Hi Michael,
RE: my dead channel.. I have swapped the motors about and they all seem to work fine but I don't know enough to start poking Testmeter cables into the Motor outputs on the board.. I was kinda hoping that it was a software glitch or that I hadn't turned a switch on.. (Fate has a habit of doing this to me when I dive in to some new project.)
I see your company does Solid Surface.. I have been involved in that for many years (mainly Kitchen Worktops and showers) but was involved in casting for a while. Scott Bader stuff.
I hope I do not come across as ungrateful because I am most grateful. I do pass on the favour by teaching Guitar Building for free,so what goes around, comes around.

Neale, wow.. thanks.. that must have taken a while..
Taking your first revelation of your own Low cost build... fantastic.. Exactly what most of us newbies are doing.. It seems almost mandatory to do 2.. and I am perfectly prepared to do that.
I too tried using regular Threaded Rod and quickly realised it was the backlash lag that was the killer.. I accidentally tripped over the '2 nuts with a spring washer between them' trick but I had decided I liked the OpenBuild OX timing belt option rather than Threaded Rod so that's the route I shall be taking.
At the moment I have built the frame with a gantry and all seems OK. It moves easily with no 'slop' but have not yet mounted the motors.. They are still on the bench in the house and will not be moving them out to join the Frame in the workshop until I am happy I have it set up correctly.
Your description of the Cad and CAM is (will be..) very very helpful but I am not there yet.. Possibly by a long chalk if I can't get my motors running correctly. You say you bought good Drivers and Motors...
May I ask what they were and what size your original table was.. (Are you currently doing a Build Log?)
People seem quite reluctant to give these details.. Is it because you don't want to appear to be recommending them in case it all goes wrong? I could understand that.. 'You told me to buy these...'
If I go to Zapp or CNC4you to buy my components then I assume I will get the support and design help that I don't get from China Direct..
Very tempting.
Thanks again.