Problems with stepper speed

I'm configuring a Pico-Systems Universal Step Controller with Xylotex 4 axis driver to control a Wabeco D6000E lathe. My goal is to make the best worm and wheel I can, starting simply, and increasing sophistication as needed.

Worm
This requires spindle/z axis sync - first I'll try a simple single pulse per rev spindle encoder without spindle speed control, then I can add the Pico-Systems spindle DAC and a higher resolution spindle encoder and/or z axis encoder.

Wheel
This requires a rotary table to be mounted to the toolpost and a synchronised hob to be driven by the spindle. I've got various high resolution rotary encoders I can use for the rotary table.

I'm running LinuxCNC 2.5.3 on the recommended release of Ubuntu and having a few issues:

1. My PCI parallel port is at address 0xe400 - I've added a parameter to the univstep_load.hal 'loadrt hal_ppmc port_addr=0xe400', but it doesn't find the port unless I open a terminal window first, and type '$ sudo modprobe parport_pc io=0xe400' followed by '$ sudo modprobe lp' - I'd welcome any ideas as to how I address this in the .hal files

2. My stepper speeds are very low - they are 1.8 deg, running 1/8 microsteps with a 2.5:1 belt reduction and 4 mm per turn lead - I make this 1000 micro steps per mm. Increasing max speed, acceleration and pid velocity doesn't seem to have any effect - SOLVED: - rather embarrassingly, this was being limited by my value for MAX_FEED_OVERIDE!

3. After jogging an axis a set distance, the stepper takes a time to settle - reducing the default PID 'I' value from 100 to 10 has helped, but not completely eliminated the problem. This is particularly affected by jog speed - so if I jog 0.1 mm at 50 mm/min, there are no 'settling' steps after the move. If I jog 0.1 mm at 5 mm/min, I can hear a succession of 'settling' steps after the move - the gap between them gradually getting longer until the steps stop - there is no physical encoder involved, just the stepper and the USC's virtual encoder position being sent back to LinuxCNC.

4. The example Pico-systems .hal file has 3 axes defined for thread sync - I'm currently using x & z, but not sure whether I need to somehow suppress the third one for the moment (not sure what it is either).

Any help with the above would be much appreciated

Richard

Thanks Andy - I'll try both of the steps you have suggested.