Can't get Intersection Curve to work

[Witsend3486]

Hello,

The subject says it all.  I have this example of my efforts:

http://a360.co/1P4wCUP

I've tried everything I can think of (including using Patch to extrude the outer plan (XY) curve into a face and projecting the lateral curve to it), but everything results in a

Project to surface failed, please check the surface or the vector!

message, which means nothing to me.

This seems to be a relatively rare topic in the forum.  I did find the exchange and screencast from back in February, but this did not provide enlightenment.

http://forums.autodesk.com/t5/design-validate-document/how-to-do-3d-intersection-curve-like-in-inven...

Invoking the Intersection Curve command before starting the sketch didn't seem to make a difference and, even if it did, it would result in an awful lot of sketches because I want to intersect the entire lateral elevation curve against both of the plan curves (and in my real application, considerably more).

Also, I don't see how my example differs significantly from the screencast except in complexity, and then not really by that much.  Is there something in the screencast I am missing?

Additionally, is there some way to get the command to accept multiple curve segments for the first input to the command?  I tried holding down the Ctrl key per something I read in that February exchange, but that didn't work.  Ultimately I want to intersect the whole lateral curve with both plan curves so that I end up with two rail curves for a Loft operation.  It is not clear to me that a bunch of curve segments that happen to end and begin at the same point will be accepted by the Loft command as a single, continuous rail.

This is not a rush item, so there is no need to drop everything to answer right away.  Also, if I'm not doing the public link right, somebody please let me know how this is done.

Regards,

Bill

[jeff_strater]

Thanks, @Witsend3486 for the post.  I agree - I tried to use Intersection Curve today, and frankly, I can't figure it out, either.  I get the same results you do.  It seems that this command needs some attention.

I was able to get what I think the results you want, using Project Curve To Surface.  It works, but I admit that it is not as straightforward as we'd like.  Hopefully we can fix that soon.

Here's what I did:

Hope this helps,

Jeff Strater (Fusion development)

[Witsend3486]

Jeff,

I did as you suggested and I do get the desired curve.  Whether or not it works as a rail for a Loft command remains to be seen because I haven't gotten that far yet.

While I am getting the result I want, I think I will not check it off as an "Acceptable Solution" so that the Intersection Curve command remains and issue for the development team.

I must say that, as I have worked with it over time, I have become very impressed with Fusion 360 as a tool,

Regards,

Bill

[Witsend3486]

Jeff and Others,

Apparently what I'm trying to do can't be done, at least in the way I'm trying.

I'm trying to do a 3D Loft al la:

When I try the Loft command, the 3D curves generated by the Project To Surface operations just aren't selectable.  However, I do get what I want when I do it as a Sweep.

I do get a bit of a glitch on the outside edge:

 

I suspect that is probably my fault as I do seem to get double line segments when I intend to click for only one.

At any rate, I'm progressing toward what I want.  I forgot to say it last time -- thank you for the very quick help, Jeff.

Revised project reference:

http://a360.co/1Mrw8S1

Regards,

Bill

[jeff_strater]

Hi @Witsend3486, no worries, I wouldn't mark this resolved, either.  I agree that intersection curve does not work well, and is confusing at best.

Regarding your latest loft, I think I know what is going on.  "regular" rails (as opposed to "centerline" rails, which is what your example uses), are very picky.  For a rail to be valid, it has to precisely intersect the profile (in my experience, it is better to have rails intersect at profile points), and they must be tangent continuous.  In your example, I can use one of your rails as a "regular" rail:

But, the other rail, I think, has some problems:

In the circled area is where I suspect the problem is.  I would have this rail precisely map to the closest profile sketch point.

Don't know if this helps or not...

Jeff

[Witsend3486]

Jeff et al,

I managed to get the Intersection Curve command to work. Apparently a key step is going into

Preferences > General > Design

and checking "Allow 3D sketching of lines and splines".  You can only do one segment of the first input curve at a time, so if you have a long, complex first curve it is going to take a while.  (I think I tried holding down the control key while selecting the first input curve, but that didn't seem to do the trick.)  Also, prepare to ignor a lot of error messages -- I don't think a single segment of my example (below) did not produce an error message.  But even with all that, a sweep along the generated curves worked.

I'm still not going to mark this as "Solved" because the command needs a lot of work by the development team.  The ability to accept the entirety of a compound curve for the first input would be a real step forward.  Also, graying out the command in the menu when the preferences check box isn't checked might be useful, too.

My example:

http://a360.co/1SClrB7

It's supposed to be the core of a dual train pipe swap valve -- one way connects A to A and B to B,but when rotated 90* it connects A to B and B to A.

Image:

Regards,

Bill

[moth3r]

I cannot get intersection curve to work either! How do I generate a curve from two objects intersecting each other? Intersection curve is actually generated but button to confirm that action is grayed out?

[laughingcreek]

It looks to me like your trying to use the wrong command. Intersecting curves is a projection of 2 different 2d curves into 3d space. (you don't even have a curve selected for the first curve in your screen shot) Hard to tell what you want, but If your trying to get existing edges to project as 3d curves in a sketch, then you need to use "include 3d geometry" Other that that my suggestions are thus- -start a new thread. tacking a question onto the end of a years old thread is a terrible why of getting help. more eyes will see a new post. -attach your .F3D file to your new post. hard to trouble shoot or understand from a pic.

[moth3r]

Well, I wanted to extract the curve from the place where two bodies intersect. I was mislead to this part of the forum by the look of the actual icon (3D intersecting curve) and short description "Creates 3D sketch curve from intersecting geometry". I would include the image of both but my toolbar is now gone from the forum post editor (yet another bug :D) Is there any other way to extract the curve from the surfaces of two bodies where they intersect. I don't think I can include object edge when it's not yet generated. I appreciate the help and your swift reply in any case!

[laughingcreek]

There is not a function for directly creating 3d sketch lines from the intersection of 2 bodies. You will have to exicute a command that forms edges at the intersection first (such as combine). The approach you take will probably depend on your geometry.