Fed up with poor quality I decided to fix all the annoying bits that kept dropping off and then work out the ideal settings (Also to move the whole lot back into the garage to keep the family happy.
The main fixes were to secure the extruder to the machine much more securely. To get the maximum travel on the z axis. To get the feed so that it was consistent using the small screw eyes from B and Q and to tidy up all the wiring. This worked well.
I also changed the acceleration settings on the stepper so that they were on the maximum (increased from 30 mm/s/s to about 600mm/s/s) This has made a massive difference to the quality although I would like more)
I then checked the temperature that the plastic was being extruded at as it comes out of the nozzle and adjusted this to 235 degrees as this seems to be the preferred temperature for ABS.
I then made a series of Nophead's hearts using from left to right 0.7, 0.6 0.55 0.5 and 0.45 settings on the carve layer thickness. The best by far is 0.5 so my settings now are 800 mm/s, 235 degrees0.6 welding tip nozzle .