DTIs - 5 vs 1 Tenth?

[MaverickNH]

My 1st DTI was a cheap Chinese unit which has corroded - maybe I’ll keep my next one in a desiccant box.

For purposes of vise locating and workpiece alignment, should I be looking at a DTI with 5 tenths or 1 tenth graduations? If I’m understanding right, the tradeoff is reduced range - 0.008” vs 0.030” for the Mitutoyo 513-473-10E vs 513-472-10E.

I’d imagine “it depends” on what I intend to make, so I might mention an Eccentric Engineering Acute Sharpening System kit on its way to me from Oz.

BRET

 

[WobblyHand]

Trade-off is expense and ease of use. 0.0005" indicator is easier to use. I have both and use the 0.0005" more often, because most of the time, it's good enough for what I'm doing. The 0.0001" DTI comes out if I'm doing something more critical, or I'm getting odd readings from the coarser unit. The better one is much nicer, but it's more expensive, so I'm far more careful with it.

You are probably fine with the 0.0005" one.

 

[Ulma Doctor]

.0005”

 

[woodchucker]

.001 for normal work.
my .0001 only comes out for tooling work. I thought I would use it more. I don't. I can read tenths on a .001 to approximate ...

 

[RJSakowski]

A DTI isn't an absolute measurement instrument. You observe changes in readings as when checking runout, tramming a mill head, or sweeping a vise jaw. With careful observation, you can see a .0001" change with a .0005" DTI. This is more than accurate enough for most operations than one would encounter in a hobby machining environment.

For super-critical operations, the .0001" DTI has some value but it isn't necessary for most day to day work. If the choice was one or the other, I would opt for the .0005" DTI.

 

[MaverickNH]

Thanks for the recommendations, all - 0.005" it is. I'll grab a Noga NF1022 to hold it.

 

[MrWhoopee]

Forty-five years in, I still don't own a tenth indicator. I'm starting to feel inadequate.

 

[Jake M]

Thanks for the recommendations, all - 0.005" it is. I'll grab a Noga NF1022 to hold it.

I'm late, but you're on the right track. A half thousandth indicator will STILL let you extrapolate pretty close to tenths, but the better range is your friend. A tenths indicator, due to it's range being shorter than what one can eyeball, is best used AFTER you've used a "oneths" indicator first. They're quite fiddly. That statement comes from a guy who bought a 50 millionths (half a tenth) indicator, JUST TO DISCOVER THINGS THAT MOST PEOPLE DON'T WANT TO KNOW. Even after that, tenths indicators are fiddly to use, and best saved for when there's a payoff on the accuracy.
Too much resolution can be very entertaining if such things amuse you, but for actual, real useful use, for efficiency, for piece of mind, you want the indicator to match the job.

 

[coolidge]

My .0005 indicators cover 95% of what I need to measure, but like some odd metric tap when you need a .0001 you need it.

 

[WobblyHand]

I'm late, but you're on the right track. A half thousandth indicator will STILL let you extrapolate pretty close to tenths, but the better range is your friend. A tenths indicator, due to it's range being shorter than what one can eyeball, is best used AFTER you've used a "oneths" indicator first. They're quite fiddly. That statement comes from a guy who bought a 50 millionths (half a tenth) indicator, JUST TO DISCOVER THINGS THAT MOST PEOPLE DON'T WANT TO KNOW. Even after that, tenths indicators are fiddly to use, and best saved for when there's a payoff on the accuracy.
Too much resolution can be very entertaining if such things amuse you, but for actual, real useful use, for efficiency, for piece of mind, you want the indicator to match the job.

I totally agree about discovering things that you don't want to know. Using a 0.0001" indicator shows vises distort under screw tension and the jaws lift, even tool makers vises. I didn't want to learn that! I live with it, but truly didn't want to see that. Vises and tools are made of rubber when you have high resolution measurements.