Z-axis compensation level

It's a daft question, but just to be sure, is the point of the z axis compensation to get the sensor to be a certain height above the bed and program the duet as such.
At more like 1.8mm I have a reading of 950 ish, but for a reading of 650 it is at more like 3.2mm above the bed.

Should I be sending g31 z1.8 p950 to get z home to be 1.8mm then?
The instructions were more instruction and less explanation. I did it all fine... But the figures aren't right.

I changed the micro sd card for one I had and connected up the Ethernet and I had both working. I think it should say in the instruction that if you can't get pronterface to interact, then try the Ethernet settings. I gave it a rest for a week as I fancied a break from triumphing over tribulation.

It is a lovely bit of kit though if anyone's worried over negativity.

I have a similarly high Z reading as 1.8mm. I believe the idea was to reach less saturated range for the sensor hence the aim for around the 700 range.

I have gone with g31 z2.9 p692

what it does is tell the head to move until the IR sensor reads 692 at this point it now knows its 2.9mm from the Z0 point and will move down 2.9mm down by itself.

So g31 z3.2 p650 would be right for you. I should add as IR is so sensitive to ambient light at the moment I manually set Z0 for prints.

Dan.

You should calibrate at a height that gives you a reading no greater than 750. I changed the resistor values on the sensor board to make it less sensitive to ambient light and bring the reading down to ~600 at 1mm. So I calibrate at 1mm. Even so, when the sun is shining, I have to draw the blind.

I had plans to change the sensor to modulate the IR and thereby cancel out the ambient light, however RRP are already working on something similar, so I've put my plans on hold.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Cool, makes sense now.

btw bright incandescent artificial light also affects the sensor. My sensor (before I changed the component values) was unusable, until I turned off the 50W halogen ceiling light above the Ormerod. So try taking sensor readings with only fluorescent or LED illumination, they may be lower.

Edited 1 time(s). Last edit at 01/12/2014 03:04PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].