I figured out a slightly laborious, but effective and free method for making nice square-to-round transitions. This is especially useful for the Nike Hercules transition section. The steps are as follows:
1. Go to http://www.sheetmetalguy.com/transition.htm and enter the specs for your transition. You will need Internet Explorer to generate the output file. The file is created as .txt, but is actually a .Dxf file and needs to be renamed with the Dxf extension.
2. Download and install the free Google Sketchup 8. http://sketchup.google.com.
3. Download the free Google Sketchup 8 dxf importer plugin from the Sketchucation forum (requires registering a free account). Copy the file into the Google Sketchup plugins directory.
4. Open Sketchup, import the Dxf file you created from the sheetmetal guy site.
5. Adjust view.
To change the view for our purposes, click Camera, uncheck ‘Perspective’. Then mouse over ‘Standard Views’ and select ‘Top’.
This will give you a perfect top-down perspective. Make sure to adjust the window so that all edges are showing, otherwise it will be clipped when printed. Also, move the model to the top or bottom of the window. This might help minimize the number of pages it prints on, or that you’ll need to cut and piece together.
Before printing, make sure that ‘Fit to Page’ and ‘Use model extents’ are both unchecked. Also under Scale, set ‘In the printout’ and ‘In Sketchup’ both to 1.
6. PDF generated using this method for the TLP Nike Hercules plans. (This transition is what I got stuck on the last time I worked on it.)