Issue with warp (offset issue?)

[aborgman]

Software: CNC USB Controller v2.10.1710.2601

I've been using warp on my PCB milling system for quite a while, and everything works well.

I've been using warp on my larger metal CNC system, and it sometimes works - and sometimes tries to drive the bit MUCH deeper than makes any sense. The last instance was GCode with a Z depth of -0.02, and when the first cut started it tried to plunge to Z-0.145... way more than any warp in the (relatively flat) surface could account for.

Here is my procedure:

Assume 3"x3" part

Install probe
Machine/Offset/Zero
Jog machine to part zero (center)
Machine/Offset/Current XY
Machine/Capture & Measure Points/Measure/Measure Grid Z Offset
Jog machine to part lower left corner (X=-1.5, Y=-1.5)
Machine/Capture & Measure Points/Measure/Set Grid (Set Height=0, X=3, Y=1)
Machine/Capture & Measure Points/Measure/Measure Grid Z
Go To - Zero XY button
Change to cutting tool
Manually jog Z until bit touches.
Zero Z axis (using radio button next to Z)
Open GCODE
Program/Advanced/Warp

There appears to be some offset or zeroing step I'm missing here. Somehow it sometimes ends up with an incorrect Z offset, or warps the Gcode in some fashion that greatly exceeds the actual deviation in surface.

Suggestions?

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[PlanetCNC]

Your zero is in the center? I'm not sure if this is the cause but I never tried this.
Here are our tutorials for warp: https://planet-cnc.com/how-to-use-warp-feature/

[aborgman]

Your zero is in the center? I'm not sure if this is the cause but I never tried this.

Sometimes my zero is in the center. Sometimes my zero is the lower left corner. Sometimes (when doing PCB) my zero is the lower right corner. It depends on the GCode and what CAM software generated it.

On my PCB mill (which is zero at lower right) I don't seem to have any problems. On my other system, I've had occasional problems - the most recent time involved a standard zero at the lower left corner as in the tutorials.

Here are our tutorials for warp: https://planet-cnc.com/how-to-use-warp-feature/

Yep - I've read the tutorial. It's just a bit incomplete.

For example -

It never tells you to make sure offsets are cleared.
It doesn't tell you how to zero Z if you aren't using the tool (and a conductive substrate) as the probe.

I'm using a touch probe - not using the contact between the tool and a conductive surface as the probe switch. That means I have to probe, put in the actual cutting tool (which is a different length than the probe), and re-zero the Z axis.

[sniiki]

I'm having the same problem. I don't know how I'm supposed to handle tool change with the warp feature.
1. Clear work offsets (Work position/offset/to zero). This step isn't mentioned in the tutorial and is crucial, or at least I end up crashing always without doing this as surface measurement seems to always use machine coordinates ignoring current Z offset.
2. Jog to part zero and set XY work zero (Work position/Axis to zero/XY). Z work coordinate remains at machine coordinate.
3. Measure surface and apply warp (load points + enable). All is good at this point and Z work coordinate shows sensible reading.
4. Now if I change the tool and probe it's height (Work position/measure height) it all goes to hell no matter how small the tool length difference is. Tried probing the new tool both with warp enabled and disabled. Weird thing is that even the 3D view shows it's crashing through the object so it's not just machine/work coordinate issue.

Tutorials (the new or the old one) aren't really clear and seem to be missing something like @aborgman said.

@PlanetCNC, could you tell a step by step how this tool change should be done with warp?