Aid with simple spline loft

[cc01720]

Hi,

I am looking to create a loft between a circle and a point but I am having trouble with making the spline a rail:

Sketch1 is the spline. I used two coincident constraints to constrain the circle to the upper and lower points. I think it might have to do with the work plane offset constrained to the upper point only. Perhaps I have to constrain the work plane to both the upper and lower points? Not sure how. 

Part attached.

Thanks!

[cadman777]

Maybe try:

1. locate the WorkPoint directly on the spline inside the Sketch, instead of on the spline's control point.

2. split the spline in half at the apex, and make 2 halves for the spline in 2 separate Sketches.

3. delete the line going through the diameter and use VerticalConstraints to align the end points to the origin. Then put a SketchPoint on the ends of the Spline to Project in your circle sketch for locating the circle's edges. Then use a VerticalConstraint to constrain the circle's center point to the Projected SketchPoints. That cleans up the sketches.

I'm using IV2010, so I can't use your spline. Can you send the point data you use to create it (lotta points!)?

See attached example.

Note: The Spline in my version of Inventor may differ from yours.

[cc01720]

Still giving it a go myself

And of course! I have attached the points

[blandb]

I wonder if it has something to do with the bottom curve being made up of multiple non-tangent curves? Below is just extruding and looking at the curvature of the bottom face:

Looking at the sketch spline segment curvatures:

Zooming into where 2 segments meet:

[cc01720]

When creating the spline curve, Inventor seemed to automatically complete the spline at those points that you mention - the multiple non-tangent curves is not intentional. It's probably my mouse, but after multiple retries I cant seem to get it to be one curve.

I'll try another mouse

[cadman777]

I think you are using a ControlVertexSpline instead of a CurveFitSpline (like mine is).

Try changing splines.

Maybe you need a spline perpendicular to the spline you already have to 'round out' your cone shape?

Find attached a model based on your point data to see what I mean.

[cadman777]

Find attached another model with 4 control curves.

To make the new curves, I did this:

1. copy each sketch and place it on the proper origin plane.

2. RMB on each sketch and EditCoordinateSystem to get the curves to rotate into the correct position.

Then I just added those curves to the Loft.

You'll notice that the final shape is a bit sharp along the curves near the top 1/3 of the model.

Is that intended?

One thing I forgot to mention is, I made all the spline ends that touch the circle tangent to the  plane the circle is on.

Also,  I made all the spline ends that touch the top vertex tangent to the  plane that SketchPoint is on.

That smoothed out the ends a bit.

You can also play with the Loft>Conditions tab settings to see if that helps smooth out the shape.

But since there are so many vertices, I couldn't get much of a change in tangency and smoothness than already exists.

[cadman777]

If you have a lot of points (like in this example), here is some additional info about automatically making splines with imported points from Excel:

1. Message 3 of 4 has a link to a VBA app.

2. That takes you here. Go to the end where the heading says 'Download' and download the zip file.

3. Near the bottom of the page you will see 'Notes'. If you get a 'runtime' error, then this is the KEY to fixing it:

1. Current version has a reference to Excel 2002 XP Object Library (supports also higher versions). If you are using a different version of MS Excel (and getting Private oExcel As Excel.Application error - 'Project or Library not found'), you can change your Excel library using the following procedure:
   1. Go to Visual Basic Editor (Tools>Macro>Visual Basic Editor)
   2. In the VBA Editor select Tools>References
   3. In the Available references list unselect Missing: Microsoft Excel 10.0 Object Library.
   4. Select the Microsoft Excel Library according to your installation (either 8.0 or 9.0 or 11.0) - do not select multiple Excel libraries
   5. Close the References dialog with OK button.
   6. Save the updated version of the macro

4. This is where I learned how to do the above instructions on a newer version of Excel.

Pay attention to Messages 3 of 7 & 5 of 7.

5. Once you add your Office and Excel libraries, the app should work. It works for me but I'm still learning how to use it. It's amazing when you have a lot of points to connect SplineKnots to! A gigantic THANK YOU goes out to the guys who wrote this app!

Find attached another version of this w/2 extra guide curves. I used the ImportCoords app and it took around 10 minutes to do the whole thing.