# Tag Info

6

I'm not sure of the specifics of your problem, it seems to be relatively straightforward to me. I have previoulsy considered addressing the subject of measurement errors with schoolchildren in the following manner - it may be of help to you and your audience or change in subject may confuse and distract them from your topic, that's up to you to decide. Step ...

5

Anisotropic etching is a linear process, like welding, so presumably the units would be distance per time. Unlike welding it is at a small scale. See this slideshare. In this case units are Angstroms per minute. One Angstrom is $10^{-10}\ \textrm{m}$, indicating the process is on an atomic scale. Since it appears to be used for integrated circuit fabrication,...

5

Gage (gauge) thickness are somewhat arbitrary. Take for example the table below, excerpted from the AISC Steel Construction Manual, 14th Ed.: You can see that gage thicknesses vary depending on material and coating but are approximately the same for a given gage number. This PDF references the following for different material gages: Aluminum (no official ...

4

You want a wavelength meter if you have one or otherwise a spectrometer. In more detail: A wavelength meter uses an interferometer to measure wavelength. It can measure wavelengths very accurately. A spectrometer measures a spectrum, that is intensity vs wavelength. The wavelength at the peak intensity is what you are looking for. A spectrophotometer is ...

4

MWijnand is correct that what you are looking for is an altimeter. However, you will not find anything that could provide you with accuracy anywhere near the scale of a correctly used total station. From my experience you would be lucky to find something which would be able to find precision down to the 5' of elevation and accuracy with this device would ...

4

For the Maths of calculating uncertainty the standard document is the GUM. Which describes all the maths but can be somewhat unclear if you don't already have some idea how it is supposed to work. Depending on your current level of expertise there are several good introductions to uncertainty calculations. I would recommend A Beginner's Guide to Uncertainty ...

3

Alhtough this answer should be awarded to Pete, because he has spotted it first. The accelerometer has a sensitivity of 5%, which corresponds to 100[mV/g]. what you are measuring is 0.1[m/s^2], which is about 0.01g. So the actual signal you should be receiving from the piezoelectric accelerometer is about 1[mV], which is quite low. Now, if you see the ...

3

The "three plate" method has been used as the basis for precision manufacturing/inspection. This is a decent summary, it's pretty ingenious and only requires dye and abrasives. This will teach you everything you need to know and then some, "Foundations of Mechanical Accuracy".

3

The only way to determine the accuracy to which any measuring device provides measurements is to calibrate it against a device of known accuracy and known errors for measurements. You technique is partially correct; don't just do the error measurement for the limits of the device as one population or sample bin. This is because measurement errors are not ...

2

There are two ways to do it. The old way The traditional way is to develop a set of somewhat arbitrary rules based on the errors you manually classify. You filter out non-monotonicity (easy), identify resets (easy), and try to spot other bad values (trickier). That gives you a set of values to mark as missing, and then you analyse the rest of the data. This ...

2

There's a handy-dandy table here: Office | Residential/hotel | Function Unknown or Mixed-Use floor-to-floor height (f) 3.9m | 3.1m | 3.5m Entrance lobby level floor-to-floor height 2.0f = 7.8m | ...

2

In this situation, you might do just as well to use a U-tube manometer. Is some respects, this is a sort of dead-weight tester where the fluid itself is the dead weight. In this device pressure is determined from the difference in height between two connected volumes of fluid. Usually this is just a transparent tube bent into a 'U' shape, placed upright in ...

2

Your approach is broadly correct. If you are only interested in the accuracy of your system you probably want to use something like the maximum error. Your accuracy is then +/- Max error with the assumption that real errors are uniformly distributed within this range (a uniform distribution will often be an overestimation but is a simple option when no ...

2

Most gauge systems like SWG aren't linear and are based on a volumetric or cross sectional area system of some sort. In the case of wire gauges it is usually derived from the number of drawing operations required to produce a particular size of wire, so the gauge number is not proportional to the diameter but rather inversely proportional to the cross ...

2

BFSL (Best Fit Straight Line) is the same as BSL (Best Straight Line). It is calculated from the calibration's extracted data, where the manufacturer test the sensor for several known input values (in this case, pressures). Once these calibration points are measured, they are approximated with a straight line (least-square method) and the BSL value is an ...

2

Remember that a rule of thumb is just that, a rule of thumb. It is not a hard specification, so in some sense there really is no right answer here. It is a good starting point, but to determine what is acceptable for your system you need to balance three things 1) What is the cost of a false positive? i.e. what is the consequence if a perfectly ...

1

You must first calibrate your three devices to give the same result against each other for at least two different input values. A one-point calibration only assures that they have no baseline constant offset relative to each other for the given input. Two points assures that the devices are linear in the same way over the calibration range. Three points and ...

1

You are using a piezo electric accelerometer. There are always always always offsets and low frequency noise on a piezoelectric accel. Depending on the charge amp, anything below about 3 hz is meaningless. Just high pass filter the signal to get rid of it. If you need to read below 3 hz then you shouldn't use a piezoelectric. Use mems or piezo resistive in ...

1

Correct. The rule of thumb is multiply your tolerance range by 10% (or divide by 10) to get the minumum resolution of your measuring device. Regarding the 12.96 tolerance range because more precision is applied to the dimension, two decimal places, or .01mm precision, you need a measuring device 10x that precision to be accurate. So a device with .001mm ...

1

It's important to note that "Rule 1" is considered to apply automatically when referencing ASME Y14.5, but not necessarily so if using the ISO version. Nonetheless, the concept of Rule one extends the size tolerance to be inclusive of the FORM tolerance. In other words, if the pin was as it Maximum Material Boundary (MMB) - it's largest size - it would ...

1

there is a whole genre of "square block" videos on YouTube by various machinists. The standard tool seems to be the lathe. But really, you are asking how to set up a machine to be perpendicular. apropos, video for your edumatainment

1

The fundamental problem is: how do you reject the optical signal from solids or liquids "behind" the air mass you want to measure? The esoteric methods reported in : https://pdfs.semanticscholar.org/9ccd/6df082576a620a2a89f8e6b7203186e6b08c.pdf , http://www.mdpi.com/1424-8220/18/1/72/pdf may work, because they indirectly measure air temperature rather ...

1

The best metric of confidence in making measurements is the overall relative uncertainty of the measurement. Two factors contribute to uncertainty for a measuring device. One is the calibration uncertainty. This is an offset or bias. The other is the device or scale uncertainty (precision). Consider a force-gauge with a spring. The spring constant depends ...

1

I was on a team of quality engineers (but not one of the experts), and they had a visual where they used a 2d plot where X axis was first measurement and Y was second measurement of the same observable feature. They would repeat the measure/remeasure and create what they called a "sausage chart". They would eliminate the outlying 2% of samples and draw a "...

1

Have you considered using a laser level device? I've seen estate agents (realtors) use these for measuring the size of rooms. You could point one at the ground and it would give you your elevation. The advantages are relative cheapness and reliability, the main disadvantage is it requires line-of-sight.

1

GPS would be the best solution provided the desired measurement location has access to multiple satellites (not in a cave, steel building, deep canyon, etc). Like Air mentioned, smartphones have built in GPS modules that will work well in many situations. This gps world article estimates consumer grade smartphone resolution to be 2 to 10 meter depending on ...

Only top voted, non community-wiki answers of a minimum length are eligible