I thought snap to grid was supposed to help me align architecture pieces (ie like they snap next to each other) but all it seems to do is make the object move in bigger steps, making it impossible to align the pieces most of the time. what's the point of this feature?

When designing a large interior, to align the architecture pieces (like hallways, room pieces, doors etc) i often end up having to enter the coordinates manually because they don't precisely fit when i just move them around with the mouse and use the XYZ keys, doing that for every piece is time consuming.

Is there an easier way, or have any of you some helpful advice on this?

Also, is there a way to lock a specific piece of architecture to certain coordinates? like, locking it's X axis position but still being able to move it along the Y axis? (aside from holding the X button)

Make sure you've selected a reference to snap to- that way the grid will be centred on it.

Also, if you want to move it on X, look down at it in the window.

how do you select a reference to snap to? by pressing Q when selecting that specific piece and then selecting the other piece that you want to move and moving it to that piece? i tried it, but it was still a little off

The snapping functions do work. If your pieces aren't lining up, then jiggle the ones you're trying to snap to, they were probably placed non-snapped.

Also note that not ALL pieces fit the same 256/128 unit grid, but lower snaps may work.

The only real difficult ones for me are the ones that are multi-level because you can't see the connectors clearly. The "vault armory" and "overseer's office" pieces are really difficult for me to place properly, especially when you have a door there, it's hard to not have the door controller floating midair or a gap in the map. Lucky for me I'm using both in one vault!

I find that 32-unit snaps help with some of the difficult lineups using "special rooms" that are one solid block.

Yeah, the tunnel under the overseers desk doesn't grid-up if I recall and unfortunately for me that's where I was putting my player house (Overseers' apartments). It didn't help that I was also fudging certain things with manually-built sections out of single-plane tiles, some of which were crazy offset from their center due to what they were originally used for (Take a look at NVLucky38RmHiMidFloorOnly01: nice piece but 256 units offset on Z for some reason, not that bad. NVLucky38Rm2xMidFloorOnly01: 38 units offset on Z :| NVDeathFakeWallTopPiece: I dunno how offset, NOT SQUARE and x/y NOT DIVISIBLE BY 128/256 >.<)

I ended up positioning lots of elements with 1/2/4/8 unit snaps and the reference properties window