Changing Z axis 0 height with Cura 14 on the M90

Hi All,
I'd like to use a seperate sheet of glass to print ABS from the one I use for PLA.
The glass I got from a customer of mine is thicker than the original stuff by about .3mm
U use Pronterface/Slicer a bit but more and more these days I'm using Cura V14.
Is there any way to offset the Z0 height in the software? (both)
I could recompile the FW but it seems like quite a faff just to swap between materials.
I was sure I'd seen a setting somewhere in Cura to set up a Z offset but i'm damned if I can find it now?
Anyone any ideas or am I stuck modding the FW each time?
Cheers
D

I think the easiest way is to add some g-code at the start of the print. Assuming your bed is levelled for the thinner sheet it would be something like this for a print on a 0.3 mm thicker sheet:

G28 ; home all axis
G1 Z0.3 ; move to 0.3 mm above Z=0
G92 Z0 ; set the current position to Z=0

More on G92 here: [reprap.org]

//edit
A bit safer option, without the chance of crashing into the bull clips could be:

G28 ; home all axis
G1 Z10.3 ; move to 10.3 mm above Z=0
G92 Z10 ; set the current position to Z=10

Edited 1 time(s). Last edit at 03/22/2014 06:05PM by Banjer.

Thank you for that Banjer, I'll give that a go. Definitely a better solution than changing the FW each time!
Cheers
D

You can use the "Machine" option within Cura to define a new Machine for the Mendel90 with thin glass and thick glass. Then create custom start G-code for each that accounts for the glass thickness. This way by simply selecting the "Machine" you can slice and print with the least amount of effort.

Fl0yd