As known from various blogs the original heatbed is not flat. A glass plate (e.g. IKEA 600.740.07) can be mounted with brackets on the printing bed. Then the z-reference must be readjusted.

When printing with ABS warping can be avoided by coating the glass plate with UHU solved in acetone. In this case bed temperature is 90°C and filament temperature 210°C. For large ABS-parts glue a piece of paper on the mirror with a glue stic and coat paper surface with ABS-juice, the parts will stic 'like hell'.

In order to achieve the temperatures required for ABS-printing a separate power supply is required. Here, the S-150-24 from Mean Well is proven, the output voltage can be increased by a small potentiometer up to 28V and thus the heating time can be shortened. A piece of felt (4-8 mm) between the heatbed and the aluminum plate will reduce heat loss.

A driver board is required between the power supply and the controller board of the K8200, which also enables the timing for cooling the extruder heatsink. 

circuit diagram and EAGLE-files in download section