Blum also has a very adjustable rail hanging system that is fairly easy to incorporate into your cabinets.
If you build your uppers with a 1/4" back with nailers, then you can route a space for a 1x4 to sit under your nailer. This is how I typically hang my uppers. I can do all the prep work of fixing a 1x4 exactly level, and screw all the cabinets together I can, then just need a hand to lift the cabinets up on to the wall until I get a screw or two in. Doing it this way you will find it way easier to get everything lined up and installed with a minimum amount of fuss, and perfectly level and without any distortion of the boxes. When you pop the doors on, you will be amazed at how easy it is to get all your doors closing properly and the reveals right.
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