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Please explain "Specified trajectory is not valid"


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I created a 3D curve from an equation. Then I used the split curve option to segment my curve into multiple trajectories. When I try to use some of these curves as sweep trajectories, I get the above message. Does anyone know what is going on? I don't understand why some of the trajectories work and some don't. I created all of them the same way.
For some reason, sweeps don't work on some 3D curves, namely Curve by Equation, and Curve Thru Pnts using the Tweak Option. There are probably others, but I don't have a list.

Try using a swept blend instead of a sweep.
This brings up another problem..... When I import the data for the sketch, I can't align it to where I would like it to. There is a free rotate and a scaling factor for the sketch I import, but I can't get it to align to the exact points I want. Is there a way to highlight the whole sketch and permanently group them so I can move them together?
PTC's TPI 21286 gives a good list of what type curves work with curve sweep and curve blend features.
u can make a point in the active sketch and allign the imported sketchs point with the active point of active sketch. i faced the same problem when i was modelling a tooth u can also create perpendicular centerlines in both places so u can allign them atleast with 99 % accuracy.

The reason sweeps dont work with some 3d curves is because you need a reference for the section. You can get around this by using a var sec sweep. There is another way around it but I havent seen your sketch so its hard to explain.

This is a sore point for me because rhino can sweep almost anything along a curve.

I have mentioned this at the TC meetings and the programmers say that rhino is crap and they could code it in a weekend. If thats the case they should take twenty minutes and write this code for us.

Sorry for the rant, Iam warming up for the TC meeting in Orlando next week :)


Its a really cheap surface modeller that I use as a file converter. I can open/ create just about any file type.

I use it to quickly pare down my clients iges files before importing to pro.