Didn’t seem like we could reply to the OP so I have opened this thread here for anything anyone wants to discuss. I have a couple questions/points to think about.
Biggest thing that hits my mind is that the vacuum hold down is only effective if the vacuum board is not damaged. The amount of eating into the spoilboard we see currently on the machine will absolutely cause problems. Any crack allows the vacuum to escape, you want the surface entirely flat. This was an issue on the Multicam CNC at Dallas Makerspace, and eventually we ended up completely redoing the surface and instilling strict rules about using additional spoilboard layers and penalties for damaging the vacuum board.
Here is a thread about the process we went through with installing and sealing the new bed. One great feature that was added in this update was dog holes.
You can see them in effect here. They are set so that when the metal dogs are in place, the corner of the spoilboard is at (0,0). This allows for super easy repeatability and really precise work. Currently you need a good amount of slack on either side of your piece in case you didn’t position it exactly right, and if you realize after trying to assemble something you made a mistake you are SOL. With the dog system, you can simply place the piece back onto the CNC and remove more material. This also allows for use of jigs like the one shown for cranking out pieces with great precision. It’s a fairly easy thing to add, completely optional to use, and extremely powerful for those who want to make use of it.