Profile - free curve between floating curve and tangent

[jameshitt]

I must be missing something. I have a profile with a floating curve, and a fixed tangent, with a gap between them. I want to fill the gap with a free curve, but every time I try, I get "No solution available"

The proposed radius for the free curve I'm trying to create is also 30', the same as the floating curve before it, and I am absolutely certain that the curve will fit where I'm trying to create it. But I only get "No solution available" (which just seems absurd).

What is going on with this?

[jamesmac1201]

Are you able to share your drawing?

[jameshitt]

Sure, here it is.

[sboon]

Interesting.

Apparently the software cannot add a floating circular curve from a tangent and it cannot calculate a free circular curve that intersects a floating parabolic curve.  I also found that it won't accept a radius as a parameter for inserting the free vertical curve but it will allow me to use a pass through point and then adjust it until I get the radius you wanted.

[jameshitt]

Thank you for confirming what I feared.

Is it me or is it not bewildering that the profile geometry tools seem to be pretty much broken?

[sboon]

I wouldn't call them broken, but they have not changed much since the first full version of Civil 3d back in 2006.  Very few people use circular vertical curves for design so issues like this one are rare, which means that Autodesk does not put any effort into this problem.

[jameshitt]

I do not accept this explanation from Autodesk. This seems far too basic to not include after 16 years of Civil 3D. Maybe I am only seeing it from a narrow perspective; but in my case, yearly I might see half a dozen or more directional drilled water/sewer utilities like this which require reverse curve offsets.

[jamesmac1201 · Accepted solution]

So try this method. I got it to work..

1) Go to Profile Layout Tools and select "More Free Vertical Curves....Free Vertical Parabola (PVI Based)

2) Select near the PVI and select a small vertical curve length. I selected 10' to start off with

3) Select Profile Grid View to bring up your Panorama

4) You'll see the curve you add plus the two that were already created. The two that were already created will have 30' for the Curve Radius (and 0.30 for the K value)

5) Change the Curve Radius to 30.00' to match the other two. YOU WILL HAVE TO DO THIS MANY TIMES FOR IT TO TAKE.

a) for example after I typed in 30' and pressed enter, the value changed to something like 35.94'. Just keep changing the value. It took about 6 or 7 changes to finally take.

[jameshitt]

That is a workaround I never would have even imagined. Thanks!

Wow, the behavior of that radius setting getting closer and closer to 30 (and on what seemed like a kind of curve, the change getting smaller at a decreasing rate with each iteration) is one of the most bizarre things I've ever encountered in CAD. Most CAD bugs, I just want them to go away as soon as possible, and avoid at all costs. But this bug has the distinction of being seriously interesting!