I've been doing some research... specifically if I use 4x4 posts to replace some 2x4 beams to allow for bigger cabinet doors.
So far so good when it comes to the news on it. Found out it would be similar to building a deck. Same properties exist. 4x4 post to hold 2x4 beams, to support mass amount of weight. However nails and normal screws wont work to attach the 4x4 to the system. I'll need carriage bolts (4"x3/8" bolts with nuts and washers). They'll act as a joint and will support it more so than the beam.
However I'm also looking into Lag bolts as I wont have to pre-drill the hole for the carriage bolt that will need a square entry point.
Lag bolts have some great properties...lol http://i56.photobucket.com/albums/g166/jraabe/bolts.png
If i use a 4x4 and mount 2x4's onto the side of it, using a 3/4 inch bold going in all 6" would be over 1000 lbs of weight that one bolt could hold.
However I'll probably go with a 1/2" going into it 4"... so the 2x4 would be on the 4x4... the bolt wold reach 1/2 way into the 4x4.
With that said if I have 6 posts, one on each corner, then two in the middle that should allow me to obtain maximum hold. Regardless with that said, I'll be adding tons of support beams with regular screws along the rest of the system for added support and safety. But this will allow me to maximize entry doors into the bottom half of the unit.