Printing not satisfactory.  Motion in X and Y is extremely slow and extruder motor is skipping.  The Z height is about 0.2mm too low (easily altered).  Actually, homing is a bit slow in the Y axis, slower than the X axis but nothing like as slow as when printing.  Cancelling printing leaves the hotend and bed heaters on - they have to be turned off individually by clicking on the appropriate heater.

Adjusted Z trigger height from 2.5 to 2.7mm and it's correct now.  Still printing extremely slowly, of course.  Think I'll try another item to print.

Tried a simple 100mm square by 30mm high block.  Estimated printing time from Repetier Host was around 4 hours.  Estimated time left on the Duet read 40 hours - ten times as long!!  The extruder motor is skipping a lot but extruding filament, though I think too much.  Looks like the X and Y axes are only running at one tenth the speed set (46mm/s) but it's trying to extrude as if it were running 10x faster.  This is using CuraEngine within Repetier Host to generate the G-code file which I then transferred to the Duet.  I'll try reducing the print speed in CuraEngine and see what happens.

Halved the speed and it's better but now the print head seems too close to the bed so I'll adjust it to a higher value.

Not sure this is working...  Adjusting Z height that is.  I don't think this command line does what I think

G31 P500 X24 Y0 Z3.0              ; Set Z probe trigger value, offset and trigger height

I thought the Z parameter set the Z offset but now I don't think it does.  The problem is the different terminology used by the Duet authors compared with marlin.

G31 sets the probe offsets. Does your probe trigger at 3mm above the bed?

You can dynamically alter the z height using the babystepping controls on the Print Status page.

Actually, it does by the opposite from what I thought.  Set to 1.5 and much better   I'm going for a different item with a shorter printing time.

Something very strange going on here!!   Designed a test model in SketchUp - 100mm square 3mm thick and 20mm high as shown in the screenshot (1st pic) the photo shows the result of printing part of the first layer.  Some distortion due to camera angle but doesn't explain printing a 3mm wide side as around 15mm!!

Tried a square now trying a circle/ring - Test Ring 100mm OD 2mm thick 10mm high

With this print the machine is running incredibly slow again and the extruder is skipping.  There is something very strange going on.  The Duet has been set to be Marlin compatible so slicers that produce standard Marlin compatible G-code should work fine with the Duet.  I guess I must be doing something wrong but what!?

Here a photo of the print as far as I went.  This was 16 minutes printing time. 

What does the preview look like in the slicer program. If possible use a stand-alone slicer to see this.

I can use Cura as a strand alone slicer.

Hmm... can't find Cura - maybe it was on my Win 7 desktop that died.  I'll see if I can download it.

Downloaded Cura but it won't open *.gcode files.  Or do you mean the *.stl file?

This is the STL file in Repetier Host.

It needed opening from within Cura rather than choosing Cura as application to use to open the file.  Here is the ring gcode file in Cura.  Seems to have acquired a very wide brim.

Re-sliced it with CuraEngine making sure Adhesion Type was set to None.  This is the result of opening the .gcode file in Cura.

Printing is still incredibly slow but it doesn't seem to be producing a wide brim now.  Extruder motor still skipping.

It's weired, I've reduced the speed from 23mm/s to 16mm/s and it's printing a bit faster.  Also increased the extruder motor current to 1.4A but it's still skipping though not as much.

Here's the print - stopped after 13m.

Taking printing speed right down to 10mm/s and trying again.  Not that this can be the problem - I mean how can reducing the printing speed set in the slicer increase the printing speed - it nuts!!  Something is wrong somewhere.

Here's the print after 7m.

Reduced printing speed to 4mm/s for the first layer and the speed is only slightly faster 5.5m instead of 7m to get to the same place.  The print is pretty much the same.  Far too much extrusion but that might be calibration though that was from calculation which has proved alright in the past.

Found out why the Y homing was slow - the acceleration was set to 20 whereas the X was set to 500.  They should be the same for CoreXY so I've increased the Y to 500 too.  I guess the low Y value was for Y moving beds.  Let's see what happens now...