I have a question about curves, CVs, Knott and fillets. I cannot seem to delete certain knots… and my fillets from my AI curve vs my Rhino curve have different results.
Thanks. Please see attached video question and Rhino File.
Do you have the original Illustrator file before importing into Rhino?
I do.
Can you share it?
Your illustrator curve has some stacked control points. It’s not clear from your file or your description what exactly you want to do.
Illustrator is notorious for making very wonky curves.
as a general rule I always rebuild them.
AiCurve.ai (11.7 MB)
Sure thing. Attached is the AI Curve.
Thanks Everyone.
Illustrator uses Bézier splines and there is absolutely no control over the tangency/curvature continuity between the sections. If you turn on CurveGraph on your illustrator file you see this:
Everywhere where you see those spikes is a problem area - and the rest of it is not great either. It’s really a very poor tool for creating manufacturable objects. I suspect the spikes (stacked control points) might be due to how the different sections were terminated with the tools in Illustrator, but I’m not an expert on that.
oof…yeah that is pretty rough…
In addition to what Mitch wrote, you have some places where the curvature won’t support the 1/2 inch fillet that you were trying to make. FilletEdge will make a fillet but the surface will be garbage and may not trim properly.
In the enclosed file I rebuilt the parts with bad continuity and replace the areas where the curvature can’t support a 1/2 fillet with a true arc that is slightly larger than .5".
CurveQuestionx.3dm (2.4 MB)
This is excellent information guys. Thank you. Diving into this today.
Ok. Following up.
I am completely new to the CurveGraph tool. It’s awesome. Such a huge help. Thanks for the suggestion.
This is my new curve. (See Attached). Does this look better?
I have one question… For Jim or anyone who can answer it but Jim hit on it.
How can I tell what part of the curve will support a 1/2" Fillet? I’m probably approaching it wrong but they way I did it was I put a 1" circle inside the tightest part of the curve and it fit so I thought a .5" radius filleted edge would work. (See Attached). Just curious how you built your “true arc”?
Thanks again everyone.
Small fillets like that (I guess what you call ‘small’ depends on the thing) shouldn’t be drawn with your main curves, they should be added at the stage of filleting the 3D model.
I don’t think I phrase my question correctly.
I do my fillets at the filleting stage. I guess my question should be- When I’m drawing my initial curve for the body of this guitar is there a way to preemptively know what fillet size I can use down the road- in the tight parts of the initial curve?
I ask for a couple of reasons. 1. Jim, you pointed out that a 1/2" fillet wasn’t going to work just by looking at my original curve for the guitar body. How did you know that? You even pointed out the positions where they wouldn’t work. To me in my head it should work but sure enough when I fillet the edge I get problem areas exactly where you pointed.
Well for one thing if you extrude 'em a bit you can use the curvature analysis to find the too-small areas.
CurvatureGraph, Curvature and Radius commands can help with identifying areas of tight curvature.
Your one inch sphere may look like it fits but there is probably some amall part of the curve that has radius much less than 1.
You don’t really want anything in a spline curve where the convex curvature is even close to your fillet size if you want the result to be a good quality fillet surface. A fillet will wrap around an arc and make a nice surface even if the arc is very close to the same size. The same can’t be said for spline. Anyplace where the spline gets close to the fillet size is likely to produce a crappy fillet. Anything with a radius below 3/4’" radius will usually not produce a very nice fillet on a convex corner. A concave corner isn’t a problem.
I used fillet command on the curve to create the true arc connection. Cut a gap in the curve where the curvature is tight and you can use history and move the end points to get the fillet to go where you want it.
