Options for "offset" on curved surfaces...

[nar9607]

I'm working with some cylinders and trying to transfer some design details onto them.  Below is one example where this is the top view of the end of a cylinder.

I've done a sketch and can project that onto the cylinder, but I'd like to put a small groove around this design.  There are some similar details elsewhere in this project where I was able to offset the original sketch and extrude the resulting face to give the groove, but those were mainly horizontal lines.  Given the curves, and proximity to the edge of the cylinder, that method does not work here.

Is there any way to put a groove in the surface of the cylindar around this path?

Thank you!!!

[fulcrumusa]

I wonder if you can create a sketch with the desired groove profile perpendicular to the curves and centered on the curve point (in 2-dimentional space) and then just do a sweep along the curves?

[nar9607]

Thanks. I was originally working with a square groove, and the sweep method didn't result in a groove floor that was roughly parallel with the cylinder surface, though I'm guessing that's more my lack of knowledge than anything else. I was able to get this to work with a circular path, resulting in a curved groove, which should meet my immediate needs. Thank you!

As a side note, I'd still be interested in learning how to create the squared off groove.

[jeff_strater]

Hi @nar9607,

You are correct, sweep will most likely have problems with this geometry if you use a square profile, because of the twist.  One operation that Fusion needs to add at some point is a "surface normal sweep", where you control the twist by specifying the cylinder as a guide surface.  That's why a circle is nice - the twist doesn't show.

However, there is a way that you can get your groove, I think, using a combination of Split Face and Press/Pull.  Here is a screencast:

Good luck!

Jeff

[nar9607]

That was incredibly helpful! That definitely gets the squared groove.

One question on top of this... the resulting offset would not be consistent as you move to the edge of the cylinder (if I'm following along correctly). It's not too noticeable where you were, but as you get closer to the edge, the offset on the cylinder face would expand. Is there any way to keep that consistency?

As I type it, i'm almost wondering if I could do a circular sweep to define the offset and use those edges to define the push/pull you demonstrated in this video?

Thanks again!

[jeff_strater · Accepted solution]

Yep, you are correct.  This method does not produce a uniform offset.  You can get closer with "Project Curve to Surface", with the "closest point" option set.  But, that approach has its own problems - it is not a true "wrapping", so if it gets a long way away from the surface (which it will near the edges), you get more distortion.

However...  Your suggestion of using the circular sweep as a surface body, then using that to split the face is brilliant.  I ran into problems in my model with this approach (I got some strange sweep errors).  But I think it's a good approach to try.

Jeff

[nar9607]

Thank you so much!