to achieve that haven't been filletable. I'm also frankly unsure what to do with the right edge of the sketch profile that defines that side of the loft - highlighted thinly in orange above.

Note the circular flat area is where a bolt hole will be placed, and its head will rest against that surface. The rib can't block being able to insert the bolt (there's a sketch that defines head clearance). There's also a little too much "underhang" on that side just beneath the rib, which is unnecessary and could pose a machining problem (for now I'm prototyping with 3D prints but the final part will be stainless steel).

I'd also really like to figure out how to make this geometry a little less fragile so that I can make tweaks in a few key parameters (e.g. collar height, flange width, etc) without having to do a lot of reworking downstream.

Here are some photos from earlier attempts. I initially tried to model the rib with a simple extrude from the top surface of the collar, but it didn't come out very clean once filleted: https://imgur.com/a/ruX0Aol

Grateful for any help from someone with more SolidWorks experience than me!

ps. Cross posted this over at the official SolidWorks forums but I hate that place ever since the "3dexperience" overhaul.

[matt]

It's best if you can start out with as few edge breaks as possible. That would mean you make the main outer shape as a single feature, preferably with a spline so there are no topological breaks caused by line-arc-line sort of features (or even arc-arc-arc). To really make this clean, you'd need to start over, but it should be faster the second time. https://episodes.dezignstuff.com/blog/a ... -geometry/

If you want to just proceed with what you have, use the Delete Face to get rid of the fillet faces you don't like (and ideally a little more on each end). Use the Boundary surface instead of the loft. https://episodes.dezignstuff.com/blog/t ... y-or-loft/

Also, I'd turn on the option to show tangent edges as phantom. This will help you get a quick visual on if you have any serious tangency problems. Then I'd also run a deviation analysis to get a more detailed look at the condition of the model. https://episodes.dezignstuff.com/blog/tools-evaluation/

[rkagerer]

Thanks for your response and sending those links. I had a thorough read of the first one and will delve into some of your other articles to learn more about surfacing. I've tended to avoid splines when I can as I find it harder to exert control over them as precisely as e.g. arc segments (and ran into some other limitations I can't recall now) but I recognize it's what's needed for this shape.

Would you model the fillet manually as part of the shape, or add that afterward with the fillet feature? I'm not sure where my boundary curve(s) should end to produce a smooth "Y" transition at the red circled connection.

I could probably benefit from a little more hand-holding here. If anyone wants to take a crack at showing me (even partially) how this should be approached I think I could learn a lot. Rolling my model back to before the features are created leaves some fairly simple and self-explanatory sketches and planes for the edges I care about, and might make a good starting point. Alternatively, I've "started over" a couple times on this and am not opposed to that.



I'd also be open to paying for some instruction on this (like on a Zoom session or something) and making it worth your while if you'd be interested in that.

[Dwight]

I've tended to avoid splines when I can as I find it harder to exert control over them . . .

I recommend Style Splines. I find them easier to control. The methods of control seem more useful and stable.

Dwight

[matt]

I'd also be open to paying for some instruction on this (like on a Zoom session or something) and making it worth your while if you'd be interested in that.

If you're serious about that, just go to the Surfacing Episodes site (https://episodes.dezignstuff.com/blog/) and go through all the topics listed in the Table of Contents on the right, and then you can use the Donate button on this site to donate what you think it was worth to you.

Matt

[rkagerer]

Hi Matt, was serious, just tight on time and had in mind a little more personalized of a crash course using this specific project as the 'training canvas'. I'll PM you. In the meantime, immense thanks for contributing such a great corpus of materials to the world via your site.