Here is a "abridged" version of "indexer for dummies"
1) you need a stepper motor (indexer)
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2) and a controller
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3) That along with the Indexer Virtual Tools and other programs will allow you to do things like this
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4)or this
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5) You can also carve, for example, the same flat design you might use on the circumference of a column. Or a simple fluted column like this
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The examples are endless. Start out looking in the virtual show and tell for some really cool stuff some have done. In my opinion the indexer is probably the most creative addon you could make to your shopbot. This rug cutting application is just another example of how somebody was using their noggin and came up with a "cool tool".
In the Shopbot console look under Tools/Indexer (TI) and see some of the operations it comes with. I will look a bit further for more example pics and more explaination or others can add on..