Here is a desktop sized CNC machine called blueChick. It really does fit on a desktop, with not much else on the desk. The machine measures 20.5" wide and 40" deep. The total routing area is 13" x 24" or 13" x 36", whichever kit is selected.
The entire machine was design with compactness and rigidity in mind. So, lets go over some of the features. First you will notice that both the x and y motors are in non-traditional locations. When the drive mechanics change from lead screw to a pulley or chain, there is no reason for the motors to remain in the same positions. The y motors is centrally located behind the z-axis which removes it from the overall footprint and does not get in the way of the z-axis motion. The x-axis is completely hidden underneath the machine. If you look closely, you will see the pulley and timing belt just outside the gantry side, the motor is actually mounted onto the gantry side and uses its dual shaft (the shaft sticks out of both ends of the motor housing) to first drive the primary pulley and coupled to a shaft to the pulley on the other x-axis gantry side. This makes the x-axis and perpendicularity rock solid and will always stay square since both x-axis gantries are totally tied to each other with a single shaft and only requires one motor for the x-axis.
Includes structural Parts (all parts including the x-axis table); Parts are made from high quality and strong MDO Plywood; hardware (nuts, bolts, screws, cross dowels/barrel nuts, washers, etc); mechanical Parts (rails, v-groove bearings, lead screw for z-axis, antibacklash nut, bearings and collars for lead screw, timing belts, drive pulleys, couplings, etc.).
Speaking of rock solid, there have been some structural improvements for this little CNC machine. Look closely again to the gantry side and you will see another MDO piece fastened to it and the horizontal rail support. This keeps the side to side flexing to a halt. I tried with all of my strength to rock the gantry and no flexing or wiggling occurred. Another structural enhancement is the y-axis rail. The vee groove bearings for the y-axis rail so not have the flexible positioning adjustment. For the sake of reducing maintenance and rigidity, I transferred the adjustability from the rail instead, which is much easier. The table is also much sturdier with linear structural members underneath to keep the table nice and flat. The machine keeps a very small footprint and has been overwhelmingly structured to be very competitive in the small CNC market, especially with price.
Check out this customer's build of his own blueChick.
The computer and router is not included. I recommend the Porter Cable 2.25 HP or Bosch Colt PR20EVS 1.0 HP. In my opinion, these are the highest quality routers I have come across (they are not a sponsor of this website).
Other useful specifications:
The z axis travel and clearance is 4 inches. The overall volumetric dimensions are 37" long, 21" wide and 27" high for the 13"x24" version. Add 12" for the length for the 13"x36" version. Like the other machines on this site, virtually any material can be cut with the appropriate feed rate, depth per pass and end mill used. The speed (velocity) of the machine is: X and Y movement 500 IPM (inches per minute) or 8.3 IPS(inches per second). The machine can go faster, the this is my recommended setting. Like all of my other machines, the code that is used all depend on the software that is used to control the machine. A couple of titles that I recommend are Mach3 (accepts g-code and a couple of other file types) and EMC2 control software for Linux.