Heaven help me - I've just bought a delta kit :-)

[curious aardvark]

Well it gets weird.
2 days ago when i was trying to get my head around calibration. the G29 command moved the head down and it pushed down at 3 points round the bed.
yesterday and today - it no longer does that. At the moment all g29 does is cause the printhead to move slowly to the centre of the print bed, touch with the probe and then return to the top of the printer. It does that 3 times and then stops.

Pretty sure I'm going to hav to abandon this auto (thought not really) calibration process.
But why has the g29 command changed ?

***

well if I send g28 and then g29 - it works again.
ll three results are within 1/100th of a mm.

So is that it ?
I have no idea.