3D touch probe confusion

Hello, I picked up awhile back a 3D touch probe and I can't seem to wrap my head around Z zero.
 I have not installed it yet, installation and configuration I have no issues. I currently have a tool setter and touch plate.

 My question I can't see in my head is Z zero, when the touch probe detects a material surface Linuxcnc has no idea where that probe tip is in space so of course it Zero's Z. Now when you change to a bit and the toolsetter routine creates a zero offset for it the offset is to what?

 My thought was to use the tool setter to detect the toollength of the probe but a combination of multiple spring loaded buttons may throw off the actual tool length.

 Thoughts?
Thanks

What I do is put something flat like a 123 block in my vice. I lower the spindle without a tool in it so that it just touches the 123 block. I use TTS tooling so the nose of the spindle is what the tooling is going to seat up against when the tool is installed. With the nose of the spindle on the 123 block I make a note of the ABS Z value. Now I probe the 123 block. Now check the ABS value of the point where the probe tripped. Don't forget to account for the amount that the probe backs off after tripping. Min is .25 inch.

So if the ABS value of the nose on block is -12.000 and the ABS of where the probe was after the probe is -7.750 then account for the .25 backoff and the gives you -8.000 trip point. 12.000 - 8.000 = 4.000 so the probes effective length is 8". Put that value in the tool table as the length for tool 99 (The probe) Then when you touch of on the part it can take the Z position at touch-off and adjust it by the tool length of tool 99 and that value would be the Z would be at if the nose was on the part. Then when the length of the tool is applied Z will be what would put the tip of the tool on the part.

I hope this helps

 My thought was to use the tool setter to detect the toollength of the probe but a combination of multiple spring loaded buttons may throw off the actual tool length.

This should be easy enough to test.  Make a cut at a known height, measure the probe with the toolsetter, and probe the new cut.
 

Johnny is on the right track. The following works well with qtdragon.
Tormach sell a granite surface plate with a hole in it for TTS tooling.
tormach.com/small-granite-surface-plate-...KYzs44ICkj1ujSHUakPj

Then you can insert your tools into TTS tool holders and pre measure them with a digital height gauge
www.ausee.com.au/products/digital-height-gauge-0-200mm-8
and record each tool's height into the linuxcnc tool table.
Measure the probe the same way as tool 99.
Then you just need select tool 99 and probe the top surface of your work piece. Now whenever a tool change is required, QTdragon's manual tool change will pause and let you change tools and resume your job.

Thanks, Interesting idea, I think though this would work with tool holders. I have a simple collet and the tool mount has slight variations each time I load it.

Thanks, I will give this a try. I won't hold my breath though as I believe deflection may play a role to create a non-repeatable deviation. I mostly work with wood and usually complete a job after setup so a slight variation at tool 1 wouldn't likely hurt.

Thanks, I use qtdragon_hd and manual toolchange with a script I found in this forum. The manual tool change works awesome mostly, I am still messing with the script.

Thanks for the suggestions it gave me an idea! It took all replies to formulate it.

 If I create a base for my tool setter that has a riser. The riser can be any size as long as its lower than the trip point of the setter. This will allow me to remove both known points in space to resurface. Then when I re-install it the 2 known points in space are still referenced to each other.

 Then I calculate the offset from the tool setter trip to the riser top. Now that the offset is known I can adjust the tool change script to detect tool 99, change the X/Y location of the touch point and adjust the offset by the riser/setter offset. This should put the tool length offset routines at the same point as the 3D touch probe creating a calculated common known point in space for both.

 Now job start is similar to before. Manual load tool 99 (3D Touch) or tool 98 (6mm pin). If I load tool 98 setup is as its always been before the 3D touch. If I load tool 99 I get the added features of the 3D touch. Job start should pickup a tool change, use the tool setter and operate normally with either tool 99 or 98 start.

 Whooa! On the Amazon website the probe looked so easy! 
 

I don't have a surface plate or height gauge (yet). I do have a lathe with a DRO. I made a ring that the tool holder fits into. I chuck the ring up the lathe, Turn the lathe tool post holder around so I have a flat surface that will go up against the ring. Zero out the DRO. Move the tool post away from the ring. Insert the mill tool in the ring then move the lathe tool so it touches the tip of the tool. The DRO now shows the tool length. I enter that value into the tool table.

Before I had TTS tool holders I used a touch plate that I had made. It was basically a spring-loaded brass button in a Delrin base. I used to put each OP in a separate G-Code file and touch-off with the touch-plate at each tool change. Now I have an M6 remap that automatically measures my variable length tools like drills and odd endmills that I don't have dedicated toolholders for. It uses that length in the tool table for the tools with dedicated holders.