Touch plate or 3d probe

[Shotgun]

I've got one more input on my Mesa 7i96s board, and I want to add a probe. There appears to be two options, a touch off plate or a 3d probe.
The touch off plate seems to just be for setting tool height or zeroing the Z axis.
The probe seems like it would be able to do that, and set the X and Y zeroes.
Would anyone ever need both? I watched a video of a guy setting up his tool table in LinuxCNC. He used his 3d probe on a touch off plate to set the reference Z, and then set the offset for each tool on the plate.
It seems to me that I could bolt any piece of ground steel to the mill table or use the table itself, probe to set the zero reference height, then use that to set the tool offsets. For most tools, that would mean moving the tool very close, loosen it in the holder and let it slip into contact with the plate, then tighten in place. In that way, all I would ever need would be the 3d probe, and I would only have one repeatability error stacking up.

 

[Boswell]

I have a probe but not a touch plate. I set Z with a separate z-setter. Maybe it is similar to a touch plate but with a spring loaded surface so any overtravel does not do any damage. I set z every time I mount a tool and do not use tool tables. Might someday but as it only takes a few seconds to set Z each time, I don't have to "trust" the tool table. For drill bits, I do exactly like you suggest. I lower the drill bit close to the z-Zero reference level then loosen the chuck to allow the bit to slip down into contact with the surface, then tighten.

 

[Bone Head]

First off, I am not at all familiar with the specific software, probes and machine you're using.
But this as described sounds a lot like a coordinate measuring tool. If what you have is not proprietary, you may want to look at Renishaw tools. CMM operators do some amazing things with them.
And if my suggestion is off in outer space, just point at me and laugh.

 

[Shotgun]

That's the sort of tool I'm looking for, @Bone Head , but at $750 for a touch probe. . . ouch!
The one's on Amazon are more like $70. Granted, they are very unlikely to last as long. . . but, who are we kidding here. I'm not going to last that long.

 

[DavidR8]

Holy smokes! $750 for a touch plate????
It's just a piece of aluminum with a cable and a plug.
This is the one I have:

Touch Plate | Sienci Labs

Our touch plate is designed for simple touching off in 3 directions without guessing or eyeballing distances. Simply insert the plug into the plate, hit a button, and let the machine touch the plate and find it's position. This is handy for: precisely setting the initial position of a piece of...

sienci.com

Its design let me do Z, X and Y axis.
I also have a 3D probe that I use much less.

 

[Bone Head]

That touch plate is a new one on me.
Our CMMs where I've worked in the past used a 1.00000" ball (?) on a stem screwed into the bed. It also was useful for calibrating the off-set of the ball diameter although that function was actually a part of the software.
For what it'll be used for that $70 Amazon item will probably work. Please post the results you get with it.

 

[Shotgun]

Holy smokes! $750 for a touch plate????
It's just a piece of aluminum with a cable and a plug.

It was a probe. Not a plate. You're reaction is still appropriate.

This is the one I have:

Touch Plate | Sienci Labs

Our touch plate is designed for simple touching off in 3 directions without guessing or eyeballing distances. Simply insert the plug into the plate, hit a button, and let the machine touch the plate and find it's position. This is handy for: precisely setting the initial position of a piece of...

sienci.com

Its design let me do Z, X and Y axis.
I also have a 3D probe that I use much less.

I LOVE that design. It can't get any simpler than that. The only issue is electrical isolation. It seems that it would work great on wood, but would be problematic on a Bridgeport. Either the probe or the plate would have to be insulated. I'm going to have to think on this one for a minute.

In the meantime, I'll probably go ahead and get a $70 probe (it's only $70, and right now I've got nothin' 'cept feeler gauges)