Probe Basic tool setter - small unexpected offset

Hi all,

The problem:
I probed distance from machine Z=0 to the tool setter trip point (G90 G53 G0 Z0, then Z probe, result=4.5xxx). I set Spindle Zero to this value plus the measured length of my master tool (4.000), total 8.5xxx. Then with the master tool still in the spindle, I added a new tool number to the tool table (all zeros, saved & reloaded), loaded this number in the spindle, and did Touch Off Current Tool. I would expect to get the measured length of my master tool in the tool table, but I consistently get 4.038x".

The 0.038x" error is not reflected in the machine Z when I jog down and barely trip the tool setter with the master tool. From Z=0, I get a negative Z value that precisely matches the probed height I used to set the Spindle Zero. My tool setter speeds are set the same as my probe speeds. I cancelled or zeroed offsets and this didn't make a difference. My tool setter is a base-mounted Renishaw MP1s, and it repeats to within a couple of tenths using the Z probing routine. I'm running a PB "stable" install from the github repo on bookworm.

What am I missing? Any ideas what could cause this offset? I was on Discord last night (for the first time) looking for help with this and chatted with a couple of folks (thanks if you were in that group). Someone mentioned that a new release of PB was imminent. From something I read recently I understand the tool setter is changing quite a bit, going away from using G59.3 (IIRC)? If this problem is likely to go away as soon as I upgrade, please let me know.

I got the tool setter working after finding the docs for the new PB version, with the new pictures showing what the tool setter values mean. I also watched videos including a couple by Small Shop Concepts. I followed almost the same setup procedure for setting Spindle Zero as the video, but instead of probing the spindle itself, I used a "master tool" I set up that is a known length (4.000").

My Hurco KM3 has a Kwik-Switch 200 spindle, and the gage line is at a specific diameter of the taper. It isn't a surface you can readily probe, and there aren't any good alternatives because the spindle nut encloses the whole bottom of the spindle. I used a spindle probe turned upside-down on the table (in a KS200-300 adapter) and some trig to measure the spindle taper and figure out where the gage line is vs. machine Z=0. Then I iteratively adjusted my master tool length until it measured dead-on. But the master tool length, it turns out, is irrelevant. The problem I have could be demonstrated with any length tool.

I'm *really* enjoying using the GUI with my new 22" touch-screen monitor. My Hurco hadn't been upgraded for a long time, and I needed a newer PC to run a current OS, which also meant a new Mesa ethernet-based control board. Big thanks to everybody who helped develop PB!

Chris

For starters, the develop version is about to become the current stable version, meaning your next update if installed via apt will require the latest updates in the config folder. So it's in your best interest to make the changes if you haven't yet per the notification on the status page.

Probe speed is required to be the same for setting the z zero height and probing the tool, the trigger distance may be the difference you're seeing.

That said, 0.038" is a big change and sounds like a different issue. I'm not certain I follow your description of the spinle nose, and am not familiar with the type you labeled, but my guess is that somehow in your calculation something is off. Maybe some pictures? More clearly show the setup?

It turned out there *was* a G52/G92 offset, with a Z value of -4.038x when I looked at it. And at that point touching off with my 4" master tool in the spindle resulted in a tool length of 8.038x. I edited my vars file and manually zeroed out the G52 offset, and then things started behaving. Offsets are new to me and I wasn't familiar with those or how they are stored in the file.

So, my tool setter now appears to work, repeating to +/-0.0001 or so. Time to break everything by upgrading... 

Thanks for your help andypugh and Lcvette!

Glad you were able to get it resolved!