The objective of this research was to develop salacca thorns removing machine for exporting salacca. The prototype machine had the dimension of 1.6 x 2 x 0.6 m (WxLxH) and its structure was made of steel. The reciprocating tray was made from aluminum mesh screen and the two brush rollers were made of nylon. The reciprocating tray set and two brush rollers sets used 1 hp, 220V electric motor as power unit, while 0.5 hp, 220V electric motor was used as power unit to tilt the reciprocating tray. All components of the prototype
were controlled automatically by programmable logic controller (PLC) installed in the control box of the machine. The working capacity of salacca thorns removing machine was 900 kg/hr and the power consumption was 1.47 kw. The optimum conditions of working speed were 110 rpm of the reciprocating tray and 14 degree tilt angle of the tray. The prototype machine could perfectly remove the thorn from salacca. The de-thorned salacca could be stored for more than 3 days at room temperature without losing its quality which is the same as removing thorns by human labor. Results of economic analysis showed that the prototype costed 82.92 baht/kg whereas human labour costed 90.61 baht/kg while product quality
was the same.