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Anyone using the Starrett two or three point digital bore gauges?

I've got all of them from the smallest up to 12". I've never had an issue with them. They all measure on 2 points, the "3-point" versions are only 3-point to help self-centering.
 
And if you are, what is the verdict? Accurate or not, repeating or not?

Thanks in advance.

I don't have their bore gauges but I have a new No.258 Digi-Check Height Master with digital readout. I was seeing the digital readout was ±.0002 from the actual dial when calibrating. Called in and they told us ±.0002 on the digital readout is their tolerance. It repeats without a problem, just have to use the dial for actual numbers.
 
I've got all of them from the smallest up to 12". I've never had an issue with them. They all measure on 2 points, the "3-point" versions are only 3-point to help self-centering.

What tolerances are you operating against? At my shop we have sleeves with +0 / -.0002" tolerance.
 
Don't feel bad, I missed the "digital" part of the question until this re-read. :ack2: Mine are actually all analog dials.

A bore gauge is a tool that I would never want a digital indicator on anyway. In fact I just hate digital indicators.

I am not a luddite who hates digital measuring tools - most of my measuring equipment is digital - but digital indicators just suck. For just about every possible use of an indicator, a needle and dial is easier to work with.

Anyway, I think there is some confusion here.

AFAICT, Starrett don't make a bore gauge with a digital indicator.

They do however call their pistol grip bore mics "ELECTRONIC PISTOL GRIP BORE GAGES", which is confusing, as those things use the mechanism of a three point bore mic, not a bore gauge.

I suspect OP is talking about those, and not a bore gauge at all.

As for using those for measuring +0/-.0002" tolerance, that's pretty much a hard no without a lot of qualifying statements. As a zero comparator using a qualified standard, maybe.

How are you measuring those tolerances currently?
 
A bore gauge is a tool that I would never want a digital indicator on anyway. In fact I just hate digital indicators.

I am not a luddite who hates digital measuring tools - most of my measuring equipment is digital - but digital indicators just suck. For just about every possible use of an indicator, a needle and dial is easier to work with.

Anyway, I think there is some confusion here.

AFAICT, Starrett don't make a bore gauge with a digital indicator.

They do however call their pistol grip bore mics "ELECTRONIC PISTOL GRIP BORE GAGES", which is confusing, as those things use the mechanism of a three point bore mic, not a bore gauge.

I suspect OP is talking about those, and not a bore gauge at all.

As for using those for measuring +0/-.0002" tolerance, that's pretty much a hard no without a lot of qualifying statements. As a zero comparator using a qualified standard, maybe.

How are you measuring those tolerances currently?

I fully agree on dial indicators being better than digital for most tasks. Regarding the gage vs. gauge - Starrett calls them bore gages, not gauges.

Dial Bore Gages
Some manufacturers spell it one way, some the other. Semantics AFAIC. I tend to think of gauges as dials in an auto dashboard or pressure gauge, etc. I like using the variant gages for dimensional measurement. YMMV, all good by me.
 
A bore gauge is a tool that I would never want a digital indicator on anyway. In fact I just hate digital indicators.

I am not a luddite who hates digital measuring tools - most of my measuring equipment is digital - but digital indicators just suck. For just about every possible use of an indicator, a needle and dial is easier to work with.

Anyway, I think there is some confusion here.

AFAICT, Starrett don't make a bore gauge with a digital indicator.

They do however call their pistol grip bore mics "ELECTRONIC PISTOL GRIP BORE GAGES", which is confusing, as those things use the mechanism of a three point bore mic, not a bore gauge.

I suspect OP is talking about those, and not a bore gauge at all.

As for using those for measuring +0/-.0002" tolerance, that's pretty much a hard no without a lot of qualifying statements. As a zero comparator using a qualified standard, maybe.

How are you measuring those tolerances currently?

STARRETT Digital 3-Point Inside Micrometer, Inside Micrometer Type 3-Point Inside Micrometer - 53VE36'|'770BXTZ-2 - Grainger

Technically the naming of the product is "inside micrometer", my bad. This is an example of a non-pistol grip model.
 
STARRETT Digital 3-Point Inside Micrometer, Inside Micrometer Type 3-Point Inside Micrometer - 53VE36'|'770BXTZ-2 - Grainger

Technically the naming of the product is "inside micrometer", my bad. This is an example of a non-pistol grip model.

OK, with that established, I will point back to my previous question, how are you measuring those tolerances currently?

Not Starrett, but I use three point bore micrometers extensively, I have a large number of them from various manufacturers, analogue and digital.

The Starrett you linked states an accuracy of 4µm (that's pretty much standard for these, regardless of manufacturer). Others, Sylvac for example, state that a little differently. The figure is still 4µm but the property is called "Maximum Error".

