I've been using CC3 for the last couple of years for creating CC3 overland maps. I had the Dungeon module, but since Dundjinni has been my goto app for years for tabletop miniature/encounter maps, I haven't used it for those. Recently I discovered some building and dungeon maps I hand drew about 30 years ago, so I scanned them in with Photoshop. I was able to create some decent PNG's that I can import into CC3 as backgrounds and then trace - can only do the same in Dundjinni by treating those PNG's as resized tiles, which is a real mess. Since the original maps were building/dungeons, that got me wanting to learn about how grids and scales work in DD3.

My initial experiments with DD3 have created some some surprising results. I'm creating 34x33 maps, so that I can easily & cheaply print them out as tiled, tabloid sized PDFs at a local printer. When I'm creating the maps I'm spec'ing them as 680 Wide x 660 high using the DD3 wizard. I've then been creating a square grid without snap at a spacing of 20.0000, which is working perfect for creating a uniform 34x33 grid & the initial distance grid line -to- grid line is the expected 20 numeric units. However, I really want maps on a 1:60 scale, where the distance between grid lines is 5; as in 5 feet. Where I'm encountering weirdness is when I access File > Drawing properties > Drawing Units and set units as inches and spec 60 per while rescale is set to true. That gives me the unexpected result of 4 units between grid lines? The really weird thing is if I set set units as inches and spec 48, I successfully get my 5 units between grid lines??

I've also been setting up a snap grid with 3" spacing via Tools > Snap > Grid Settings and spec'ing Square Grid=true, Snap Divisions=1 & Spacing=0.25000, which always produces the same/correct 20 (3") units between grid lines whether I used the 48 or 60 inches when rescaling drawing units. I can live with this situation because hey, I'm consistently ending up with a grid of 5 numeric units. It's more that I'm just curious why I'm succeeding with the 48 inch spec. I'm guessing I'm doing something, but can't figure out what it is. I'm explored the CC3 user manual & in-app help, but they don't really explain this.
Anyhow - if anyone knows why I'm getting the results I'm having, I'd appreciate hearing about it.