2- How to get a floor plan printout at a specific scale       like 0.5 inch on printout = 12 inches of design.

Part #1 of 2 : Searching for the maximum printable area of your printer

First, you must know the maximum printable area of your printer.  You need to find that information only once.  You can find it by doing one of these three procedures :
  1- Search for it in your printer manual.
  2- Divide the printer Image dimensions by the printer DPI currently set.
  3- Print a floor plan and measure the frame surrounding the floor plan image with an accurate ruler.

We will use the third procedure in our example because it is the quicker and easier one.

Run the Scene Editor program then click the New Scene button in the Project Selection window.

Simply accept the default settings in the New Scene window by clicking the OK button.

In the Edition Tools section click the Print Floor Plan button.

In the Print the floor plan window, be sure to select the Overprint a frame around the image button, then click the Print Setup button.

In the Print Setup window, select the printer, paper size and orientation then click the OK button.

Back in the Print the floor plan window, click the Print button to start the printing.

Take the time to do a very accurate (1/64 inch) measurement of the width of the frame surrounding the floor plan image.  By example, on an Epson Stylus Color 600 printer, in landscape orientation, for an 8.5" x 11" page, the maximum printable area is 8.2666" x 10.3333", so the width of the frame measures 10.3333" and the frame height is less or equal to 8.2666".

Part #2 of 2 : Calculating and setting the scale value according to your printer

The scale value of the floor plan represent the viewable width of the working area in the main window.  When you print the floor plan, this width always fit the maximum printable size of your printer depending of the paper orientation.

So the formula is :
maximum_printable_size / wanted_printout_scale x corresponding_floor_plan_scale = scale_value_to_set

In our example, we want that each 0.500" on the printout to correspond to 12.000" of our design.  So for an Epson Stylus Color 600 printer the solution is 10.3333 / 0.500 x 12.000 = 248.

To change the floor plan scale, click the Edit Tools button in the Edition Tools section.

In the Adjusting Edition Tools window, erase the contents of the Scale text box and type in your calculated scale value for your printer.  Press the TAB (or Enter) key to validate the entry.  Click the OK button.

Your design is now resized and centered on the floor plan, ready to be printed at the desired scale.  (This operation does not modify your 3D camera positions so you will need to readjust them.)

If your design no more fit in the floor plan working area, it is because the scale is now too small.  In such case, you need to choose another scale ratio like 0.500/24.000 instead of 0.500/12.000 in our example.

Your calculated scale value is good forever unless you change the printer or the paper size or orientation.  It is a good idea to always begin a new project with your calculated scale value so your floor plan printout will always be at the desired scale.