Creating Datum Points?

[1CMM4ME]

I have a part I am getting ready to write a program for, but as I look over the drawing, they have called out a ( Datum-B-) at 3mm down on the side of the part. Datum-A- is going to be leveled for my -Z-. Whats the best way to place 2 points on this surface, so I can constuct a line for Datum-B-? Because I'm new to the machine, I figured I could cheat and perform a move point close to the 3mm, then go back and change the Z depth in the edit menu to do this.
But I am sure there is a better and easier way. I have attached a picture of what I am trying to accomplish. I know you pro's have a quick solution.
Thanks for the help in advance...............as always.

B&S "one"
PH10
TP20
Demon Version 4.1

[T Miller]

Measure and level datum a and a point for Dat c you should be good to go after that

[Matthew D. Hoedeman]

EDGE POINT! Use a single surface sample hit and tell it 3mm for the depth, then the points will be exactly 3mm down, every time!

[1CMM4ME]

Thank you gentleman. I must say, this site is the best helpful information and the kindest ridicule on the web.

Patrick

[JamesMannes]

Thank you gentleman. I must say, this site is the best helpful information and the kindest ridicule on the web.

Patrick

Almopst makes ya feel like family dunnit?

[Matthew D. Hoedeman]

Shut up James, before you scare him away!

[1CMM4ME]

James: Have you been drinking and playing that darned ole banjo again?

[JamesMannes]

Shut up James, before you scare him away!

James: Have you been drinking and playing that darned ole banjo again?

I love you guys.