Jan/Bob/Carl/Anyone, something's been bothering me and I think I know what, I don't think I created the Altoona model correctly. I think I mistakenly used the Korber dimension for the back wall and that means the stalls are wider than they should be. Here's what I'm working with, so please tell me where I'm going wrong.
First up is Altoona.
They sell a 3-stall base kit, but don't provide all the specs for it, so I had to extrapolate them using the specs for the 5-stall examples on their site. The example for the 55" version says the front wall for each stall is 14" from a 30" turntable and 15" from a 28" turntable. It doesn't show how wide the front wall is, but it does say the rear wall is 39". So, I had to further assume that the rear wall for each stall is 7.8" (39/5) and 3 would be 23.4" (7.8*3). It also says the length of the side walls is 26".
To create a single stall, I started with a 28" turntable with 36 positions. I placed a 55" line from the center of the turntable to the right.. I added a perpendicular 7.8" wall to the end of that line and centered it on the line. I drew 2 more straight lines from the center of the turntable to the top and bottom of the wall. I placed another shorter wall 15" from the center of the turntable to complete the stall. This resulted in a polygon with a 4" front wall, 26" side walls and a 7.8" rear wall. I duplicated the stall to make a 3-stall version and the basic dimensions become something like 12"F x 23"B x 26"L.
When I positioned it over the original turntable and whisker tracks, I noticed the whisker tracks no longer were centered in the stalls because the new stalls were narrower. I expected this. Initially I replaced the 36 position turntable with the 48 position turntable and noticed the whisker tracks were closer to being centered, but not quite there. Here is where I discovered something interesting,at least to me.
I deleted all but 1 whisker track and duplicated it. I then selected the duplicate and the turntable. I rotated both until the whisker track was centered in the upper stall. I then repeated the process for the lower stall. When I rotated just the turntable back to its original position, I noticed all 3 whisker tracks were connected to new "indexed" positions on the turntable. When I double-select the turntable, the connected whisker tracks get selected too. I did not expect this to happen. It tells me the displayed position points are not finite. In the photo, you can see how the whisker tracks are connected and the other positions based on 48 are still displayed. You can also see where the other whisker tracks connected to the 28" turntable with the original 36 positions.
Bob, please note that I understand indexing, until now I just didn't know how to deal with it in SCARM since the turntables all have set position points.
Another thing to notice is that I changed the track display to display the rails and not the footprint with ties and roadbed. This is because when I used the footprint display, they overlapped each other since the whisker tracks are now closer together. If you look closely at Tom's photos, you can see where he trimmed the roadbed. Thanks again for the photos, Tom.
Now you may ask what is the point to all this? Well, in addition to having a more accurate roundhouse to work with, assuming my methodology is correct, it may be possible to add 1 or more stalls. I noticed a note too on the specs sheet that a front extension couldn't be added to this configuration. I still need to figure out the 63" version, but I believe it is the 55" version with the front and rear extensions added. Since 55+6+3=64, presumably it's able to be placed 1" closer to the turntable, but in this case it has to be the 34" turntable or the engines won't clear the doors. I really hope someone checks my methodology. Hint-Hint. 
Now for the Korber.
I never looked past the Model 304 on the Korber site, so I never saw the Model 320. In any case, Korber makes it easier because, unlike Altoona, they provide the basic dimensions. The 304 is 15"F x 28.5"B x 30"L and the 320 is slightly smaller at 15'F X 25"B x 26"L. Both are wider than the Altoona and increases the angle at which the whisker tracks have to come off the turntable in order to be centered in the stalls.
If you study the Korber schematics, they seem a bit confusing, at least to me. I can see how they're trying to show the effect of moving the roundhouse closer to the turntable. They show that even with indexing, the whisker tracks come off the turntable at different angles that may clear the door, but won't be centered in the stalls. It says that the roundhouse has to be 16.2" from the turntable for things to work correctly.
This is where I run into some trouble. Jan's diagram shows there is a difference in how far each model has to be from the turntable. However, once again the numbers don't seem to match. Using the numbers for the 304, Jan's photo shows the distance from the center of the 28" turntable to the front of the roundhouse is 27". This means the front of the roundhouse is 13" from the edge of the turntable (27-14) while the schematic on Korber's site says it has to be 16.2". The schematic also says the length is 59.7", not the 56.25" in the photo. This is explained by the difference in distance from the turntable and I suspect the engines might not clear the columns between the doors if it's set to close, hence the 16.2".
I don't have time tonight, so I'll fiddle with this some more tomorrow.
