Here is my video covering making pulleys and/or gears using 4th axis.
G-code for this is very simple. You don;t need to mess with the ratios beyond setting up he number of steps per degree in MACH. From that point on, typically you would simply command the A axis to a certain azimuth with "G1 A30" for example
http://www.youtube.com/watch?v=ViN4t4YI_T4
I use a 'universal' pulley cutting program that you simply input the number of teeth and width of the pully and it calculates everything and cuts the part.
Hope this helps.
--- In DynoMotion@yahoogroups.com, "John" <john@...> wrote:
>
> Reading the blurb on rigid tapping and my take on it is that the spindle encoder reads the input and then keeps the Z axis in time with it ?
>
> Sooooooooooo.
>
> Can the spindle encoder work with the A axis to keep both in time ?
>
> The reason I ask is that if you had a gear hob on the spindle and it read the encoder say 1024, so every 1024 pulses it turned the A axis motor 1 turn.
>
> If the A axis is geared 40 :1 which is a common gearing then the hob would cut a 40 tooth gear.
>
> Choice of teeth is just a simple division calculation.
>
> Comments, flames, low flying bricks ??
>
> John S.
>