Massprop Help please

[cchallis]

im trying to get the engineering properties of a custom extrusion.

i know how to create a region of the polyline and then use that to get the data, however this perticular extrusion has 2 holes in the middle of it (3 closed polylines in total) however i cant create a region out of 3 polylines, in which case i cant get the data out of the massprop.

i beleive there is a way of creating a 3d solid to do this but i cant get to give me the correct properties as adding depth "Z" to the object changes the properties and dosnt apare to give me the correct data set.

ive tried using a 3d surface (dosnt work)

and ideas people??
im sure this has been done many times before.

cheers

[jaberwok]

The big question is - why can't you create a region from 3 polylines?
A region can have multiple holes without problem.
Can you post the polylines here?

[cchallis]

I’ve worked it out.

Thanks for your reply, but in the interim I figured out what I was doing wrong.

I didn’t really know you needed to treat a region as a 3d object.

In which case by creating a region of the whole extrusion then using a subtract command on the remaining polylines I successfully created a region with holes in it.
I don’t quite understand why AutoCAD can’t just do that anyway, but no matter as I have it sorted

Thanks again. Look forward to my next technical difficulty!!