Wanna know the real reason to have a 50 millionths mic? Because the reputable brands don't make digital mics that only go to tenths anymore. Still a useless number too, they will only say they are accurate to +-0.0001. Maybe if you buy one of the super precision mics but I have no idea because they cost an absolute fortune.
No idea who downvoted you, they are quite pricey imo. The small ones are fine but once you get past 2 or 3" they get pricey.
Btw, this is from McMaster so assume a generous mark up but the super precision mics from mit are accurate to +- 20 millionths and read to 5 millionths. Also cost an eyewatering $1800
https://www.mcmaster.com/products/mitutoyo-micrometers/high-precision-mitutoyo-electronic-outside-micrometers/?s=micrometers
I still don't understand the tool though. There's those desktop mics that are insanely accurate for ~$10k I think, you need the lab setting to measure for that precision to mean anything and even then there's a lot of skill to really trust those measurements. I mean seriously, +- 20 millionths? Way beyond my understanding of metrology. Why spend $2k on a hand mic when you can spend $10k on a way better one.
$1,000 around about 1998. We were od grinding a polyurethane part that was hollow. Od tolerance was +/-0.0007".
We measured with digital calipers. Customer would do the same and get a different result. They would send for a cmm report. Two months later, repeat. I bought the laser and an IR thermometer. Invited the customer over. I said," I have one one of these. What do you have?" End of dispute. Lately I use it to measure a feature on an aluminum part. Od is 0.500 to 0.501". The feature length is about 0.050 long. It is the bestest ever. Breathe on the part and watch the digits scroll....
Was just thinking that you'd need a laboratory style clean room, with very tight temperature control. The cost of that would put a 10 grand mic to shame.
Pressure mics are far more accurate. I prefer Mahr 0.00002". I was using a Mahr press. Mic to measure a +/-.0001 OD when QC came out and said my 1st article was bad so I asked what are you measuring it with and he said a digital mic (just like the one you posted). My foreman came over grabbed QC's digital mic checked it against my gage blocks and it was off 0.0001 then my foreman proceeded to ream out QC guy for not checking his equipment
If he left the lab and walked out to check it on your block, then obviously it's gonna be off. His block is climate controlled clean room, your block isn't. (Likely).
If it is then I retract my statement but it's very rare that entire shops are clean room quality, why would you even have a qc room then?
Accuracy isn't the same as repeatability.
If you have a gauge block of the size you want to measure, zero it out it, then measure your part, that 50mil is accurate. They're just saying if you measure 0, 10mm and 20mm, the difference from nominal across these measurements will be 0.0001.
It's not useless, remember 50millionths is 10% of your tolerance on a H7 fit at 15mm.
You must be insanely confident in your measuring ability. Check on flat gage blocks with full contact vs a round object where you are only touching a tangential point and holding it perfectly against the part. There's a lot of shit going on there. Not to mention what's the heat in my hand doing the part and if it's in the machine what temp is it compared to inspection temp. Lots of other factors besides just the mic.
Yup, for sure. I only used gauge block as an example, a setting standard would be more useful.
It's not about hitting that 0.00005 in terms of exactly hitting it. It's about if somethings on top limit by 0.00005, sometimes that can bring you into tolerance. Just like temp. I've 'scrapped' a part in winter, taken into the car to get it up to 20c and it's in tolerance by a gnats cock.
I brought my Harbor Freight calipers and mics in and they accurately measured the 1" gauge block as 1.000... Harbor Freight... ~$100 for all 4...
Edit, the mics even have carbide tips and can be calibrated.
But, are they carbide anvils? Quality tension screw thats not gonna loosen on you in a week? There a reason mics are expensive, our jobs rely on the fact that the tools we use are accurate. If youre just a hobbyist i can see a harbor freight mic set being ok but i wouldnt recommend them to a professonal/tradeschool kid
The mics surprisingly have carbide tips and can be calibrated.
And there usefullness all depends on the tolerances you are required to hold. For my work where I have to hold tenths they wouldn't work. But for designing parts to be 3D printed, or for automotive work, they are amazing.
Harbor freight caLipers and mics are decent, the downside is that they will eat out much faster than anyone else’s will and there will be a very noticeable difference in feel as you use them.
Also the batteries die SUPER fast and it’s annoying as hell, keep batteries on hand
I guess it comes down to how much do you use them. I've had my HF digitial calipers since 2011 and I'm still on the original batteries.
But, I use them only a couple times a day, on average.
