Need some help with connecting spline rails to other sketches for lofting please!

[vanessa8PBYS]

I am BRAND new to Inventor. Taking a class that is just teach yourself with a textbook and activities. The first task is so basic - I have to do a rectangle to round loft, with a spline on each side as rails connecting the rectangle and circle. I get an error each time and I am assuming it is because my splines don't connect/close/intersect with my circle and rectangle. 

I have looked over my textbook a dozen times, searched forums, YouTube videos and anything else I could find for help on the internet. Everywhere says "make sure your rails intersect the two sketches or you will get an error message - this is the biggest problem I find with students" etc.

I cant find anywhere how to actually make sure my spline is connected. It is just telling me everywhere that is has to be connected without telling me how!

I use AutoCAD daily, where snapping to a specific point is so simple and visible. I can't for the life of me figure this out on inventor. I have all my snaps on and I can't seem to find any constraint that will work for this situation (or for me I guess). I've tried tangent, coincident, perpendicular and concentric and I can't connect the spline to the circle. It is on a different plane but shouldn't it still snap to the circle to close the spline?

Any tips at all are welcomed! Sorry for rambling it just can't be this hard and I didn't think I was this stupid!

The task instruction is typed out as follows (for sketching the rails): Create 2D sketch on YZ plane. Draw spline on one side/project geometry - Y axis/mirror Spline with Y axis mirror line.

[b.mccarthy]

On lofts like this, I sometimes find it necessary to add points to the circle and rectangle sketches where the spline will intersect. These can then be projected onto the spline sketch to be used as start/end point of the spline.

If you can post this, it would be easier to track down the problem.

HTH

[vanessa8PBYS]

Thank you for replying, I gave it a go with the points and still no luck...It must just be me not knowing what i'm doing!

[kacper.suchomski · Accepted solution]

Hi

Some comments:

1. When a @b.mccarthy  wrote about points, he meant projecting the geometry of the sections (rectangle and circle) into the guides sketch in order to precisely position these guides.
   Points are redundant in section sketches (unless the geometry requires you to add them for ease of projection and constraint later on).
2. The guides were loose; they weren't bound to the section sketches, they were flying freely in space, so Inventor couldn't use them.
3. When you project sections, you can constrain the guides to the dimensions of the sections using coincident constraints.
4. Your sketches are not parameterized. They have no dimensions.

[johnsonshiue · Accepted solution]

Hi! The step you missed is projecting the points to the Rail sketch. Please take a look at the attached part.

It looks like you will be creating Loft features quite a bit. I suggest you look into Fusion 360, which may be more intuitive to create Loft geometry as a beginner.

Many thanks!

[vanessa8PBYS]

Thank you for taking the time to explain and make a video. Like I said I am brand new and just teaching myself so it is was very helpful.