Hi
Thanks to MichaelG for the link, just what I needed.
Size I'm aiming for will be 1.75" to centre in horizontal mode, max chuck size will be 3" and the extra 1/4" clearance is in case the chuck jaws are outside the chuck body.
This size will suit my needs as mostly I am working with small items and will even when in vertical mode still leave reasonable distance spindle to job.
Thanks Graeme for your post, the GHT is OK but to use at an angle or in a vertical mode it needs fitting to a tilting table and so then becomes too large for my needs.
Regards, Emgee