Need Help!- Z Axis setup

[leaveme]

I built a fixed gantry hybrid (aluminium & MDF) machine.
I haven't installed any limit switches yet and planning to use the soft setup for the time being. One thing I can't configure is Z axis: don't really understand whether I'll configure "0" at top or bottom.

For instance, if I set zero at top then bottom (base plate) will be -6.10.

| (0.00)
|
| (-6.10)
---

Please advice, what you guys are configuring for you case?

[Phife]

that is correct, typically the Z home is at the top of the Z, and as it travels down it goes into the negative.

[leaveme]

Thank you, Phife. It helps me for Z setup.
I also need some help on material setup (since I'm first time with CNC).
For instance, my base plate is at -6.10 and I put the material (i.e height 0.75") there for curving. How do I configure it in Mach3?

Thanks in advance.

[M250cnc]

Originally Posted by leaveme I also need some help on material setup (since I'm first time with CNC). For instance, my base plate is at -6.10 and I put the material (i.e 0.75" dia) there for curving. How do I configure it in Mach3? Thanks in advance.

The norm is that the top of material that you are machining is set at zero then any cut is then a minus number. So to machine 1/4" deep then the cutter is -0.25"

I do not understand the last paragraph i.e. 0.75" dia you need to explain this

Phil

[RomanLini]

Interesting views.

I run the opposite, the Z axis is at 0 when the tool is at the deck, which is set by my Z tool height setter.

Then if I make a cut at Z=2mm it makes the material 2mm thick etc. I can't imagine any Z system better than that, but maybe there's something I missed.

[Phife]

Originally Posted by RomanLini Interesting views. I run the opposite, the Z axis is at 0 when the tool is at the deck, which is set by my Z tool height setter. Then if I make a cut at Z=2mm it makes the material 2mm thick etc. I can't imagine any Z system better than that, but maybe there's something I missed.

That may work for you, but I use a vacuum table and sometimes I use vacuum fixtures of various thicknesses. I find it easier to have my Machine Z 0 at the top of the Z travel, and then I set the Job Zero to the top of the work piece. The program then doesnt care if the part to be machined is on the bed surface or on top of a fixture.

[hemsworthlad]

Originally Posted by RomanLini Interesting views. I run the opposite, the Z axis is at 0 when the tool is at the deck, which is set by my Z tool height setter. Then if I make a cut at Z=2mm it makes the material 2mm thick etc. I can't imagine any Z system better than that, but maybe there's something I missed.

Ye but your in OZ so everything is upside down. . Lol

[pointcloud]

I got a shovel, see I am standing on the ground at sea level... I dig a hole 1M deep, is that I added a meter hole? or I subtracted a meter hole? I dont know go figure?

Safe "Z" covers the tallest trees in the forest? is that 100M 0r is that -100M?

I guess I am saying I want my submarine to go -
and
I want my airplane to go +

I'm just saying?

[leaveme]

Thanks guys, I got some useful info.
Seems it will be bit easy if prepare a probe plate for zero setting. But material top (height) will be zero in this case.
Is my understanding right?

[hemsworthlad]

I would defiantly recommend probing for material height.

I use Machblue screen set with a few mods to the probe scripts to suit my needs and wouldn't be without it, must save me 30mins a day compared to messing with slip gauges etc.
The other probes such as edge finding and hole centering probes are very useful when needed as well.

I always work in the negative and my Z Machine zero coordinate is at the top and homes to this.
I think you'll find this is the more common way people work.

[cyclestart]

Originally Posted by leaveme For instance, my base plate is at -6.10 and I put the material (i.e height 0.75") there for curving. How do I configure it in Mach3?

Use the 'touch-off' feature. Bring the tool to the surface of the part and designate that position relative zero. Really easy if you're only running one tool. Beware of entries in the tool length offset register. I'm not a Mach user but those general rules should apply.

If the finish height on a part is 2" I might measure to the table top and factor in the 2" in the touch-off dialog box. Depends if the unfinished top surface is irregular. (That's assuming the part is clamped directly to the table.)

If you're running multiple tools there are more decisions to be made.

[pointcloud]

yes stock or material should be Z0, and Z-1 will be a cut equalling -1 for measuring system your machine is set to use.