Thanks to Andy from UK for the generous photos.
This is a Drill/MillExcel tools, model PDM-30. This is very similar to machines from Chester tools, Warco, King Canada.
It is using :
TDS-3i DRO with scales travel - 170mm, 220mm, 520mm
Below is an unedited email from Andy:
Used the DRO today and it has revolutionised my milling machine, so easy to be accurate now!
As promised some details of how I fitted the scales:
My milling machine is a medium size mill/drill from Excel tools, model PDM-30. This is very similar to machines from Chester tools, Warco, King Canada, etc..
Fitting the X scale was easy, and only needed a couple of 5mm spaces to bring the scale in-line with the reader head.
The Y axis was a bit more involved and required a 4mm back plate to attach the scale to the saddle. Also the side of the bed is angled so I had to mill the end of one of the supplied brackets to get the reader head to mount square.
The Z scale was also mounted on a 4mm back plate, spaced 30mm off the quill casting,
and the reader head was mounted to another modified bracket screwed to the turret.
Celebrating the finished job with a cuppa!