Hi all, Many thanks for the nice comments.
The way cover is made from a sheet of rubber tread material (off cut from the well deck on my boat) and is fixed at the top by a T shaped bracket made from 3mm alloy plate. This plate is fixed using the existing bolt which acts as a stop for the Z axis upward travel. The bottom end is fixed using the existing rear saddle wiper cover. So no new drillings required to fit and it allows the Y axis to travel back as far as the vice allows. I'm happy with the amount of travel as I'm just in the process of fitting a 3 axis DRO and would have needed to limit rearward travel to stop the scale on the back of the table getting squashed.
I will use a wider piece of material to shield the Z axis scale allowing the reader head to mount on the knee and thus leaving clearance for the oil port. Most people seem to turn the scale with the head to the rear and use convoluted bracketry to move the head, or mount the scale on the knee, all to ensure that swarf does not enter the scale (i.e. have the gap facing to the rear). I think preventing swarf getting anywhere near the scale is a better option. I've experimented with fly cutters, face mills, drills and mills on steel, alloy, brass and cast and I'm certain I can stop unwanted bits getting where they are not wanted.
Clive, If you meant the table cover (which I'm sure you did ) I too have found that limitation. My plan is to build two piece covers which slide into each other a bit like the original covers between the saddle and the knee.Then I can shift the vice around a bit and keep the table T slots free from too much gunk. Probably over engineered but I'm still like a kid with a new toy at the moment.