Tool length sensor direction change

Hi!

I am using QTPyVCP and would like to use my tool length sensor. My CNC Router is set up in a way that it home the Z-Axis to the maximum upper Point is the maximum travel. This means a few millimeter above my bed is Z=0. This way, my Z will always be positive. As I understand, when using the ToolLength sensor in QtPyVCP it has to be the other way round, is that correct?

When Setting up the toollength tool. I set up my Position 20 Millimeter above my Sensor ( Z=70mm). However when trying to probe it just plunges to Z=0 and then moving in X/Y to the Sensor position (shouldnt it be the other way round?).

Is there a way to make it run with my Axis directions? Or should I switch my Z=0 direction?

You should switch your Z=0 direction.  Machine Z-0 (G53) should be at top of stroke (or furthest from chuck for lathes).

This is standard practice on most machines, and is compatible with the qtpyvcp/probe basic tool setter routines.

You can set your G54 (and other) WCS wherever you'd like, of course.

It is also standard practice for cam software and tool length offset. Definitely need to change to standard practice, so reason to reinvent the wheel on this. With a work offset you will be setting zero wherever you want. But machine motion is always z moving down is negative direction.

Yes, I fully agree with you that Z goes into negative direction when going down. However, as I understood (correct me if I am wrong), the probing tool requires you to have Z= 0 at the highest Z-Gantry Position. However, my current approach is that X=Y=Z=0 is in the lower left corner on the Bed. AS I understood Probe Basic requires that you config your machine that (as I did now) X=Y=Z=0 is in the lower left corner but 220mm (for me) up in the air.

Cheers

Patrick

yes the tool length sensor trigger point is used in conjunction with the G53 Z0.000 machine coordnate system to calculate the tool length offset. This requires Z0.000 be at the top of travel for the z axis.

G54-G59.3 woork coordinate system offsets are used to define the zero point for the work or program. these are set independent of machine coordinates but are offset and stored in relation to the machine coordinate system.

you need to adjust your machine configuration so that Z0 is at the top of travel.

Hello,
Perhaps this will be useful for you:
linuxcnc.org/docs/stable/html/user/user-...chine-configurations

It shows the typical axis layout.
When I started out with CNC machining I also ran a small gantry style machine, and for some reason i had the table as Z0. When I changed to Z0 being the top most position (and also used Z0 as 'home' for the z-axis as in the diagram above) a lot more things made sense.

/Peter

Okay, that makes sense! Thank you all!

no worries, hope you get it sorted out!