What is the difference of a bowden and direct drive system?

The extruder is a important part of the 3D Printer and consists of a filament driver part (Cold End), where filament is pushed by a motor and a part that heats up the filament (the Hot End). The difference between the Bowden and Direct Drive solution is that in a Bowden system, the filament is transported through a tube, generally in a bow, between Cold End and Hot End. In a direct drive system there is almost no distance between the two. The term Direct Drive is ambiguous, as it may also mean that there is no gear transmission between motor shaft and filament.

Some advantages of Bowden over Direct Drive include:

• The mass of the motor is generally attached to the frame, so it doesn't have to be moved. This increases maximum print speed and backlash effects in your 3D print;
• It is easier to make a multi-head system, as the bulky Cold End parts are positioned onto the frame.

Of course there are also disadvantages:

• As with the length of the tube, it takes more filament to build up pressure onto the nozzle output. This requires increasing retraction to compensate, to avoid stringing;
• Because of the previous point it is generally also much harder to use flexible filaments at decent speeds;
• Tubing adds another point of failure in driving the filament, mainly poor tube couplers will give out under higher pressures during fast printing.