As a guy who also has spent too many years with CNC equipment, and NC before them, I've got more than a few doubts as well. As has been stated, the surface finish(peaks and valleys left from feeding the tool, microscopic tears in the metal, ect.) would have to be better than plate glass to allow such a runout measurement. As has also been pointed out, if the measurement was taken within the length of the chamber, your only checking runout of the cuts taken in the chamber, it could be(maybe not) out a bunch from the bore itself. Not good. The fanuc control in the picture only shows to 4 places. Many measurement tools will show resolution past 4 places, VERY few give accuracy past 4. Check out the factory quoted accuracy of the lathe. Most will show accuracy to be in so many tenths, but "repeatability" won't match that. These types of controls also have parameter adjustable backlash compensation to "compensate for wear or screw inaccuracy. The best bet is to have the lab guys "laser" the thing in. However, the ones I have seen didn't even come close to measuring to the number of decimal places quoted above, let alone acheiving such accuracy. This doesn't even get getting into trying to measure runout in the spindle with it's own runout problems.
Just another disbeleiving CNC programmer and Engineer

Mr Mock,

Seeing as though you have decided to put an end to this discussion I started, let me quote one final thing someone said earlier: "it seems he who doth protest..." or something like that leads me to bleieve one thing. You obviously took for granted what someone, or a group of someones, told you. This also brings up another quote attributed to someone I do not know: "Belive none of what you hear and only half of what you read" Perhaps you should have researched your information. Please let this die; I have the utmost respect for the gentlemen quoted in the article and do not wish to besmirch (SP) their reputations.

Jim

Forgotten who started the whole thing?

Chuck

You gotta excuse us old farts from Minnesota every once in awhile.

Blue

What's that old saw "Horse racing is the sport of kings, Benchrest is the sport of fustrated machinists"

Toolmaker

Jim or Clark
One more quick question. I have decided to try running a boring bar in before the reamer, it seems as though it might make things a little more accurate. Whan you run your reamer in on top of the bored holes, do you have any problems with it grabbing on the ridges left by the boring bar, or does it cut over them with no trouble. I would like to try and reduce my runout to somewhere around an eigth of an inch. Thank you sirs. Bob