In another thread that I started, I was trying to use loft and rails unsuccessfully to create a patch. I was told to make a 3D sketch of a spline and use tangent constraints to make it tangent to the two edges, thus defining the fourth edge of my patch. I've been able to do this successfully many times, but today it won't work for some reason. Anybody have any ideas why?
Tangency constraint not working on 3D spline?
Yes, it's a bug that can pretty much stop you in your tracks when working with surfaces. We (@cekuhnen and myself and likely others) have reported this several times dating back years but it still creeps up al too often.
It might even go so far that it allows you to create the constraint and then you cannot adjust the spline handle. Or you can adjust the spline handle on one side but the smoother tangent constraint on the oath rose turns red but also cannot be re-created when you delete it.
I should ad that this advice was correct and creating a blend curve is the correct technique.
Please share the model so the Fusion 360 team has data to work with.
@ryan.bales @jeff_strater can you look at this please ?
In the last 3-4 weeks this kicked me in the teeth in a personal project, in a thread where I helped a user with a 2D spline (I reported that one), and I've seen this also when helping with the model in this thread just trying to create a simple 2D blend curve.
So in essence this is not only limited to a 3D spline and the problem here is that I don't know a feasible workaround.
@Art5 wrote:
Well, that sucks.
Thanks for your reply, I really appreciate it.
Is there a workaround for this?
Are then two curves you are trying to create the spline between coplanar ?
Can you share the model ?
Where is the origin in the model ?
It is so far away from the geometry that when I try to create a new sketch I do not even get a plane to pick!
So the object in the model you shared is approximately 6 " x 3" but 60 ft away from the origin so the ratio between object size and distance from the origin is 120! That is not a good ting and likely part of this problem with creating and selecting the curve.
Extrude a small surface from the curve and use edge of the surface instead of the curve. Then you can patch it.
I would usually not use a patch but a loft, but the curvature on some of the edges of this model is garbage and prevents a loft.
Not sure what to tell you.I succeeded in doing that just before I posted, but now cannot re-create it.
Things will possibly improve if you move the geometry closer to the origin.
Accepted solution
After reading your intention to use patch where a loft is clearly the better alternative I went back trough some of your other threads.
I am not sure what experience you have in other CAD tools, but I believe part of your problems. stems from incomplete knowledge in using proper surfacing techniques, which disables you from properly identifying the source of these problems. For your work, which I assume is some form of tools & die making there is one essential tool missing in Fusion 360 and that is an untrim tool.
In this case we can get away by the width of a hair not having to use it. But there are other cases where that will not work. Something you definitely should always do before lofting is check the curvature of the edges you are hoping to loft between. If the curvature is bad you'll run into trouble sooner or later.
