Subtract Solid from a Helix Sweep

[Bovine]

After creating a helix sweep (e.g. a barley twist), the ends finish at a point and I want them to be flat; perpendicular to the center-line of the sweep. I've tried using the Subtract Solids command, but always get an error saying "You have tried to create a solid object which cannot be computed."

Is there a way to "chop off" the ends of a helix sweep?

Edited March 31, 2010 by Bovine

[Kevin McAllister]

The operation fails because the profile curve used to create the spiral is large enough to overlap onto itself. In my example, I was able to subtract a rectangular solid from the thinner spiral on the right. I was not from the overlapping spiral on the left. You can, however, use the Split tool (it looks like an X-acto knife) to trim the overlapping spiral (that's how I flattened the top).

Hope this helps.

Kevin

[Bovine]

Kevin--

First, thanks for teaching me a new tool (I've been ignoring that thing for years and am now glad to know what it can do for me).

I was able to recreate splitting using the same basic shapes that you showed, so I know that I'm using the trim tool correctly. However, when I try to trim my own sweep, the computer takes some time to think about it, then simply doesn't bother to do anything (just returns me to where I was; no message or results).

Any suggestions as to why?

[Kevin McAllister]

I have found some tools can be finicky at times. I tried again with my own example and found that I had to use the third mode for the Split Tool (Trim by Line, where you select the side to keep with the third click). The second mode (Split by Line) gave me the same results as you.

I you post an example file, I am happy to give it a go and see if I can trim the shape.

Kevin

[Bovine]

Here's the file I'm currently having problems with. One warning: it's been made with the VW education license. As I understand it, if you copy anything from it into a file from any other license, all other items in that file will take on the education properties and that file will always have the VW watermark printed with it. However, as long as you keep all work isolated, you shouldn't have any problems.

Any help is most appreciated.

[Bovine]

After much experimenting, I've finally found something concrete. I think it's a problem with the relationship between the height and the pitch of the sweep. If the pitch is at least .002" greater than the height, the Split Tool works (in both Line Trim mode and Line Split mode; I didn't try the Point Split mode). Anything less than .002" fails to split.

In the file I posted above, there is an additional problem: the original polyline used to create the profile of the sweep still has the six objects used to make the polyline hidden behind. I was unable to do any splitting of the sweep until I recreated it using only the polyline (without the original objects).