Here are two pictures of walls and ceiling before starting...
The HVAC and one of the main structural beams are in this soffit. I am adding lights and making it look more integrated into the overall plan.
After putting all the layout marks on the surfaces, I started by nailing 2x3's to the ceiling . I put poly glue on these, and once in place I added 3" screws about every 3 feet. This might be over-kill, but I don't want these ever coming loose.
I like using 2x3's for this. They are straighter than 2x2's and are quite a bit lighter than 2x4's.
Once these where in, I hung OSB off of them. These are only stapled in place. When I put the sheetrock on, the nails will go through the OSB to the wood.
I needed to run the video cable (RBG) from the tuner to the projector, through the soffit. I decided to put it in a 2" PVC conduit. If I ever need to change the cable (probably to HDMI at some point) this will make it much easier. I needed to get this into place before putting the bottom of the soffits in.
This assembly is the for the bottom of he soffit. Once put together, I just slide and nail it in.
Here is one of the bottom units with the recesssed light holders in place.
Here is the soffit bottom put into place - nailed to studs and stapled to OSB.
I was able to get about 80% of this framed today. I will finished it out tomorrow and wire the lights.
Here is the final floor plan...