Yes that is the one I normally use, I found it best some time ago on airfoil sections where curvature is important. One has to adhere to the dimensions there if at all possible given its role. Some items such as cowlings are not mm critical for performance.
These input curves are never going to give a nice surface. If you
rebuild to the same number of points and degree as the original curves,
you’ll probably get a negligible deviation, iron out the kinks and end
up with an acceptable surface. Also, decide what tolerance is acceptable
and rebuild the input curves further…
Fully agree and have remedied such before seeing this post.
after following Jims first (kind) advice I applied as advised the Curvature Graphs and also have redrawn with evenly spaced and far far less clicks the curves using InterpCrv Knots=Chord. I also redid the base rail curve.
What looks good to the eye and follows original dimensions now needs graphs and point usage analysis to be acceptable, now I understand that. Trusting in what the curve tools deliver isnt enough. W dont get told this in the help on curve tools, its what data they follow that causes the problems.
I dont see anything wrong in trying for a single rail sweep. The command exists. I wanted to see how close to what I wanted, the two frame profiles and base curve were when swept. I dealt with the kink in the base curve and the sweep was transformed ! That base curve was a dupe edge of two separate cowlings which when they were skinned separate never led me to notice that together there was a subtle kink.
I then added in a second upper rail which has two designed S bends in it, the result gave me what I wanted and showed that still without a third middle level rail the resulting skin was bulging out and not as per the real thing. There is no other data for the area and I am having to try and make frames from intersections with skins of my station lines. it can become chicken and egg situation. I need the skin to create the section and I need the section to create the skin !
If someone looks at it and thinks he needs another rail, yes I am fully aware of that, its just that the data for it simply doesnt exist. I have to use all my skills to deduce with a 2 rail sweep where maybe the second rail and shape could be. I do know exactly what I am doing by the way, and work completed is testament to that and also the help received which is not project specific but just use of rhino commands, bug checks, I have spotted a few, and so on.
V4 obviously led me to be able to create sweeps using curves that are unacceptable to V5, thats not my fault, as Jim says, V4 gave me a false sense of security.
what V4 is doing is there is kind of disturbing in it’s own way too
Now that I know about CurvatureGraphs, I can find and fix such for V5 acceptance. I am learning and there is a lot to learn in a short time, coupled with the massive workload to fit in as well for a deadline. There are no tutorials specific to aircraft building as I am having to do. and 1;1 training is massively beyond my pocket and I would expend time training the tutor on this as much as he me ! Its a hell of a jigsaw and beyond the understanding of some. If it were travel, then to go from London to Paris one has to go the opposite direction, then north via the arctic, then head back on oneself then via America and then back to Paris via Spain.
I am also throwing aside the expectation on me that lines must adhere to original dims, keeping that set for that persons requirements/approach, and creating a rhino friendly set for skinning and sanity and forum acceptance. Deviation might be 1mm at most, often less and I am happy to throw in 0.3 or 0.5mm adjustment, enough to make a massive difference and I now do that. What happens then is it doesnt abutt to another part, as both were designed on paper, so I make that part fit the skinning friendly edge as well. A tail chase hopefully doesnt result. . At least my lines and skins now are forum approved, even if they deviate by more than the indicated manufacturing tolerance.
I have just followed another dimensioned drawing of what should be a gentle sweeping degree2 curve and curvature graph shows two let alone one S curves though the human eye cant see them and neither could those armed with splines and pencils many yrs ago ! Not my fault, I now will kill those with the graph etc.
Some work requires high tolerance and other lesser tolerance and a low tolerance job (1mm ok) requiring a 0.1mm kink sorting makes the client think I am over fussy ! However Rhino requires it. All has passed recipients standards for machining.
Very grateful for help received in use of Rhino so far and for exploring the hidden depths of this program. I hope others also benefit from what I hope are intelligent useful posts and not dumb ones.