If the terms are used properly, precision is how close your final result repeats it's self. Precision in a drill chuck would mean how exactly your theoretically perfect drill bit repeated it's actual runout, which would be it's geometrical relationship to the drill chuck. Or in a vice, if you clamped the same theoretically perfect block ten thouosand times in a row, how close to the exact same position would the piece be. Accuracy would refer to how close those final results came to the actual result that you dialed in. In a drill chuck, that would be the deviation from a datum of zero runout. In a vise, you might be looking at the deflection and actual plane that the top surface lands in, and it's deviation from a datum plane that's parallel to the plane defined by the X and Y motion.
When you see either of those terms tossed out without supporting numbers, technically speaking, that's marketing wank. The actual numbers are what you want to look at.
Then throw in tolerance. If it's spec'ed at a max deviation, then that's what it is, or at least should be. If it's just spec'ed at a number, you've got to figure that some are better, and some are worse. Two tenths, or two thousandths? Wo knows unless that's called out...
Precision, high precisioin, ultra precision, any way you slice ti, those terms are being used as branding, and/or casual conversational level to indicate "good, better, best" among a product line in a way that both educated and informed and experienced customers, as well as new, unexperienced, not yet well informed customers, who may not even have taken the tools and their uses to a point that warrants education, and all of the folks in the full range between the two can get something they can sink their teeth into for comparison from brand to brand, and within a brand line.
If you're at the point where you need to know the specifications of a tool, then the actual numbers are what's going to matter. Accuracy numbers, precision (or repeatability) numbers, and tolerance numbers. That will be (hopefully.....) the final answer. But those are what matters.
In terms of the Precision Matthews drill chucks, I just looked at a couple, and I see that a high precision one lists a "maximum of 0.001 inch" of runout. A ultra precisioin one listed a "maximum of 0.0078 inch" of runout. That's kind of an umbrella statement that rolls it all into one number. Both numbers are quite good for a drill chuck. (and probably better than your actual drill bits...) But it kinda only tells you the accuracy. The precision would be how close it comes to being exactly the same every time. In the case of that example, to me it wouldn't even mater. Drill chucks are not a "precision instrument", and the maximum runout is really the only number that's going to affect you. I'm not sure how they label their other stuff, but that's the approach I take. Provided i'm not in a high precision industrial environment buying high volumes of very expensive tooling, I just move past the casual description and looking at the numbers that are pertenant to me. If I were in a high precision production industrial envirionment where fifty millionths mattered.... I'd expect different from my suppliers, and I wouldn't be shopping at the same places that I do for stuff I use at home in a hobby environment, or at work in a repair shop envirionment.
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When you see either of those terms tossed out without supporting numbers, technically speaking, that's marketing wank. The actual numbers are what you want to look at.
Then throw in tolerance. If it's spec'ed at a max deviation, then that's what it is, or at least should be. If it's just spec'ed at a number, you've got to figure that some are better, and some are worse. Two tenths, or two thousandths? Wo knows unless that's called out...
Precision, high precisioin, ultra precision, any way you slice ti, those terms are being used as branding, and/or casual conversational level to indicate "good, better, best" among a product line in a way that both educated and informed and experienced customers, as well as new, unexperienced, not yet well informed customers, who may not even have taken the tools and their uses to a point that warrants education, and all of the folks in the full range between the two can get something they can sink their teeth into for comparison from brand to brand, and within a brand line.
If you're at the point where you need to know the specifications of a tool, then the actual numbers are what's going to matter. Accuracy numbers, precision (or repeatability) numbers, and tolerance numbers. That will be (hopefully.....) the final answer. But those are what matters.
In terms of the Precision Matthews drill chucks, I just looked at a couple, and I see that a high precision one lists a "maximum of 0.001 inch" of runout. A ultra precisioin one listed a "maximum of 0.0078 inch" of runout. That's kind of an umbrella statement that rolls it all into one number. Both numbers are quite good for a drill chuck. (and probably better than your actual drill bits...) But it kinda only tells you the accuracy. The precision would be how close it comes to being exactly the same every time. In the case of that example, to me it wouldn't even mater. Drill chucks are not a "precision instrument", and the maximum runout is really the only number that's going to affect you. I'm not sure how they label their other stuff, but that's the approach I take. Provided i'm not in a high precision industrial environment buying high volumes of very expensive tooling, I just move past the casual description and looking at the numbers that are pertenant to me. If I were in a high precision production industrial envirionment where fifty millionths mattered.... I'd expect different from my suppliers, and I wouldn't be shopping at the same places that I do for stuff I use at home in a hobby environment, or at work in a repair shop envirionment.
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