Difficulty creating a simple loft

[EngineerJim]

I want to create a loft from a rectangular surface with rounded corners to an "obround shape" directly above it. The only way I can even get it to create a loft is with the following options:

Note that it doesn't matter if "simplify surface" is checked or not.
Here's the twisted result I'm getting:

The really strange thing is that I'm simply re-creating a new sketch using the same steps I did on an older one where the loft worked.

I've tried drawing the "obround shape" manually with a rectangular box and two half circles with the same results. I then added a 3D drawing connecting the midpoints of the arcs and straight edges to the midpoints of the rectangle lines below them. I tried to select the 3D drawing as "guide curves" but the loft doesn't work at all then regardless of if I choose global, local or tangent.

Please help.

 

[bigseb]

Works fine. Top tip: guide curves need to be single sketches.

 

[EngineerJim]

Ah so the individual sketches are what I was missing. Thanks a ton. There's not a whole lot of help in this area in the Alibre help files.

 

[EngineerJim]

So, I created the 3D drawings separately and I still can't duplicate your result. Here's the reason it's giving why.

 

[bigseb]

Delete your loft feature recreate but do two things differently:

1. Sketch 3 is made up of construction entities convert them to sketch geometry
2. when selecting the guide curves you need to select them in order as they go around the loft sketches. You can't coss over in your selection.

AD's loft tool is super fickle to work with. Sadly.

 

[EngineerJim]

Thanks again for the reply. I'm not sure what you mean with construction entities vs sketch geometry. Is it because I used "project to sketch" and have the lines "maintain association to source entity"?

Never mind; I realized that the lines in the sketch were projected as reference lines rather than "regular" lines. Thanks!

 

[OTE_TheMissile]

Thanks again for the reply. I'm not sure what you mean with construction entities vs sketch geometry. Is it because I used "project to sketch" and have the lines "maintain association to source entity"?

Yeah, I've run into that before too. Instead of using Project to Sketch, redraw the outline of the surface and constrain it with a bunch of Coradial and Collinear constraints. It shouldn't make a difference but it does; like Seb said, Lofts are fickle.

I generally only use the Project to Sketch feature when I'm drawing something up quick and dirty. Long term, I find it's better to draw my own lines.

 

[DavidJ]

In Sketch 3 you have used reference figures, not regular figures (as BigSeb pointed out).

I had to set your guide curve conditions to 'local'.

The problem has nothing to do with project to sketch - except that you must have chosen 'reference figures' rather then 'sketch figures' as the output type.