Creating an Arched Doorway / Curved Entrance

To create an arched doorway in KD Max V10, start by creating a Decorative Panel & changing the location in the bottom right to - Free Orientation (by surface)

Then right click the panel once placed and select Change Size 

Adjust the panels size depending on your wall thickness, ceiling height and how wide you'd like it to be, then click Ok.

Click on the Panel tab at the top of the screen, click on Edit Panel and then select Make Hole 

Now you'll start drawing the cut out of your arched doorway, first click on the bottom line of this grid to select your starting point, then click the second point on the grid of where you'd like the arch to begin.  

Now click on the Arc option under Line Mode 

Select the next point int the grid to create your archway, as shown below, going 1 line down from your archway beginning point creates a nice arc.   

Once your arch is created, click on the Line option under Line Mode, then draw a straight line to the bottom of the grid, then finally, connect your cut out to the starting point as shown below to create the hole. 

If the hole is properly connected it will then turn into a red outline instead of yellow, click on the OK button in the bottom right to complete this hole.

As shown below, the above process creates a nice archway for an entrance or doorway.