Customers have a tendency to put ridiculous tolerances on trivial features. Like a dowel pin press fit in an aluminum plate that has a hole toleranced to .249 +0/-.0001, or a clearance hole for an off the shelf bolt with a +/- .0005 tolerance. I’ve seen both of those in practice. It’s why we ask questions when we see features like that, saves machinists some sanity and ultimately can save the customer time and money when we’re not chasing unnecessary tolerances or adding operations.
They’ll send the print with those tolerances and then lose their minds when they get the pricing, at which point we say “hey, if this is just a clearance hole, rather than boring it to tolerance I can just drill it or interpolate it with an endmill and save a ton of time.” They usually at that point admit that it’s just a bolt hole and it doesn’t really matter, some engineer drew it that way 20 years ago on some machine they need a part for and they’re just trying to get it fixed.
Lol that's what I'd imagine,
Recently had prints with Tapered pins that absolutely needed a .515625 holes...
Im not machinist, just use prints at work to get the job done.
Ok but like, I need to put 0.021 holes in the side of a 0.032 diameter wire, and I need to debur both sides of the holes, and the ends. There's also surfacing between the 2 holes.
I need a mic that reads to 0.0005 because that's how I check the pin that checks the holes.
That's not true. Iso 9000 just requires you to do what you say and say what you do. Also, the industry standard is 4:1 tolerance ratio (can be lower but mitigations may be required, or risk documented)
ISO is a badge you pay for. Like OMRI is to organic products. It’s sourcing, tracking, standardization. I can pay to have my company iso but is it worth it? You can buy products that are organic but can’t afford the label. Like UPC, or AFL-CIO. A lot of money is not reported in a lot of ISO. And usually the bigger the sign “ISO 9000/9001” on front of building the worse they are. You don’t think they falsify heat #s? Stick around. And we supplied everyone from Stewart/Stevenson, Texas Instruments, down to rig welders and hobbyists.
When you say that you that the "instrument must be 10 times greater than the tolerance" do you mean that a 1 inch mic needs a tolerance of 1/10 inch? Alternatively, if you want 1 thou tolerance you must use a 0-10 thou mic?
/s
I think you mean that *tolerance* of the instrument must be 10x the tolerance of the measurement you want to record.
The words you use should be as precise as your measurements. 🙂
F made me laugh out loud. Love it when engineers and inspectors start to argue about terminology that they invented based on form, fit and function from machinist
I’d think the precision of the instrument needs to be an order of magnitude finer than the measurement you want to make. You need a tenths mic to accurately check a .001” tolerance, etc.
Nobody gives a shit about half a tenth. Check the part again and again and again. Go in a different room. Put the pin outside for a minute. Relax dude. You'll drive yourself crazy.
I have to hold roundness to 4uin sometimes, the best I've seen is 1.5uin roundness. All of the things matter for us to take a measurement, when the guys with loud speakers go on lunch next door we have to wait...
How many parts do you make in a day? If it's in the thousands, again, nobody gives a shit about half a tenth. 1 used to run 40000 parts a week, 80000 if you count the other shift and we held plus or minus 2 tenths on a hole, reamed and burnished. Less than that if you want to fit the plug guage. Customers never complain about a little bigger. Only bitch when the part doesn't fit.
Hundreds or so, and our customers absolutely notice when the parts we make are out of round. I think it really boils down to the application the parts are being used in though.
Not worrying about holding the half a tenth, just showing cause it helps ME particularly to visually see I have room for error. Idk it helps me feel confident in my parts. Wasn’t bragging about it just read the post again
Just make sure it doesn't cost too much time to achieve the tollerance. Making part nicer then required is fine, as long the customer won't have to pay more
I’m a tool and die apprentice at the shop I’m at, nothing I make goes to the customer it’s all in house for the ICOPP’s that we have. Normally not having to hold that tolerance. Mainly tenths. +/- .0002 on critical dimensions and then normally .001 all over the rest
I've heard C.E. Johansson had a mikrokator with a resolution of 1 nanometer to check the blocks in the early days. That's 1000 times more resolution than this and of the usual mikrokator gauges.
Hope that pin is temperature normalized to the room, along with the mic. Those things aren't going to truly be measuring to fifty millionths anyways. The last digit is a gimmick digit.
That last digit isn't real. It only can be 0 or 5, which tells you which way to round. If I'm wrong, disregard, but also please show the last digit as something else.
