>The next time you run into this please save it off and send it on over to me so I can try to see what's going on there.

See my original post for a file. You can see the error on the scaling rail when zoom in at the big end. All osnaps were on when drawing the scaling rail curve.

For the scaling rail I clicked on the top of the big end curve with a "on" osnap in perspective view, I then went to the side view and plotted the other two points and then I went back to the perspective view with another "on" osnap on the small end curve. Originally it missed both times on each end curve but mostly it misses on one of the end curves.

Perhaps I need to zoom in more when drawing my curves and the "on" osnap would work better ?

Sorry I can't post a video to explain how I did it but hopefully my text make sense.

Hi Kevin,

> See my original post for a file. You can see the error on the scaling rail when zoom in
> at the big end. All osnaps were on when drawing the scaling rail curve.

When I examined your file, I do see an error in the sweep surface on the big end, but I can't really see any osnap error in the scaling rail not touching the end profile there, it seems to end right on it... But like I wrote above it's not necessarily the _profile_ that the scaling rail has to cover, it's a set of planes that come up from the rail curves that the scaling rail has to cover.


> Perhaps I need to zoom in more when drawing my curves and the "on" osnap would work better ?

It can be a bit easier to control things in general when zooming in, but it shouldn't make any difference for whether "on" snap is on a curve or not - when you get on snap the point should definitely be on a curve...

Could you please give some more info on the snap error, right now I'm not understanding it.

- Michael

Hi Kevin, so something else that I don't quite follow:

> For the scaling rail I clicked on the top of the big end curve with a "on" osnap in perspective view, I then
> went to the side view and plotted the other two points

So with this sequence, it should result in those first 3 points of the curve all being on the same plane that's parallel to the side view.... But yours are not..

- Michael

Hi Michael

My mistake, the error is on the small end.

I think when I drew this I must have used the side view to snap to that last point. Because the small end curve isn't exactly perpendicular to the view it finds the nearest "on" which ends up slightly off.

When using perspective view to draw the first and last points of the scaling rail, all is working well. I cannot recreate any errors.

Sorry for the red herring.

Hi Kevin, no problem, let me know if you run into another kind of problem case in the future.

You wrote:
> I think when I drew this I must have used the side view to snap to that last point.

Yeah that can cause this kind of result because "on" snap (same as any object snaps) in the 2D views like the side view will get projected to the current drawing plane. That's so that when you're drawing things in a 2D view that you'll also get a planar result.

You can change that behavior with a setting under Options > Snaps > Object snap options > "Project to plane in ortho views" checkbox. When you unset that then object snaps will go directly to the 3D point snap location with no projection. But that also means that things that you draw in 2D viewports can be easily non planar curves squiggling around in 3D.

By default that projection is enabled so that in 2D viewports there's an emphasis on generating 2D results but picking points in the 3D viewport lets you do freely squiggling stuff.

- Michael

Thanks for the response, I much prefer projection being enabled without having to setup a workplane or cplane. Its a much more intuitive way to draw things in 3d.

Just got to remember that there is a disadvantage to this functionality when you work in the ortho views.

Yeah I've run into that problem w/the sweep and didn't understand why the bunches at the end were happening as well!


It would be great, Michael if you could internally make the curve extension - it's helps avoid breaking the "modeling zen" where "stuff just works" as expected.


-Will