I’m going to model this rim with all the details. Can anyone give me some guidance about how to set out the modeling and rich the final model (a model without any sharp edge)
Hey, I‘m just on my phone and I hope to still give you some valuable hints.
The „ring“ is simple. You‘ll need to draw a section and create a circular profile. Since in automotive these shapes would need to be represent with beziers, usually you divide the ring into 4 segments with 7 cps in u direction.
In Rhino I would stick to a full circle using multispan. Much easier to create here. The profile already includes fillets. Be aware of the fact that any shape in automotive is crowned. Ideally with propotional strength. So no lines within your profile!
The front surface here look like to consists of 3 surfaces, two bigger surfaces and one blend in between. The difficulty here is the center. So the best strategy is to close the ring by creating it from a profile again. Keep a tiny hole at the center, this prevents surface singularity and little artifacts.
After having a closed ring you start with the arms. Simply do one arm and exploit symmetry for the rest. Simply draw curves in 2d and project them onto the front surfaces. Trimming them and afterwards you flange/taper the surfaces pointing to wheel axis direction (y axis in automotive) . Usually they are created with around 10 degrees in y direction. Afterwards the last cp row is pulled back in order to guarantee an draft angle of 3-5 degrees by having crowned flanged surfaces. When all of them having the same degree and crown factor, the output will look already very good. Always be aware of cp reduction. This simplyfies drafting and matching. When flanging/taper always check if all flanges are matched correctly within.
Build details and other remaing surfaces. Before blending or filleting always ensure to have positional matched main surfaces. A watertight theory. Exceptiona are possible, rarely and not in this particular example.
Once you have done that, you‘ll need to create the fillet blends. This will get difficult with Rhino but its not impossible. Use chordal fillets. If the true radius is above 1.5 mm then do G2 fillets, else you can stick to G1 fillets. Make sure all fillets look equal in size not in true radius. This is important and guarantees a great look. corner blends can have G1.
Apply symmetry, trim the rest. Done.
Rims are very good objects to learn surface modelling in automotive. Have fun. Sorry for not posting any pictures, but as I said: I‘m just using a phone.
Thank you for guidance. I tried to do some parts of your guidance. please look at the file and check it out.
Now, I want to model the spikes. They need some more attention. As you said, I created three same surfaces.
Please tell me about these three surfaces. What are they?
I think the first and the last one belongs to the main spikes and the middle one belongs to the small spikes which has been attached to the main spikes. Is it right?
I’m working on Rhino 6. I saved it as Rhino 5 file:
T01.3dm (885.9 KB)
T02.3dm (1.7 MB)
you already got the ring and the front surfaces. Well done. Looks good .
So ignore the 3 srf thing. Just continue with the flanges. Now all you did was extruding in wheel axis direction. But this is way too simple. Can‘t remember the correct command for Rhino, I think it is _taper extrude. Set to 10 degrees. After you increase degree from 1 to 2 to get 3 control point rows in extrusion direction without changing the shape itself. The last row has to get moved in normal direction to crown the tape/flange surface but also to ensure a certain draft angle.
But unfortunately tapering results in non-solid shape.
Are you referring to extruding the face surface? Are you using ExtrudeSrfTapered with Solid=Yes? If so it appears that ExtrudeSrfTapered may have a problem with Solid=Yes for 360 degree surfaces of revolution.