Setting Orientation along a 3d spline

[jroddds]

I'm trying to sweep a profile using a 3d spline as a path.  The issue I run into is that the profile twists along the path. 

Here's what I'm trying to do:

I have a tapered cylinder that I am trying to add a thread to. (Does not fit a standard thread model in the library)

So I created a 3d helix-like spline to sweep a triangular/trapezoidal profile.  Unfortunately it twists and then cuts into the face of the cylinder.

Seems the the profile just wants to stay tangent to the 3d spline which twists as it helices.

Any advice would be greatly appreciated.

[michallach81]

Hi, your profile sketch need to be perpendicular to path. To do that go to CONSTRUCT tab select "Plane Along Path" tool, then choose your helix, then you need to specify value from 0 to 1, it would place plane at beginning (0) or end (1) of helix, you can also drag the arrow to do it. On this plane you can draw your profile. To draw profile correct, start sketch on this plane and at pick Inersect tool and pick helix, that will give you point in which your plane inersects helix.

[jroddds]

I haven't had any trouble creating a profile to sweep.  My trouble is keeping that profile from twisting along the path of the helix.  The trapazoidal thread looks fine at the location of the sketch, but 1 rotation around the helix and the trapazoid is upside down or sideways.  It won't stay oriented toward the face of the tapered cylinder.

Maybe I'm asking too much of the software?

[michallach81 · Accepted solution]

You've been right, sweep is not any solution, overall way of making sweep (profile perpendicular to path) is good, but not in this case. I've played a little bit with helix like sketches.

The way I've make it possible is to loft profiles (one per half of revolve, which is middle plane crossing helix) in order (ascending or descending) and picking helix as a centerline (even if it's not a center of profile sketch). I've made a screencast: 

http://autode.sk/1Q9129B

Now you should be able to make desired geometry.

[innovatenate]

Currently, there are no twist controls for a sweep feature. @michallach81 provides a great workaround with the loft command, though! 

Adding twist control to a sweep may be a feature worth requesting in the Fusion 360 Ideastation. Let me know if you post an idea! I'll vote it up!

Thanks,

[jroddds]

Thank you.  This works really well.