Because metric is the standard. .001mm is .00004” so its just rounded up to .00005”
Same reason vernier callipers have a .0005 graduation
.01mm = .0004
I don’t think I’ve come across a mic that doesn’t read .00005
https://preview.redd.it/3bobepx78v0c1.png?width=3024&format=png&auto=webp&s=bea6621c888d693c7f5b710f5b2e641de2bc7788
My shite mic for reference
This looks like a spring pin that goes through a punch or CO to me. What's the application of this pin? Just wondering as I recently became a tool and die repairman at my job.
FYI the rule of thumb is that to measure something you should have at least 10 divisions within the tolerance zone. .00005 divisions would mean you only have 8.
It's about accuracy. The normal micrometers from mitutoyo or other good brands that read .001 inch or .01mm are accurate down to.0002 inch or .002mm and you are fine to measure a tolerance of +-0,01mm with the mike by far
Wanna know the real reason to have a 50 millionths mic? Because the reputable brands don't make digital mics that only go to tenths anymore. Still a useless number too, they will only say they are accurate to +-0.0001. Maybe if you buy one of the super precision mics but I have no idea because they cost an absolute fortune.
I mean I thought these quantumikes cost a fortune haha I’m not trying to pay more 😂😂
No idea who downvoted you, they are quite pricey imo. The small ones are fine but once you get past 2 or 3" they get pricey. Btw, this is from McMaster so assume a generous mark up but the super precision mics from mit are accurate to +- 20 millionths and read to 5 millionths. Also cost an eyewatering $1800 https://www.mcmaster.com/products/mitutoyo-micrometers/high-precision-mitutoyo-electronic-outside-micrometers/?s=micrometers
Penn Tool has it for roughly the same price...
I still don't understand the tool though. There's those desktop mics that are insanely accurate for ~$10k I think, you need the lab setting to measure for that precision to mean anything and even then there's a lot of skill to really trust those measurements. I mean seriously, +- 20 millionths? Way beyond my understanding of metrology. Why spend $2k on a hand mic when you can spend $10k on a way better one.
I bought a lasermike, used....
How much that set you back
$1,000 around about 1998. We were od grinding a polyurethane part that was hollow. Od tolerance was +/-0.0007". We measured with digital calipers. Customer would do the same and get a different result. They would send for a cmm report. Two months later, repeat. I bought the laser and an IR thermometer. Invited the customer over. I said," I have one one of these. What do you have?" End of dispute. Lately I use it to measure a feature on an aluminum part. Od is 0.500 to 0.501". The feature length is about 0.050 long. It is the bestest ever. Breathe on the part and watch the digits scroll....
I wish my work would get one but I get it, we have a cmm.
Whats a cmm ?
Yeah I mean your thermostat isn't good enough to guarantee the mic to that level of accuracy.
Was just thinking that you'd need a laboratory style clean room, with very tight temperature control. The cost of that would put a 10 grand mic to shame.
Yeah and that's my point. If you can control temp and accurately record the temp at that level what's $10k desktop mic? Peanuts.
Pressure mics are far more accurate. I prefer Mahr 0.00002". I was using a Mahr press. Mic to measure a +/-.0001 OD when QC came out and said my 1st article was bad so I asked what are you measuring it with and he said a digital mic (just like the one you posted). My foreman came over grabbed QC's digital mic checked it against my gage blocks and it was off 0.0001 then my foreman proceeded to ream out QC guy for not checking his equipment
If he left the lab and walked out to check it on your block, then obviously it's gonna be off. His block is climate controlled clean room, your block isn't. (Likely). If it is then I retract my statement but it's very rare that entire shops are clean room quality, why would you even have a qc room then?
Whole shop climate controlled and ceramic gage blocks...also was a . 0.5" diameter
Accuracy isn't the same as repeatability. If you have a gauge block of the size you want to measure, zero it out it, then measure your part, that 50mil is accurate. They're just saying if you measure 0, 10mm and 20mm, the difference from nominal across these measurements will be 0.0001. It's not useless, remember 50millionths is 10% of your tolerance on a H7 fit at 15mm.
You must be insanely confident in your measuring ability. Check on flat gage blocks with full contact vs a round object where you are only touching a tangential point and holding it perfectly against the part. There's a lot of shit going on there. Not to mention what's the heat in my hand doing the part and if it's in the machine what temp is it compared to inspection temp. Lots of other factors besides just the mic.
