Angular feed rate?

Hi,

I am using LinuxCNC to run a filament winding machine that I have built. The machine has a carriage that is actuated by stepper motors on the X and Y axis to control the position of the yarn guide and hence the way that the yarn is laid down on the mandrel. The mandrel is controlled by a stepper motor on the A axis and draws yarn onto itself through the guides on the carriage... very typical of this sort of machine.

I want to be able to programatically set the rate of rotation of the A-axis and then have Linux CNC drive X and Y feeds off of that. This is important because I need to be able to control the rate at which yarn is drawn onto the mandrel.

It seems that the way the F codes work feed is always controlled by the XYZ (linear) movement, if that type of movement exists, and ABC (rotory) movement is driven to sync with the linear movement. I want just the opposite... basically XY feeds would be synced to match up with a set revs/min on A.

Currently the best solution I have found is to manipulate the maximum revs/min setting for the A axis in Stepconf. This is getting me by, but I would very much like to have better control so that I can make my process more time efficient (There are things that are taking 10 mintues because of max speed limiting, that could be accomplished in 1 min!!!). Basically what I want is to have the mandrel run faster during some operations and slower for others.

In some sense, I really am looking to control the "surface feet" on the mandrel. This sounds like a basic spindle function, but I also need to have quite precise control of mandrel/spindle angle in order to create various features of the (pretty intricate) wind pattern.

It seems like this might be possible, but I am unable to find guidance to a solution in the manuals so far.

Any suggestions?

Thanks,

Bill