Hi, I recently bought a CNC router with the rotary attached to the frame. I'm learning the machine in steps so I've only used the XYZ axis and all went fine. now that I am more confident to use the 4th axis rotary I can't get it to turn. I've watched a lot of videos and tried to follow suit but it got me nowhere I'm using mach3 the position remains 0.000 when i try to jog on screen.

can anyone render some help to a newbie to this exciting field       

Check the Ports and Pins, Motor Outputs under the Config menu and see if you have 4 axis configured and if yes then is it A,B or C that is ticked.

Once you know this you can go to MDI and type G00 G91 A90, B90 or C90 and the axis should move.

Mr Graham, thanks for your help. I checked the recommended settings and everything seemed fine. I then reinstalled the mach3 programme and redid all the settings. Now I'm getting the 4th to move with the x-axis key. Is it possible to have the 4th operating independently?

Another issue I would like some assistance with is accuracy. the steps were done using the auto function in mach3, I did it for 10mm /1cm however, when I send a file to cut I'm off by 25mm less than my desired size. The manufacturer settings are way off I'm using aspire to generate my G-code. is there anything I am overlooking here.

You need to post some screen shots of your settings, 4th should move independant of any other axis, you may have it slaved to X by mistake.