A dobby is an alternative to treadles or levers tied-up to select the shafts on the loom. It is programmed by the weaver to raise all of the shafts required for each shot of a repeating pattern. Two options are available for the hand loom weaver; mechanical or computer operated dobbys. In each case the shaft for lifting is selected by the dobby mechanism, and the foot pedal provides the lifting effort.
In a mechanical dobby loom, pegs are set in each of the lags making up the dobby chain. These trigger the shaft operating mechanism as the foot treadle is operated, moving on to the next lag for the next weft shot. With a computer selected dobby the triggers are activated by the computer program on which the weaving pattern has been designed. The weaving program and the dobby plan can be changed with a few clicks of a mouse.