Can't get Contour to mill the bottom, and Blend strategy is not respecting heights

[hackish]

This is a 2 part question. 
a) I can't get the contour path to machine the bottom of an arc.
I've been trying to mill the inside of this arc with a ball end mill. After roughing it out, I would like to start at the lowest Z and climb mill up the sides in a looping fashion. Contour appears to do this except it won't run paths along the bottom of the arc. 

You can see the area missed in the photo.

B) I can't get the Blend strategy to respect the height limits. I believe this is a bug.

In order to overcome the problem above, I decided to try the blend strategy to machine the small area that is missed by contour. As a method of restricting the toolpaths, I decided to use the top height feature, but the path generated attempts to machine all levels. 

[seth.madore]

3D Contour cannot do a proper job as the surface approaches horizontal. What you should do is either use Steep and Shallow (requires the Machining Extension) or a combination of Parallel and 3D Contour

[hackish]

Yes, I understand that the contour was likely limited, so this confirms the first part of the problem.

Blend should also be able to accomplish this task.

As you can see, the Blend strategy is ignoring the "Top Height." I'm sure there are kluges to work around this, but it still appears to be a bug.

[seth.madore]

No, it's that the Blend tool is still in "Preview" functionality and this is just one of the limitations for it. In reality, the tool is going to the utmost of it's tangency. If you want to force it beyond, extend your Patch surface accordingly:

 

[hackish]

I think you have the heights problem backwards. I was just trying to trick it into limiting, not extending the path to the section shown in the photo. Exceeding the height limits could be bad, and this is why I feel it is worth documenting for the developers to fix. 

[seth.madore]

OH! I see what you're saying now! Yes, this should get logged

(it appears that my reading comprehension has taken a hit today)

[hackish]

More fun stuff:

I duplicated the patch surface to limit the toolpath as discussed above. Unfortunately I couldn't get it to order the passes starting at the lowest Z point, thus optimizing the chips on the periphery of the cutter.

I separated the patch surface into 2 halves so each could be selected as a blend surface. Unfortunately it catches the fact there is an odd number of drive curves, but doesn't consider that a drive curve could be common to both drive surfaces. 

As you can see, I have busted it. I'm good at creating internal CAM errors! It think it would just be a decent error to report to the developers so they can catch it. I'll keep messing about with it.

[hackish]

Does this help the debugging?

[seth.madore]

I have logged the first issue (Blend "Height" settings) as CAM-35844

[seth.madore]

For the second issue, I believe this comes from incorrect Machining Boundary selections. Setting it to "Bounding Box" permits a toolpath with no issue:

 

[hackish]

Thanks, this is also helpful, but still doesn't really address the desired outcome in message 7. I would like to have it machine starting at the lowest Z point and stepping up. This is required in order to use the peripheral edge of the cutter. This strategy has applications on any convex or concave blend surface.

Additionally, it would be nice to have the strategy consider the distance to all other blend faces for the next segment of its cutting path. Lift, rapid back and cut the next row isn't nearly as efficient considering the adjacent face is very close and the machine could simply transit across and apply the cut on it.

[hackish]

Oops, I seem to have replied the wrong level of the thread. Just in case you didn't see a notification, my reply is below at the root level.