Gage blocks
Re: Gage blocks
To add to your errors? I recently found out from a Mitutoyo video that gauge blocks can change up to 1 micron per inch per year. No explanation was given for why that happens only that it can. For most of us I'd say that could be just about ignored. The good part about analog gauges is in some cases interpolation can sometimes be used to split the divisions. Digital usualy can't do the same. But the equipments repeatability and the additional uncertainty of your measurements beyond what accuracy the equipment was designed for starts becoming a real problem as far as then fully trusting what your reading. It should at least indicate there might be a measurable deviation with the set up you have and being able to double the error by swapping the blocks position. It's still pretty fussy work though.
After my comment earlier in the thread, I realized I have more than just calipers and micrometers to measure. I now have several cheap import DROs and a collection of old/worn equipment and cheap import equipment, who knows what errors there are in the leadscrews now...
They're still not something I'd use more than a few times, but they suddenly look more useful.
Re: Gage blocks
For what ever reason, folks seem to think of metals as being stable--benign---unchanging. Nothing could be farther from the truth. Gauge blocks are, typically, subjected to heat and cold cycles to help stabilize them. There's some serious activity going on in metals. We just can't see it. Some is quite obvious---like movement resulting from breaking the surface, or large stock removal from one face, with little or none from the opposing face.
You have to abandon normal thinking when it gets down to miniscule measurements.
H
Wise people talk because they have something to say. Fools talk because they have to say something.
Re: Gage blocks
I seem to remember hearing (years ago) that the platinum standard that defines the Meter has changed in length since it was manufactured.
So now there is a standard based on some wavelength of light.
Am I remembering this correctly?
~RN
So now there is a standard based on some wavelength of light.
Am I remembering this correctly?
~RN
Re: Gage blocks
Even if the erstwhile platinum standard maintained its length perfectly, it still wouldn't be as useful as the present system...
The Geneva Conference on Weights and Measures has defined the meter as the distance light travels, in a vacuum, in 1/299,792,458 seconds with time measured by a cesium-133 atomic clock which emits pulses of radiation at very rapid, regular intervals.
The problem with the platinum/iridium standard is that it's impossible to make highly accurate copies of it to use in all the remote locations that need a standard. The errors incurred in making the copies would exceed the length changes of the bar over time.
OTH, the speed of light in a vacuum is a well known universal constant. A metrology lab anywhere can set up a precise standard meter measurement system without the need to go to Paris and attempt to copy a metal bar.
If you're wondering about the odd length of time, the speed of light is 299,792,458 meters per second so, in the indicated time interval it would travel exactly one meter.
In a similar approach, the second is defined to be exactly 9 192 631 770 cycles of a cesium atomic clock. Again no copying of a standard is involved so the errors associated with that process are eliminated.
Of the three essential elements of a measuring system, distance, time and mass, only mass still employs a physical standard, currently stored in Paris. Once we physicists puzzle out exactly what mass is, the hope is that an atomic standard for mass can be defined and the physical standard put away as a display in a museum.
Regards, Marv
Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz
Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz
Re: Gage blocks
mklotz wrote: ↑Thu Sep 20, 2018 10:01 am If you're wondering about the odd length of time, the speed of light is 299,792,458 meters per second so, in the indicated time interval it would travel exactly one meter.
Of the three essential elements of a measuring system, distance, time and mass, only mass still employs a physical standard, currently stored in Paris. Once we physicists puzzle out exactly what mass is, the hope is that an atomic standard for mass can be defined and the physical standard put away as a display in a museum.
I guess you could say the speed of light is only 18 kromulen units per second, so naturally the kromulen is defined as the distance light travels, in a vacuum, in 1/18 seconds with time measured by a cesium-133 atomic clock that emits pulses of radiation at very rapid, regular intervals...
Have the powers yet released the "New" kilogram?
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Re: Gage blocks
Are yous suggesting my method will not provide any meaningful results?Harold_V wrote: ↑Thu Sep 20, 2018 3:21 amFor what ever reason, folks seem to think of metals as being stable--benign---unchanging. Nothing could be farther from the truth. Gauge blocks are, typically, subjected to heat and cold cycles to help stabilize them. There's some serious activity going on in metals. We just can't see it. Some is quite obvious---like movement resulting from breaking the surface, or large stock removal from one face, with little or none from the opposing face.
You have to abandon normal thinking when it gets down to miniscule measurements.
H
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Re: Gage blocks
I'm not smart enough to even understand your method.ctwo wrote: ↑Thu Sep 20, 2018 2:53 pmAre yous suggesting my method will not provide any meaningful results?Harold_V wrote: ↑Thu Sep 20, 2018 3:21 amFor what ever reason, folks seem to think of metals as being stable--benign---unchanging. Nothing could be farther from the truth. Gauge blocks are, typically, subjected to heat and cold cycles to help stabilize them. There's some serious activity going on in metals. We just can't see it. Some is quite obvious---like movement resulting from breaking the surface, or large stock removal from one face, with little or none from the opposing face.
You have to abandon normal thinking when it gets down to miniscule measurements.
H
H
Wise people talk because they have something to say. Fools talk because they have to say something.
Re: Gage blocks
Perhaps because the illustrations are on the previous page of the topic and you did not see them? It is quite simple, and that is about all I could come up with. The next step for me alone would likely be simple blind faith.
Last edited by ctwo on Thu Sep 20, 2018 6:41 pm, edited 1 time in total.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Re: Gage blocks
This would get you close...
https://www.ebay.com/itm/Van-Keuren-Lig ... xyPc5SB3P1
Van Keurens answer to the P&W Supermicrometer.
https://www.ebay.com/itm/Van-Keuren-Lig ... xyPc5SB3P1
Van Keurens answer to the P&W Supermicrometer.
Glenn
Operating machines is perfectly safe......until you forget how dangerous it really is!
Operating machines is perfectly safe......until you forget how dangerous it really is!
Re: Gage blocks
That tool has a broad application. My first thought is to make one.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Re: Gage blocks
If you make the wheel big enough, you could measure angstroms.
I have one of those direct-reading tenths micrometer heads. I thought of making a bench mic out of it.
I thought if I put a vernier on it, it would measure a tenth of a tenth.
Steve