Quote Originally Posted by JRDM View Post
"Instead of having the extruder, which is where the build material is expelled from, move on all three axes, they have changed the mechanics around quite significantly. The MOD-t 3D printer will feature an extruder that only moves in the Z direction, while the build plate will move in the X and Y directions."

The MOD-t movement isn't special. That's how a "knee" or quite a lot of vertical mills are setup. The down side with how they show it is that the machine envelope is needlessly large, or it further constrains the XY build area.

I don't know what cartesian 3D printer moves the extruder in all three axes. Maybe it's common in the big-name high-dollar machines. A Mendel-type is often set up to move the extruder in the XZ axes, and moves the table in the Y. Makerbot & Ultimaker move the extruder with an XY gantry, with a Z platform moving.
True enough - the Mod-T isn't particularly unique because of which axes move the table and which move the extruder head. It's unique because the X-Y mechanism is incredibly minimal (see my early posts in this thread), and the only thing that moves at high speed is the build table itself. This both reduces the part count and reduces the amount of moving mass because the table is very light. The lower moving mass further reduces the cost of motors, motor drivers, power supplies, etc..