Using Splines for Boolean Cuts
 
Making the Cookie Cutter
Page 1
 

Many people have asked how to cut windows and doors in an object. Some say to use a shape merge method, but I find this does not always work. In this tutorial I will describe my method of doing this which seldom fails and gives me a great amount of control. It is a 3 step method and consists of making a cutter, the actual Boolean and finally the cleanup.

In this demonstration I am going to cut a flush door in the side of a cylinder

I have made a simple plane object 25' x 10' and mapped a background image that is 128 pixels by 256 pixels to it and offset it back out of the way. In the objects properties, I unchecked the Show Frozen in Gray and then froze it.

Next I made a cylinder to work on. It is 5' in diameter and 25' long. with 24 sides and a single segment. In its properties I have made it See-Through so I can see the image behind it.

In the viewport settings I have turned on Edge faces and turned off Use Selection Brackets under Configuration..

 
Now I am ready to start making my cutter. Click on the Create tab of the Command Panel then on the Shapes icon. Select Line and draw a line approximating the doors shape. When you get back to where you started you will be asked if you want to close the spline, select Yes!.
 
Now change to the Modify panel and right click on the Line and convert it to and editable spline. My Mesh Settings for the spline are 0.001' thickness, 3 sided and 0 under Interpolation. As simple as you can get.
 

Next I made another cylinder 0.25' in radius to use as a template for my corners. Moving it so that 12 o'clock and 9 o'clock just touch the outer edges of the door on the background.

In Point sub-object mode I inserted 2 points in the spline and with 2.5 vertex snap on, lined all of the splines corners points to the radius of this template cylinder. This was repeated for each corner to give me a total of 16 points on my spline and nicely rounded corners. Then the template cylinder can be deleted as my "shape" is finished.. .

 
 

While it may not be necessary, I have this thing where I like to have my objects with their pivot centered and aligned to the world. So I go to the Hierarchy tab and center my pivot point to the object and align it to the world. Reset scale and transform and apply an X-Form Reset from the Utilities panel and collapse the stack on the spline.

Now I clone the spline and move the original outside the surface of the cylinder leaving the clone back at 0.

 
 
 
Next with the original selected click on the Attach Mult. button.
 
In the dialog window that pops up select the clone and then click on the Attach button. Now both splines are one object.
 
Back in the Modify panel add a Cross Section modifier.
 
Nothing real special here, just make sure the Linear button is selected.
 
Next add a Surface modifier.
 

The image to the right shows the setting I use for this modifier.

This actually concludes the making of the cutter. If you save the "cookie cutter" in a file by itself, you can save having to make it again the next time you need one by simply merging it in to your next project that needs one. The other thing about using this type of cutting parts is that you can easily change the overall dimensions by moving the points of one side in or out or the top or bottom points up or down or even change the depth by moving all of the points on either end. So long as you don't scale the object as a whole you will retain the corner radii. Anyway now would be a good time to save the project. Next we will do the Boolean operation itself.

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