[shred]

Funny. I learned 'Z bottom of stock' in a "real" machine shop. They do it because raw stock is often not all that consistent in thickness when you are doing thousands of parts from multiple bars and you always know where the bottom is going to be every time; not so much for the top. You can also set up off soft jaws without even having the stock there at the machine and if somebody accidentally sets Z to top of stock, you just cut air until you figure it out. Maybe that's "wrong" in some people's books, but they've made many millions of dollars doing it that way...

IMO It's far more important to either be consistent in how you CAM parts, whatever that may be, or extremely attentive to documenting and verifying what you did every time if you ever go back to an old part file.

.

[mactec54]

Funny. I learned 'Z bottom of stock' in a "real" machine shop. They do it because raw stock is often not all that consistent in thickness when you are doing thousands of parts from multiple bars and you always know where the bottom is going to be every time; not so much for the top. You can also set up off soft jaws without even having the stock there at the machine and if somebody accidentally sets Z to top of stock, you just cut air until you figure it out. Maybe that's "wrong" in some people's books, but they've made many millions of dollars doing it that way...

IMO It's far more important to either be consistent in how you CAM parts, whatever that may be, or extremely attentive to documenting and verifying what you did every time if you ever go back to an old part file.

.

The stock is still in the same place no matter how the thickness varies this does not change the way it can be machined from the bottom up or top down it makes not difference, you are obvious not a time served machinist or you would know this