"
i don't undestand the usefulness of a pattern in a 3d offset stgrategy.
In my example i need to create a 3d offset that goes from inside to outside."
So to me this is two questions
1)I don't understand the usefulness of a pattern in a 3D offset strategy
2)In my example i need to create a 3D offset that goes from inside to outside
2) I will answer the second one first. In PowerMILL 2017 there is a new control to start outside, so I am assuming you are using an older version. The easiest thing is to simply do a "reorder". So you create the toolpath like normal (with or without a pattern see answer one) and it is starting outside as it always does with 3D offset. So you Right click on the toolpath and select EDIT then REORDER then in the reorder dialog select REVERSE ORDER. This will take the toolpath and change it from inside to outside. As a tech tip you may need to create the original as a conventional cut so when you reorder it it converts to climb if that is a factor. Easy as pie and no need to recalculate the toolpath. BTW this works on almost every strategy if needed
1) So the second question is what are patterns used for? This is a more abstract use and probably not used very often depending on what you are doing. Typically when using 3D offset you have a boundary and the toolpath starts on the boundary and collapses in a 3D offset manner, as you expect. What a pattern allows you to do is to direct the toolpath to follow a different cut direction or offset rather than simply using the boundary. Like a middle out approach, or typically using "open" offsets versus the "closed" offsets you typically get. Hopefully that answers that.