Compu-Dobby® History

There are four primary revisions of AVL's computerized dobbies with quite a few sub-derivations. The four revisions are

• Apple-Dobby: approximately 1981
• Compu-Dobby (now called the Compu-Dobby I): approximately 1983
• Compu-Dobby II: approximately 1997
• Compu-Dobby III: approximately 2000

There are many small differences, but one huge difference. The Compu-Dobby I & II (as well as the mechanical dobby) are positive-type dobbies. The Compu-Dobby III is a 'negative' dobby design. A negative dobby is one where the harness selection is defaulted to lift, whereas in the positive dobby design the harness selection default is not to lift. This sounds like a nebulous discussion for us loom geeks, but this one change enabled Compu-Dobby III-equipped looms to have up to 30% lighter lift! Here's a brief description of each Compu-Dobby

• Compu-Dobby I is one solenoid box with a small Control Unit with six buttons on it.
• Compu-Dobby II has two fairly equal sized boxes, one of which has a Liquid Crystal Display unit.
• Compu-Dobby III is one big box, no secondary boxes.

Compu-Dobby I

The Compu-Dobby started a revolution. It was one of the earliest computerized dobby in existence and became a hallmark for AVL.

Compu-Dobby II

Since its successful launch in Summer of 1997, AVL's new Compu-Dobby has received rave reviews from its users around the world. One feature in particular has stood out as a favorite of the Compu-Dobby's users - the AVL Weaving Cartridge. Weaving Cartridges are small memory units that can be programmed with up to ten peg plans. Once the patterns are in the Cartridge, the Compu-Dobby no longer requires a computer connection, but can, in fact, control the loom directly, allowing the user to disconnect the computer from the Compu-Dobby. The Cartridge is connected to the Compu-Dobby via a standard telephone connector, so you plug it in the same way as you plug in your phone. It's easy to use and given the satisfying "click" that we've all become accustomed to with this style connector, there's never any question as to whether or not the Cartridge is in.

You can use one of two methods to send and save your peg plans to the Cartridge:

• Load Directly at the Compu-Dobby. This is a simple method. Just plug your Cartridge into the Compu-Dobby, connect the Compu-Dobby to the Computer, and follow your software's standard procedure for sending pegplans to the cartridge.
• Use an AVL Cartridge Programming Station. This is a popular method if you have multiple users or if your computer cannot be directly connected to the Compu-Dobby. The Programming Station is a kind of "information copier" that works in tandem with your computer. It allows you to load designs into a cartridge so that you can control your Compu-Dobby independent of a computer. Imagine a college textiles lab with a mix of PCs and Macs running different design software. Peg plans can be designed at any computer and processed into a cartridge at the Programming Station. The cartridge can then be taken down the hall, or across the state for that matter, plugged in at the loom, and voila! -- you're weaving with your Compu-Dobby, nary a computer in sight.

Another new feature, the Compu-Dobby II's LCD display, provides weaving and pattern selection information. The display, located front-and-center on the loom, indicates the name of your peg plan, the current pick's harnesses, and the next shafts to be lifted. It also tells you the number of the lag you're on and whether you're moving forward or reversing through your plan.

The Compu-Dobby II design moved the control buttons from a hand-held controller to the LCD display unit.

Compu-Dobby III - Negative Dobby

The Compu-Dobby III was developed in the late 1990s as an overall loom design improvement and to decrease cost enabling a significant improvement in loom prices. The design is a significant departure from the Mechanical Dobby/Compu-Dobby I & II in that it is a 'negative' dobby design. A negative dobby is one where the harness selection is defaulted to lift, whereas in the positive dobby design the harness selection default is not to lift. This sounds like a nebulous discussion for us loom geeks, but this one change enabled Compu-Dobby III-equipped looms to have up to 30% lighter lift!

The Compu-Dobby III has come in the following variants:

• For the Home Loom with 8 harnesses and for the WDL with 8 & 16 Harnesses
• For the WDL with 24 Harnesses
• For the A-Series, PDL & FDL with 8 & 16 Harnesses
• For the A-Series & TDL with 24 Harnesses
• For the A-Series & AVL40 with 40 Harnesses

PDLs, TDLs and AVL40s equipped from the factory with the Compu-Dobby III were produced in very limited numbers in approximately the 2000-2002 timeframe. Additionally, AVL sold for a limited time upgrade kits for outfitting an older PDL or TDL with the Compu-Dobby III. This upgrade was discontinued and is no longer available for sale.

During late-2005 through mid-2006, four improvements were developed for the Compu-Dobby III and its negative dobby head. The :

• New firmware to improve the Compu-Dobby III's resistance to electrical line spikes. It was found in rare cases that electrical line spikes could catastrophically wipe out the memory of the Compu-Dobby III. The improvement effectively created a wall to block the vast majority of spikes.
• Solenoid mounting tolerances were tightened to ensure better capturing of the dobby cable/wire.
• Dobby wires replaced dobby cables. The dobby cable slack adjustment was found to be very difficult for a novice to master. The dobby wires eliminates the need for slack adjustment.
• Upgraded housings and dobby heads. For looms that can accomodate it, AVL began providing this feature to enable easier (and less expensive) harness additions. For example, some 24" WDL 16H looms were shipped with the 24 harness IDU & Compu-Dobby III populated with 16 harnesses, solenoids, etc.

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