A bit more progress on establishing the beam path. It has to get from the laser tube to be running parallel and plane with the X axis where it is again deflected (by a mirror on the X axis) to be parallel and plane with the Z axis. The focus lens will be mounted directly on the Z axis whereby the focal point can be adjusted for different thicknesses of work. This is the wooden mock-up including adjustable mirror mounts made from MDF (yuk !). The little HeNe beam is quite square to the table in both planes which I think has resulted from a lot of luck.
Hi Bob, Don't know if this is any help but I recently had a PC failure and had to use another PC which had Win XP SP2 installed and I experienced exactly the same problem as you have described. After much time wasted trying to resolve the problem I installed Win XP SP1 over the top of the existing installation and thereafter no problems at all. It has to be something to do with the way the PC handles its polling routines and the way this is interpreted by XP SP2.
The High Voltage PSU is now complete and it's time to start working out the best beam path from the tube to the Z axis. I have made a frame of the same OD as the CO2 tube to hold a little HeNe which sits in the CO2 tube mounts and is ideal for this job. The mirrors I am using are OK for the 633nm and getting the beam path sorted but will need to be replaced with a type that works at 10600nm.
Just a thought Roman but if the dispensing piston was thread driven (rather than air operated) then this could be operated by a stepper motor controlled by another (possibly the A axis) axis of the machine. This should enable full Mach control of the volume at any point of the work.