Parametric Chain Link Drive Pulley

I had a desire to make some small chain drives for some of my [models](http://www.techmonkeybusiness.com/art-project-articles.html), but wanted to use some classic chain link style chair rather than proper chain drive chain. I had a look on thingiverse and discovered that nobody else had made a model for this. So, after scratching around with a pencil to work out what parameters I needed, I jumped on OpenSCAD and came up with two parametric models. This one has a neck, holes and nut slots for screwing it onto a shaft while the [other](https://www.thingiverse.com/thing:2757710) is just a disk with the chain recesses which can be more easily adapted to other pulley body designs.

The chain size and number of link pairs determines the size of the pulley. So the important variables to fiddle with are;

**Llength**: This is the outside length dimension of a single link
**Lwidth**: This is the outside width dimension of a single link
**Lthickness**: This is the diameter of the li