[67Cuda]

When using V25 3D mill,as far as I can tell, you need to free hand or use a sketch shape to create a boundary to contain a tool path on a solid model.

Is there a way to select a boundary of off the solid model directly by using a surface?

Is there an accurate way to select an edge off of the solid model to create a sketch for a boundary?

Or are boundaries just a kludgy way to contain a tool path with no real precision when using 3D mill?

Tom

[bobcad guy]

you can precisely draw any shape as a containment area. if you want to take geometry from the model, maybe you might want to make it a wireframe, copy the lines in the area you want to use as containment, translate them to say an inch or so above the part, trim off any excess lines, and that should do it. if you have sorins videos, I believe he addressed this very topic, maybe not as thouroughly as you want, but it should help.

[RAF.]

I have noticed when using a boundary with 3D Equal Distance Offset with flat top parts it seems to work best for me if I offset boundary smaller1/2 dia of cutter

[Ben S]

The center of the tool will go to the boundary you select. Like bobcad guy says, you can draw any shape. I believe you can also select the surface of a solid part.

[mcphill]

I like to extract edges from the model on to a new layer. Then create a surface above the model (on another new layer). Finally, project the edges from their original location and changing Z heights on to the surface (on the edges layer or on a new third layer). This results in a "flat" drawing of the extracted edges where funky changes in Z height are eliminated. Now start trimming edges and corners on the flat shape, so that if in the end you can select the whole boundary with a single click. If you leave a bunch of overlapping lines or gaps in the boundary, the toolpath can fail or take forever to complete. By having a clean boundary, you are ensured a smoother process. Also, by having it all contiguous, it is very simple to offset the boundary (inward or outward, depending on need).

[Malish]

I usually use extract edges from the solid model like Mcphill said. Putting them on a different layer makes them easy to pick and/or turn off when not needed. This works well when your surfaces are flat or only changing in 2 directions.

If you have to follow a totally 3D surface I usually add extra surfaces to follow. It's a little more work, but can sometimes help out on tough parts.

[67Cuda]

Thanks for the advise guys.

I tried extracting to a new layer and it works great! Things have just gotten easier.

Tom