Dobby Shedding | Dobby Shedding Mechanism

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Experiment name: Study on Dobby shedding mechanism.

Objectives:

1. To know about the different parts formed this shedding.

2. To learn the mechanism of dobby shedding.

Introduction:

Dobby is a shedding mechanism placed on the top of the loom in order to produce figured patterns by using large number of healds than the capacity of a tappet. Dobby is also known as a “witch or “wizard”.

Scope of a dobby:

The scope of dobby is limited between a tappet and a jacquard. The number of shafts that can be actuated by a dobby varies between 6 and 40. Theoretically dobby can control 48 shafts (maximum). However, practically it can control 36 shafts in case of wool and allied fibres. Again, for cotton and allied fibers, it can control maximum 24 heald shafts. In these case healds are operated by jacks and levers.


Main parts:

1.Bottom shaft 

2.L-lever  
3.Upright shaft  
4.T-lever 
5.Upper draw knife 
6.Lower draw knife 
7.Upper hook
8.Lower hook
9.S-lever
10.Bulk lever
11.Thumb lever
12.Jack lever
13.Healdshaft
14.Returning spring
15.Motor
16.Crank shaft
17.Pattern cylinder
18.Pattern chain
 
Dobby shedding mechanism:
Here a climax dobby is described to explain the dobby shedding mechanism. Climax dobby is a double lift double jack-lever negative dobby. Here two jack levers are operated by a single bulk lever. They are joined with the bulk lever by a timber lever and a link. The double lever is fulcrum med at a point and is connected with S-lever.


The S-lever controls two hooks, one upper hook and one lower hook. The hooks are controlled by feelers. One hook is controlled by hooked feeler and other by a connecting needle. The two hooks control two knives that are joined with a T-lever.


The T-lever is fulcrum med and is controlled by an upright shaft and an L-lever. They get motion from motor and machine pulley. When the feeler comes in contact with a peg and when it is not in the contact it goes down.

Conclusion:

Dobby loom is important for its use. We can use 8-12 heald frame in tappet loom but if we want to use more heald frame for more decorative design then we should use dobby loom. This practical helps me to know about the dobby loom and its mechanism. I think this will help me in my future life. 
  
 

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