Z Axis is always a minus value, right?

[robb]

G3 with v4 installed.

With Z axis at zero the offset in F4 shows a correct minus value. However, on screen in F3/Jog/Pulse I am not seeing the (usual) minus value. The value shown is correct, in line with the F4 screen offset value but, it is shown as a positive number. I understand that Z axis can never have a positive value. It is always below zero and, therefore, minus.

My question is, has anyone else seen this change in the Z value in F3? Mine used to show a minus before the Z-axis value, now I'm not seeing minus and assume (to play safe) that what I am seeing is a positive/plus value. That can't be right? Can it?

I might be missing something very obvious (my usual mode).

I have rebooted the G3; no change.

Robb

 

[evermech]

@robb

the answer is yes and no

yes the z axis works in a minus direction from its home (zero) position, or at least that's how it should work, but

when you set the work offsets you in effect move the ( zero ) position, in z's case, usual to the top of the part. Now when you ask for a negative value in Z axis your tool should move down below the part top (zero) and when you ask for a positive value it should rise up above the top of part (zero)

you should see positive z values in your g code files because of this.

Looking at the big picture though in reality your z axis is always in a negative position relevant to its home (zero) position but the controller calculates the differences in the machine home, and work offset, to display in a more understandable way, the position of the axis. Imagine if we had to do those calculations to figure out where the work is on the table compared to the axis home positions, then figure the different tool lengths etc. It would be a nightmare

anyhow I don't have a Masso screen in front of me but it may be displaying the work,offset values which can have positive z axis values

Guy

 

[cncnutz]

Hi Robb,

The value shown on the Z axis will depend on where Z zero is.
Anywhere above the point is +Z and anywhere below is -Z
This is true for both Machine and working coordinates. It all depends on your machine settings.

If you are looking at the Z axis values in the F4 screen.
F2 Machine coordinate - F2 Working coordinate - F4 current Tool Z offset value = F4 current Work offset table Z value.
Note: you will get a slight discrepancy when you calculate this because Masso only displays to 4 decimal points in imperial and 3 places in metric on the F2 screen but internally the calculations are higher resolution.

Is you Z axis not cutting to the right height or crashing?
If you can provide screen prints showing the F2 & F4 screen along with a detailed description of the problem it is causing we can have a look and see if we can figure out what is happening.

Cheers Peter