Retract Points and Limits

Enter a check mark in the two check boxes as shown in the picture below.

Now use the mouse to select the values shown in the window below.
In order to do this you will have to use the different kinds of snaps.
Here the snaps for Grid and End Points are selected .
If you cant find a way to select these values with the mouse you will have to enter
them by hand.

Now ensure that 'single step' isn't checked and select the front of the parts with the arrow pointing up.
When this is done the whole part is selected from right to left. Since we wont machine the back of the part
you should press the back button twice to limit the operation. Now the window should look like the one below.