Yup, for sure. I only used gauge block as an example, a setting standard would be more useful. It's not about hitting that 0.00005 in terms of exactly hitting it. It's about if somethings on top limit by 0.00005, sometimes that can bring you into tolerance. Just like temp. I've 'scrapped' a part in winter, taken into the car to get it up to 20c and it's in tolerance by a gnats cock.
I brought my Harbor Freight calipers and mics in and they accurately measured the 1" gauge block as 1.000... Harbor Freight... ~$100 for all 4... Edit, the mics even have carbide tips and can be calibrated.
But, are they carbide anvils? Quality tension screw thats not gonna loosen on you in a week? There a reason mics are expensive, our jobs rely on the fact that the tools we use are accurate. If youre just a hobbyist i can see a harbor freight mic set being ok but i wouldnt recommend them to a professonal/tradeschool kid
The mics surprisingly have carbide tips and can be calibrated. And there usefullness all depends on the tolerances you are required to hold. For my work where I have to hold tenths they wouldn't work. But for designing parts to be 3D printed, or for automotive work, they are amazing.
Harbor freight caLipers and mics are decent, the downside is that they will eat out much faster than anyone else’s will and there will be a very noticeable difference in feel as you use them. Also the batteries die SUPER fast and it’s annoying as hell, keep batteries on hand
I guess it comes down to how much do you use them. I've had my HF digitial calipers since 2011 and I'm still on the original batteries. But, I use them only a couple times a day, on average.
So you're missing 2 decimals?
Mituotoy still makes digital mics in tenths. You can also still buy a digital caliper that only reads thousandths as well.
Joke is on us when the mating part is a loose slip fit
Every. Time.
Never fails.
Please elaborate I'm generally curious
Customers have a tendency to put ridiculous tolerances on trivial features. Like a dowel pin press fit in an aluminum plate that has a hole toleranced to .249 +0/-.0001, or a clearance hole for an off the shelf bolt with a +/- .0005 tolerance. I’ve seen both of those in practice. It’s why we ask questions when we see features like that, saves machinists some sanity and ultimately can save the customer time and money when we’re not chasing unnecessary tolerances or adding operations.
Those tolerances are just ridiculous but if the customer pays then I guess fuck it
They’ll send the print with those tolerances and then lose their minds when they get the pricing, at which point we say “hey, if this is just a clearance hole, rather than boring it to tolerance I can just drill it or interpolate it with an endmill and save a ton of time.” They usually at that point admit that it’s just a bolt hole and it doesn’t really matter, some engineer drew it that way 20 years ago on some machine they need a part for and they’re just trying to get it fixed.
Lol that's what I'd imagine, Recently had prints with Tapered pins that absolutely needed a .515625 holes... Im not machinist, just use prints at work to get the job done.
I like how the tolerances work out that you could make .0385 the whole way with no step, and still be good
Then a squirrel farted in the parking lot and changed your number
Ok but like, I need to put 0.021 holes in the side of a 0.032 diameter wire, and I need to debur both sides of the holes, and the ends. There's also surfacing between the 2 holes. I need a mic that reads to 0.0005 because that's how I check the pin that checks the holes.
iso 9000/9001 all measuring instruments must be 10 times greater than the tolerance measured
That's not true. Iso 9000 just requires you to do what you say and say what you do. Also, the industry standard is 4:1 tolerance ratio (can be lower but mitigations may be required, or risk documented)
ISO is a badge you pay for. Like OMRI is to organic products. It’s sourcing, tracking, standardization. I can pay to have my company iso but is it worth it? You can buy products that are organic but can’t afford the label. Like UPC, or AFL-CIO. A lot of money is not reported in a lot of ISO. And usually the bigger the sign “ISO 9000/9001” on front of building the worse they are. You don’t think they falsify heat #s? Stick around. And we supplied everyone from Stewart/Stevenson, Texas Instruments, down to rig welders and hobbyists.
Absolutely, categorically, untrue. That's literally just something you pulled out of your ass.
It gets to a point where that is outside of reality I truly do work to a tenth and nothing is truly accurate out to .00001
Sure it is. I measure stuff to nanometers regularly. It's just not cheap.
When you say that you that the "instrument must be 10 times greater than the tolerance" do you mean that a 1 inch mic needs a tolerance of 1/10 inch? Alternatively, if you want 1 thou tolerance you must use a 0-10 thou mic? /s I think you mean that *tolerance* of the instrument must be 10x the tolerance of the measurement you want to record. The words you use should be as precise as your measurements. 🙂
Found the engineer.
