Tutorial: Using Avoidance Geometry
- Kevin Strider (Unlicensed)
Avoidance geometry ensures that machining operations do not occur in specific portions of the stock for the selected setup/workpiece, such as the space under the part or between the vise jaws.
These blocked out portions (Avoidance geometry) are different from fixture bodies. While fixture bodies MUST be avoided, the Avoidance Geometry is considered part of the stock and may be gouged in the case of ‘hole making’ operations. For example, drilling a through-hole may pierce the avoidance geometry but not the fixture.
Fixture bodies also require clearance from any tool, whereas all roughing tools may touch the surface of the Avoidance geometry.
To magnify any image or screenshot, click on it.
Avoidance Geometry options
The Avoidance geometry feature is available for each ‘Machine Group’ within the ‘Setup orientation’ section of the General tab, as shown in the image to the right.
An important point to note is that using Avoidance geometry is completely optional, you could take either of the following actions:
Specify avoidance geometry for any of the Machine Groups that you have checked.
Don’t specify Avoidance geometry.
If your part/model does not have a defined avoidance geometry body, then you will need to create it before you can use CAM Assist’s Avoidance geometry function (see the example, below).
Using Avoidance geometry
The example used in this tutorial (Avoidance Geometry Example.mcam) has a defined ‘Avoidance geometry’ body, which is a portion of the stock.
To use Avoidance geometry, take the following steps:
Check the relevant Machine Group (see the example to the right).
The 'Select avoidance geometries’ button (shown in the image to the right) is used to indicate that you want to specify the relevant portion of the model within Mastercam.
The number in brackets shows how many selections have been made.
Within Mastercam:
When you click on the model, the selected body is highlighted (as shown in the example, below).
Within CAM Assist:
Two things happen after you’ve clicked ESC (as shown in the image to the right):
The ‘Select avoidance geometry (0)' button is updated to show the number of selections: in this case, it is updated to 'Select avoidance geometry (1)’
A new button, ‘Clear selection’ is displayed.
Click it to remove all of your avoidance geometry selections for the associated Machine Group.
On clicking 