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Can we have a sketch conic?
mark_biasotti
Member Posts: 123 ✭✭✭
I have a project that current requires a sketch conic as the basis of the main feature. Is it poisible to have a sketch conic in Onshape?
P.S. Now that SW has them I use them all the time. I refer to them as a poor-man's spline but that is not a fair discription because they are so much more than that. I mention this because for introduction into a new MCAD machine design product they really should come BEFORE splines.
I fought like hell for 10 years to get them into SW - hopefully I don't have to do that again with OS :-)
Mark
P.S. Now that SW has them I use them all the time. I refer to them as a poor-man's spline but that is not a fair discription because they are so much more than that. I mention this because for introduction into a new MCAD machine design product they really should come BEFORE splines.
I fought like hell for 10 years to get them into SW - hopefully I don't have to do that again with OS :-)
Mark
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Comments
Dries
Or, are there situations where having separate curve features outside of a sketch would be more beneficial?
Yes, but of course, if they can be both 2D and 3D sketches and if they provide everything a 2D or 3D curve feature can do. ProE and NX (as did many others) took the route of having distinct curve features (as did SW in the early days) but in the end, they are not as versatile as a sketch curve, because of the constraints and dimensioning that you can apply to them. In 2D it is useful to have the spline as a sketch element because you and seamlessly combine them with other sketch geometries; if it were it's own curve feature, you could not do that (so easily.) As a point of reference, SW 3D sketch spline and Style spline are MUCH more versatile than the ProE curves because of the D-cubed contains (2D) and the dimensioning that you can apply to them, not to mention the built-in sketch environment familiarity that is inherent to them vs. having to learn a 3D curve feature. The downside is the non D-cubed 3D constraint solver in SW which make them very unreliable and buggy - Ask Dave C. about that... :-)
In SolidWorks, the new Style Spline is FAR better than the legacy spline in terms of controling curvature and quality (of curves and surfaces). In any surface modeler (Rhino, Alias...), if you're serious about the quality of surfaces, you NEVER build surfaces from B-splines. ALWAYS use CV-controlled single-span curves. I think an important part of Onshape should be about teaching best practices. Single-span curves as input for surface creation is an excellent example of that...
Simply provide only best-in-class tools. Position Bezier curves as the default 'style curve'. I will allow you to add B-spline too, but only for cosmetic wires and stuff.
I've witnessed too many horrible abuses of B-splines...
Dries
What we wanted to achieve for pre-production was a simple spline that could be used by machine designers for cable runs, hence we implemented the current splines that can have fixed length.
What we want to achieve for styling purposes needs to be different and right first time. So I'm hearing CV curves, including conics, are essential. So are well-behaved 3D curves that you can easily and efficiently manipulate and constrain to adjacent geometries. I also get that to create profiles you need awesome curves in the sketch.
If we provided powerful curve features outside of a sketch, would that be acceptable too?
Andy
"If we provided powerful curve features outside of a sketch, would that be acceptable too?"
My own experience with 'curve features' is limited to SolidWorks. Are you talking about projected curves, helix, split lines etc.?
Obviously those type of curves are needed. Oh, and iso curves...
Dries
If you want to see some great examples of associating outside sketch curves check out Shark FX or Ashlar-vellum Cobalt. The core interface to these apps has not really changed since the early 90s - we are taking full 3D curve creation and editing in 3D space. Rhino does much the same now but the interface is not as good and the downstream associativity is limited to one feature. Shark and Cobalt have full associativity.
Another one to check is SolidThinking. again the interface is a rather clunky but it has more surfacing tools and constraints than either Shark or Cobalt, again with full associativity. Frankly SolidThinking is a better product than Rhino but it is very underused outside Italy and France.
Great points.
I agree that Onshape should focus on 'clean' curve creation tools. That's why I much prefer Beziers (SW Style Spline) over B-Splines (legacy Spline). In my book too, curve-on-curve projections are a big no, UNLESS Onshape provides (awesome) Class-A curve and surface tools for reparametrization. A GREAT example of this is the Autodesk Shape Modeling Plug-in for Rhino (which I use and find seriously awesome). It has a very powerful and quite intuitive set of tools for high-end surfaces. Some of the things it can do: reparametrize projected curve to a single-span curve of given degree (with tolerance evaluation), fit an untrimmed surface onto a trimmed surface, 4-sided surface matching, CV pulling of surfaces while maintaining continuity at boundary etc. Some people say it is more powerful than ICEM Surf...
Great suggestion about the pipe tool. This is exactly what (I think) Onshape needs: design-centric tools, not just CAD operators. Like Kevin suggests, it could be automated 'macros' of laborious/cumbersome/repetitive tasks.
Dries
SolidWorks, the new Style Spline is FAR better than the legacy spline in terms of controling curvature and quality
Thanks - one of my last projects I initiated and worked on with my colleague Rob Jost.... We fought hard to get that over many years. Nice to hear you like it.
Mark
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