Another Boolean Difference question

[womp_1FDJBL]

I have been trying to create arched windows using a "template"

When I stick the template onto a large box, highlight the large box, then highlight the template and click on Boolean Difference

both units, box and template,  just disappear.   Looking at many Youtube  videos using this method works. 

Can you tell me why both units,  the large box and the template both disappear....please?

[trevor.adams]

Hi @womp_1FDJBL,

Can you share an image and/or scene file demonstrating the problem.  Typically, when both Boolean operand objects disappear after running a difference operation, that's usually because of how the objects are placed in relation to one another, or that one or both objects are open-form instead of closed (a plane vs. a sphere, for example).  In the latter case (open form meshes), you'll want to use Edge Intersection Classification (this is the default anyway - found in the Booleans options window).  Have you tried setting Intersection Classification to Normal?  Again, if I can have a look at the objects you're trying to create a Boolean Difference for, I can better dig into the cause of the disappearing objects.

Thanks!