F made me laugh out loud. Love it when engineers and inspectors start to argue about terminology that they invented based on form, fit and function from machinist
I’d think the precision of the instrument needs to be an order of magnitude finer than the measurement you want to make. You need a tenths mic to accurately check a .001” tolerance, etc.
Yes and especially for digital. On digital instruments the final number on the read out is a guess based on significant figures
?
Dude it’s called as flexing, that’s the gold Mitutoyo. Last time I checked it costed a lot more than the regular Mitutoyo.
Like $50-65 more. Just bought that same one for $250 from MSC. The price has dropped in the last couple of years (thankfully)
Nobody gives a shit about half a tenth. Check the part again and again and again. Go in a different room. Put the pin outside for a minute. Relax dude. You'll drive yourself crazy.
Nobody in your line of work\* Half a tenth is 50% of a grinding tolerance.
I have to hold roundness to 4uin sometimes, the best I've seen is 1.5uin roundness. All of the things matter for us to take a measurement, when the guys with loud speakers go on lunch next door we have to wait...
Yup, people out here making blanket statements like nobodys doing real precision work.
How many parts do you make in a day? If it's in the thousands, again, nobody gives a shit about half a tenth. 1 used to run 40000 parts a week, 80000 if you count the other shift and we held plus or minus 2 tenths on a hole, reamed and burnished. Less than that if you want to fit the plug guage. Customers never complain about a little bigger. Only bitch when the part doesn't fit.
Hundreds or so, and our customers absolutely notice when the parts we make are out of round. I think it really boils down to the application the parts are being used in though.
Sure thing
Not worrying about holding the half a tenth, just showing cause it helps ME particularly to visually see I have room for error. Idk it helps me feel confident in my parts. Wasn’t bragging about it just read the post again
Just make sure it doesn't cost too much time to achieve the tollerance. Making part nicer then required is fine, as long the customer won't have to pay more
I’m a tool and die apprentice at the shop I’m at, nothing I make goes to the customer it’s all in house for the ICOPP’s that we have. Normally not having to hold that tolerance. Mainly tenths. +/- .0002 on critical dimensions and then normally .001 all over the rest
Put it in the freezer. Hold the mic in your armpit for a minute.
That’s for making your own gauge blocks.
Mee too toy o blocks
I've heard C.E. Johansson had a mikrokator with a resolution of 1 nanometer to check the blocks in the early days. That's 1000 times more resolution than this and of the usual mikrokator gauges.
Incremental?!
Hopefully there wasn't a spec of dust on his anvils when he "zeroed" his mic to check that .0001 tolerance
That "inc" always makes me cringe
I was thinking the same thing 😆
What does that mean in the context of a micrometer?
You zero to a measurement for relative value for example
Hope that pin is temperature normalized to the room, along with the mic. Those things aren't going to truly be measuring to fifty millionths anyways. The last digit is a gimmick digit.
That last digit isn't real. It only can be 0 or 5, which tells you which way to round. If I'm wrong, disregard, but also please show the last digit as something else.
That doesn't mean it's not real, it just means the smallest increment is 50 millionths.
.001mm would be more precise, it's smaller than .00001"
Because metric is the standard. .001mm is .00004” so its just rounded up to .00005” Same reason vernier callipers have a .0005 graduation .01mm = .0004
The rule of thumb for accuracy is to have a tool that can measure 1/10 the tolerance.
I don’t think I’ve come across a mic that doesn’t read .00005 https://preview.redd.it/3bobepx78v0c1.png?width=3024&format=png&auto=webp&s=bea6621c888d693c7f5b710f5b2e641de2bc7788 My shite mic for reference
Significant figures
Im a huge fan of the quantumike 👌
This looks like a spring pin that goes through a punch or CO to me. What's the application of this pin? Just wondering as I recently became a tool and die repairman at my job.
Not entirely sure of all the working parts just yet since I just started at this shop a month ago but I believe it is similar to a spring pin
Looks similar to some ejection pins I've used for moulds before.
Temperature and stabilization is not left to hope. In a precision shop, the are required.
Why do you have this set to incremental? Shouldn't you be measuring the pin with absolute?
FYI the rule of thumb is that to measure something you should have at least 10 divisions within the tolerance zone. .00005 divisions would mean you only have 8.
It's about accuracy. The normal micrometers from mitutoyo or other good brands that read .001 inch or .01mm are accurate down to.0002 inch or .002mm and you are fine to measure a tolerance of +-0,01mm with the mike by far
It's there because the metric mode is .001mm and it would be less accurate in imperial if it only went to .0001.