The mechanical dobby is a program bar with pegs system. The numbered holes in the program bars correspond with harnesses of the loom. If you want a harness to be raised, you place a peg in the corresponding hole of the program bar. Your series of program bars can be as long as you like; however, if the number of program bars becomes very large, you may want to consider an electronic dobby.
The liftplan of your weaving pattern has to be programmed on the dobby program bars. The pictures in the slideshow are showing the Louët Octado. The Megado works the same but the dobby bars are longer. The transport of the dobby bar chain of the Magic Dobby, is controlled by a manual rotation of a square knob.
An overview of the working method of the mechanical Dobby:
- Dobby liftplan: For each pick in the weft pattern repeat, a dobby program bar is provided with pegs
- The chain of programmed bars is as long as the number of picks of the weft pattern repeat
- The pegs on the program bars will push the selection to the dobby hooks
- By pushing the weaving pedal the dobby knife will catch the selected dobby hooks and the weaving shed is opened
- Pushing on the dobby pedal will transport the program bar chain to the next selection.
- You can easy change the weaving direction.
- By repeated pushing on the dobby pedal without weaving you can skip programmed bars.
Considerations of choice for mechanical Dobby
- The complete weaving report (this is the repeating pattern) must be 'pre-programmed ' on the dobby program bars.
- In block patterns with tabby, like summer & winter, many dobby bars are needed.
- If you weave many block patterns, an electronic dobby is recommended.
- Depending on the loom type, a number of dobby bars are included with the mechanical Dobby. Extra dobby bars can be purchased per set of 10 pieces.
- There is a maximum of the number of dobby bars because the chain will hit the ground at a certain moment.
- The preparation of the dobby bar chain consists of applying the pegs for the shaft selection. Especially for Dobby looms with many shafts this is a labor intensive job.
- Advantage of the mechanical dobby is independency of a computer with weaving software. However, to optimally use the possibilities of weaving on more than eight shafts, the use of weaving software is almost indispensable.
- During weaving, an extra action is always needed to transport the dobby bar chain. With the Louët Megado and Louët Octado you do that by trapping the dobby transport pedal, at the Magic Dobby you turn the dobby bar chain by hand.