In my experience that is about right. IME they will repeat quite reliably within the resolution of the reader - you zero on a ring gauge and it will repeatably read zero at 1µm resolution on that gauge, and it will reliably measure the difference between a ring gauge calibrated at 39.998 and one calibrated at 40.002 for example. But if you zero on a 40mm ring gauge for example, and check again on a 50mm ring gauge, then you might see something in the ballpark of that 4µm error.

The 4µm "Maximum Error" is 50% of the tolerance that you need to measure, so on paper, your measurement would have a low confidence.

The reality is that these are the most accurate way to measure an internal diameter short of air gauging, and environmental conditions can feasibly impact a measurement by an order of magnitude more than the stated accuracy of the measuring instrument. Hence why I ask, how are you measuring those tolerances right now? Are you looking for an upgrade, or are you looking for an absolute?
 
OK, with that established, I will point back to my previous question, how are you measuring those tolerances currently?

Not Starrett, but I use three point bore micrometers extensively, I have a large number of them from various manufacturers, analogue and digital.

The Starrett you linked states an accuracy of 4µm (that's pretty much standard for these, regardless of manufacturer). Others, Sylvac for example, state that a little differently. The figure is still 4µm but the property is called "Maximum Error".

In my experience that is about right. IME they will repeat quite reliably within the resolution of the reader - you zero on a ring gauge and it will repeatably read zero at 1µm resolution on that gauge, and it will reliably measure the difference between a ring gauge calibrated at 39.998 and one calibrated at 40.002 for example. But if you zero on a 40mm ring gauge for example, and check again on a 50mm ring gauge, then you might see something in the ballpark of that 4µm error.

The 4µm "Maximum Error" is 50% of the tolerance that you need to measure, so on paper, your measurement would have a low confidence.

The reality is that these are the most accurate way to measure an internal diameter short of air gauging, and environmental conditions can feasibly impact a measurement by an order of magnitude more than the stated accuracy of the measuring instrument. Hence why I ask, how are you measuring those tolerances right now? Are you looking for an upgrade, or are you looking for an absolute?

I checked my OP. What I asked for was feedback from anyone who is using the digital Starrett "Bore gages" (inside micrometer), and if so how did they perform? That's all. "In the field" use versus Marketing Material.

Being digital means, potentially, the ability to collect inspection measurements electronically/wirelessly as you are taking the measurement, as opposed to humping pen and paper.

So it was a ponder on my part, which, as these things go, is entirely gated by whether the device in question is capable of taking repeatable measurements to begin with, to the accuracy required.
 
So it was a ponder on my part, which, as these things go, is entirely gated by whether the device in question is capable of taking repeatable measurements to begin with, to the accuracy required.

I'm sorry you don't like my answer, but it's valid.

To answer your question more briefly, the device in question is capable of taking repeatable measurements, to the accuracy stated.

Whether or not "the device in question is capable of taking repeatable measurements to begin with, to the accuracy required" is a much less simple question.

Nonetheless, a three point bore micrometer is the best hand held small measuring instrument to measure a bore as accurately as possible. The rest is up to you.

I'm sure the Starrett is fine.
 
Now Gregor, I don't know about you, but at this point I'm starting
to think the OP needs to word his posts more carefully. Your reading is just fine by me... :D

Or maybe it's Starrett we need to chase with the torches and pitchforks. :D Though don't they call them 3-point internal micrometer?
 
Now Gregor, I don't know about you, but at this point I'm starting
to think the OP needs to word his posts more carefully. Your reading is just fine by me... :D

Or maybe it's Starrett we need to chase with the torches and pitchforks. :D Though don't they call them 3-point internal micrometer?

There's probably some colloquialisms going on on my end as well to be fair. They are simply called "bore mics" around here (around here meaning "in my workshop, by me and my employees" :). Internal Micrometer is a tubular or stick mic, and a bore gauge is what you thought it was at the start of the thread. This would be better with pictures :D

It doesn't help that all the manufacturers call them different things.

Sylvac calls them "Bore Gauges", Tesa calls them "Internal Micrometers", Mitutoyo has about three different names for them, although "Internal Micrometer" is among those names...

A quick google of "Bore Mic" indicates that it may be a British thing, as practically all the results for that search term are three point internal micrometers, but all the top hits are UK based metrology suppliers...

So it's probably not fair on OP to criticise his terminology.
 
The reality is that these are the most accurate way to measure an internal diameter short of air gauging, and environmental conditions can feasibly impact a measurement by an order of magnitude more than the stated accuracy of the measuring instrument.
Horses for courses ? Assuming you are talking about the three-prong internal mics, I had several Etalon Ingages (I think) with setting rings, they were beautiful things but on an ID grinder I found that the analog indicator-type gages were faster, easier to use, and more accurate. In fact, I disliked them even for regular work, they just never felt right.

The smaller ones worked better than the big ones (for me), if that makes any difference.
 








 
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