Skin function

[sheldon@dingwallguitars.com]

I am having trouble getting the skin function to do anything useful in version 8.

When I follow the proceedure layed out in the manual or help file, the skin function is either greyed and not useable or creates bizarre tool paths. I'm using arcs for cross sections and paths.

[Support (Admin)]

Comments on the original question about using the skin function would be welcomed.

[gordon@shopbottools.com]

Sheldon,

The rules for skinning are fairly easy once you understand them, but I struggled with them myself until I fully understood how Vector wants things. Here are some things that may help you with skinning.

First, a skin is made up of 2 parts that represent the cross sections of your part. If your part were a grid then you may look at it like you did a grid in geometry class with one direction represented by m number of sections and the other n. Each m number of sections must have the same number of elements in each section and each n number of sections must have the same number of elements in its sections. For example when you select the horizontal lines for the 1st set of sections (the path), then each must contain the same number of elements. This doesn't mean that the path sections and the skin sections have to have the same number of elements. Say you selected the path sections and they have 14 elements in each and the skin sections have 17, then you are alright, but if some of the path sections have 12 and the rest have 14 the skinning function won't work. TO check the number of elements in each section, select each section on at a time and click on Special->Verify. To make the number of elements the same you can break or interpolate each set to a number that works for all of them.

The next important item is that the sections must intersect with each other. In other words, the m sections and the n sections must touch each other at there intersecting points. So, the end points of the path sections must touch the first and last skin sections, and the end points of the skin sections must touch the first and last path sections. Also, where the path and skin sections overlap they must also touch each other.

When selecting the sections that make up the path section you have to select them in a logical order and then the skin sections in a logical order the coincides with the path sections. Let's say you select the horizontal sections starting with the one farthest away from Y zero and its arrows running towards X zero. Then you select the rest in order with each ones arrows facing in the same direction and then you make this the path with the 3D->Path command. Now, select the Vertical lines starting with the section farthest from X zero and its arrows toward Y zero. Then, select the rest of the vertical sections in order until you come to the one closest to X zero, all with their arrows running towards Y zero and skin with the command 3D->Skin.

"Why is my skin function greyed out?" is a question I've heard a lot. If the skin command is greyed out then something is wrong and you need to go back and check to make sure all of the issues above are satisfied. Either the numbers of elements aren't the same or the sections don't intersect or the order of selection wasn't right.

If all the things above are correct then after clicking on the OK button for the skin function you should have a series of tool paths running in the same direction across your part. To get this series of paths into one tool path that can be output for cutting you'll need to do a few more steps. With all of these lines selected in the order they were generated in click on Special->Reverse every 2nd and the Draw->Line->Connect. This will do just as it says, reverse every other tool path and then draw a line connecting the ends. The last thing to do is to Chain Connect them with Retraction using this same command. Use either Draw->Other Curves->Connect at Z or the 5th button from the left on the CAM toolbar.

One last thing that may help if you're using arcs and those in one direction or the other touch at their ends then you'll need to put a gap between them and add a path or skin section in between. For example: if you are making a round path made up of 2 arcs, then you can double click on these arcs and change their start and end angles putting a 1-2 degree gap in between them. Then, add a skin section in between the end points.

[imserv@imsrv.com]

"With all of these lines selected in the order they were generated in click on Special->Reverse every 2nd and the Draw->Line->Connect. This will do just as it says, reverse every other tool path and then draw a line connecting the ends."

Use 3D-Connect for a similar effect without requiring the reverse every second step. The primary direction between the two methods will be perpendicular. That is , with 3d-Connect the first cut will be parallel to the first path selected, whereas with the Reverse every second and Line connect, the first cut will be parallel to the first Section selected. If you use the Reverse every second method, make sure to set an appropriate max length when setting the path, as the stepover in the skin dialog is ignored with this method.