Jan, I could be wrong, but I think he might already have the engine and that's why I'm trying to fit the 34" turntable. Here are some things I found this morning.
Here’s a link to another thread with a setup similar to the one he’s trying to emulate. Unfortunately, it doesn’t provide any dimensions or specify which turntable was used. However, the specs in this link say the 3-stall Korber Model 304 roundhouse footprint measures 15” across the front, 28.5 across the back and 30” deep. This link says the footprint for a single stall measures 5" across the front, 9.5" across the back and 30" deep. This link says the Big Boy extension measures 9.5" across the front and 6.5" deep making the overall depth 36.5". Put all these together and you get a footprint for a 5-stall roundhouse with 1 space for a Big Boy that measures 25" across the front, 47.5 across the back and 30" deep with at least 1 stall being 36.5" deep.
So, I created a polygon that measures 5" x 30" x 9.5" and duplicated it 5 times. I added the Big Boy extension to the middle stall and then tried to align it as close as possible for the tracks to be in the center of each stall. This is what I ended up with.
One of the photos in the links shows the roundhouse positioned 16.2" from the turntable and that is the length of the first track in each whisker. As you can see, I had to go to about 20" to get close to centers for the engines. I can't tell from the photos in the links which specific turntable they used. The SCARM default has 48 positions at 7.5°, but I tried the others and still can't match the photos.
The bottom line is I don't think this is going to fit unless the coaling tower is moved or the turntable is separated from the roundhouse and that impacts the space for the yard. He might have to live with a smaller turntable with just a parking space for the large engine. I've attached this test file if you want to double-check my work.
