Tool offset help

[MidniteMachinist]

Apologies in advance... I know I've asked related questions before... But I'm really struggling to understand.

I use Tormach TSS holders on my mill. They reference against the spindle nose, so I've set all my offsets relative to that. So, say I select Tool A, which has a Z offset of - 3.583, touch the tool to the top of the work, and set the workspace origin to that point (0,0,0 absolute). Then, without moving anything, , I select Tool B, which has an offset of - 3.110. The Z readout turns red, goes to incremental mode, and changes to 3.110.

Here's where I'm lost. The Z axis hasn't moved, so why did the readout change? Further, the Absolute value is still zero. The tip of tool B is 0.473 higher than tool A, so shouldn't the absolute readout reflect that? Or the incremental?

I've spent hours today trying to wrap my head around this, and I'm no less confused. Isn't the point of tool offsets the ability to use one tool, switch to another, and know exactly where that new tool is in the workspace?

[Yuriy]

When you selected tool A, TouchDRO didn't know that there was an offset (the offset it at 0). When you select tool B, it applies the offset of 3.11" as expected.
You need to touch off with the spindle (which has 0) offset. Then tool offsets will make sense.

When I designed this feature, it made sense to me, but a lot of people get confused. I'll be working on this next (wrapping up settings) in the new version, but I'm still not 100% sure how to make this not confusing. in essence there needs to be a way to tell the app that you had tool A and now want tool B.

Regards
Yuriy

[MidniteMachinist]

Ok, I think I understand now. Using the tool library assumes you're already at your origin, BEFORE you select a tool. I think that's where I was getting tripped up. Thanks for the explanation... It finally makes sense to me now.

Though, IMO, being able to set a zero with any tool would be more intuitive. That's how it's done with CNC machines. All it cares about is knowing the height of each tool, relative to a common datum (in my case, the face of the tool holder that registers against the spindle nose).

James over at Clough42 on Youtube has a good video about it... The relevant part starts at about the 23 minute mark.

Thanks for the help, Yuriy.