Centroid Zref, part and tool length offsets - notes to self

Tool length offsets and work coordinate setting:
Got my knickers in a twist trying to recall how to set up tools and parts. It's not rocket science but that's no consolation.

Here's cnckeith explaining Zref and tool length offsets.

It's a bit confusing to be mixing a Renishaw probe in with this business. I have both a TT-type tool setter and a Renishaw probe. For tool length offsets, it expects to use the TT device. For work offsets, it defaults to the probe. 

Part offsets:
The important bit is choosing "Auto" for work (WCS) position setting, not "Probe". With the latter, the probe will withdraw by a configured amount (1mm on my system currently), so if you choose to manually zero the relevant axis at this point, you'll end up with an offset. If you use "Auto" for part position setting, not only will it not introduce and offset but it will also zero the axis for you.

Zref and tool length offsets:
The idea is to avoid having to remeasure all the offsets each time you move the table / knee vertically. Keith explains that fairly well. It's fairly simple - each time you move the knee, you fit the Ref tool (T1 in my case) and run the "Zref" "Auto" procedure. This will acquire the G53 machine z coordinate.

Switching between displaying machine coordinates and work coordinates:
Type "Alt-D" to switch. Simple enough but vuried away in the manual....