I had a very tight space for my turntable and roundhouse, so the template provided by Walthers was very useful for me to position both structures properly in the space I had. The turntable plus surrounding tracks can take a lot of real estate… I installed the turntable first, then the roundhouse, then I adjusted the tracks while the roundhouse was still floating on the layout. My margin of error was only about 1 inch, so it was crucial for me to plan it correctly. I programmed the turntable, and when I was satisfied with it, I nailed the tracks to stabilize everything. That was three years ago - no problems since.
Sure but in order to locate the position of the turntable you must first know exactly where the roundhouse is to go. The issue is locating the centre of the turntable before you “position” it. Obviously you cut the hole for the turntable before you secure the roundhouse in position. But you use the roundhouse position to find the position of the center of the turntable before you cut that hole.
And that is where the Bat-0-template works well, incorporating the printed Walthers template. You can move it all over the place and when you’re ready put a pinhole through the centre of the TT to mark the spot.
