Subdiv is maybe not for your case ;)
But can be useful for imagine creative forms!
there are for the moment only 5 principal functions ;)
Native Extrude + special SBridge, SsPlit,Sscale, Subdive
as you see fillet is special ;) And you can't made fillet on the "edges" of a volume subdivided!
Yes, exactly what I mean!
Usually, in Rhino, I draw a circle with the given diameter and then create a form; moving some points I try to achieve the model I need and use the circle as reference. So I try to be nearest to the circle, it doesn't matter of the precision, because when the ring is casted and polished it change its dimensions.
The important things are the setting for the stone that must be precise... but I can use nurbs with standard commands.
So, yes... it's good as you wrote!
I think that, starting from a cube, I can add faces following the guide circle to form a ring... right?
Hi Pilou, first af all big thanks for your fantastic input, much appreciated !
One question: what do you mean by "special SBridge", is this different from
this version:http://moi.maxsm.net/files/scripts/sBridge.v.0.71.2015.03.26.zip
???
Thanks again + best wishes !
Hi Marco,
not sure if this is the result your looking for but this was produced by using half of the helix (outer diameter of ring).
I extruding it to max depth then trimmed as Michael as shown.
I then shelled it and filleted.
It was necessary to trim the solid where it was going to join in the middle as this was not flat due to the shelling.
I then copied the half revolved it 180 and joined.
Hope this helps.
Barry
I follow Michael advises and yours, but... how did you solve the issue in the point where it has to be join?
Mhhh...
In all this job, a profile is missing I think!
Hi Marco,
did you use the shell command (see photo's).
There is no need for a profile.
Make sure to do the filleting on just the half as I had problem trying to fillet after joining.
Cheers
Barry
exactly Barry... that face is not squared and it's rotated, so when I copy-rotate the solid, the result is what I've attahced to my post before...
I can't figure out how to solve...
I followed the same yours steps!
Hi Marco,
it looks like you have extruded the half helix square to the angle of the helix and it should be square to the axis.
If this isn't the case please send me your file.
Cheers
Barry
Ok understood...
Thanks.
What about the fillets, now?
I've cutted and reconstructed the surfaces to avoid crossing points and then launched the fillet... but you can see the results... any idea on how to apply correctly it to the model?
Normallly you must have the same fillet along all the volume (don't accept the fillet if you want the following possibility)
then free to you after to make any new "variable fillets" during the same session of fillet on some edges!
Pilou... or maybe Frenchy? ;-)
The bottom small fillet is ok... The top one, instead, is just a suface that moi has used as filletting surface, so its another surface! Just delete it and you have the original solid. I left it just to make you know where is the issue.
Here attached you can find the solid without fillet
Hi Marco,
not sure what your problem with filleting is ?
Do all large fillets first then the small ones.
Attached your test with fillets.
Cheers
Barry
Ps: just found a problem with your large fillet where you have tapered it from front to back you have 3 edges created by the fillets converging at the front so when trying to add a fillet on the front edge no go.
I selected the 3 edges of the top ran 0.7 fillet and second fillet points for a 0.4 fillet at the back and that is what I have posted.
Are you trying to get the side fillets to match the front fillet where they meet at the front ?
Hi Marco, so some of the fillet problems are due to low surface quality in the end pieces:
For example here it's pretty subtle but I noticed a wobbly shape here:
The surface control points kind of fold back on themselves here:
This surface does not look like one that would result from a fillet, are you probably making these by using the Network command? If so then that's the problem, you would want to instead use the fillet command to make these big rounded areas too, with a larger fillet radius.
Also this one along the side is problematic:
It's not good for a NURBS surface to have 2 of its natural edges meet up smoothly like that, it makes the surface compressed and messy there. It is easy for the surface normal to wobble around in a small area with stuff like that. Instead things like that should be formed from a larger surface that has distinct corners and then it's trimmed rather than the surface directly constructed to an irregular boundary like that.
Putting in Network patches like that will also result in your surfaces not meeting up smoothly to each other which is then a lot more difficult to fillet. Like here for example I don't think your model is smooth:
It's a lot more difficult for a fillet to be constructed across a sharp edge like that especially if it is somewhat close to being smooth. Fillet surfaces only naturally meet up with with each other end-to-end when the surfaces that are being filleted are smooth to each other. When they have a sharp corner the fillets do not naturally meet up instead they have to be extended and intersected with each other and when things meet at a shallow angle that is nearly smooth it means the extensions have more like a zone of intersection rather than a crisp intersection.
Some other areas that kind of show a "patch by patch" fill in construction method are stuff like this:
What I would expect for that surface is for it to be a longer piece that is trimmed instead of the surface being directly contained inside these end edges.
I'd guess that maybe the rounded end was sort of "tacked on" ? Instead what you want is to have the entire base model extend further and then use filleting to make those large rounds instead of trying to manually grow them on to the end.
Hi Marco, so you'd want to do it more like this - starting with the main object which is already extended as far as you need (so no "tacking on" needed), do the fillets in order of largest to smallest, so starting with this one:
Then next these:
Then select the whole model and do the smallest radius:
Don't try to simulate a fillet by filling in areas with Network, just in general you want to be working more by carving away pieces rather than filling in pieces patch by patch.
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