Questions tagged [measurements]

Measurements, instrumentation, calibration and metrology.

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1answer
22 views

off-scale torque measured - what is my torque arm?

I have assembled a benchtop torque measurement stand for evaluating electric motor and controller efficiency. The motor is 49kV , 5kW brushless outrunner. Input power reading is taken from motor ...
3
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1answer
31 views

What's the most practical way to measure angular velocity for small rotations?

I'm looking to measure the angular velocity of an arm as it moves. It seems to be a difficult thing to research, since the term 'angular velocity/frequency' is usually reserved for other areas of ...
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2answers
39 views

Measuring viscosity with tools other than viscometer

I would like to measure viscosity, but do not have access to a viscometer. If possible, I would like to avoid having to purchase one. I have access to many other flow measuring devices, including ...
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3answers
49 views

Cutting a larger circle on center of a smaller circle

At work, we cut a 6" hole in the wall for a duct. Later we decided we now want a 10 inch duct in the same place. what tricks are there to center the larger hole over the center of the smaller hole if ...
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1answer
24 views

Bolt circle indication on angled ellipse

Ok so I am a machinist, not an engineer, but figured someone here might be able to provide some insight into my situation. The part is 2.75" diameter and is on a 3.3* angle in the X axis on my mill. ...
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1answer
28 views

Whats a reliable way to measure the amount of rope going out of a coil?

I am an undergraduate researcher and I am working at enhancing a calibrating system for a hydrographic surveying system that my supervisor uses on his hydrography course. The rope is used to lower a ...
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0answers
42 views

Which imperial units of measurement use vulgar (simple) fraction numbers?

All values of metric units are expressed in decimal or scientific notation. Some imperial units, use fraction numbers as primary notation (3/4" for 0.75 inch). As far as i know, only inch and foot ...
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0answers
14 views

What pressure value to use for Poiseuille's equation?

If using a mass flow meter with a annular gap to produce laminar flow and the reading across the restriction is 871 Pa, is this the correct value to use for dP in the Poiseuille equation? Or must that ...
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1answer
18 views

Measuring wire damage using strain gauges

We need to determine the physical damage in some area of overhead lines that can't be inspected visually. The damage's in general caused by short circuit and air pollution (mostly sulphur compound). ...
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0answers
13 views

VNA Measurements: Dielectric Constant and Loss Tangent

All, We have a small legacy application which calculates dielectric constant and loss tangent from sample thickness, frequency, and Q. We have the built executable but not the source code. The Q ...
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0answers
25 views

How much does loading a load cell in other directions than the direction it was designed for effect the readings?

I am looking into using this TAL230B miniature type load cell to measure forces in x and y direction. The normal sensor loading is displayed in image 1. What is the effect of loading them as in image ...
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0answers
15 views

Strange offset on oscilloscope channel

I've a Rigol DS2072A. It works great except for an offset problem that I noticed the past few days. Channel 2 always shows a DC offset. This is independent of any settings such as channel coupling, ...
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5answers
87 views

Plumbing Imperial units confusion - 3/4" is supposed to be around 19mm, right?

I'm really confused. I've only ever used metric in my life. Recently I'm trying to build a IOT device and there is plumbing and water involved. I was looking for a 19mm fitting, but on Amazon and ...
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0answers
16 views

How to identify trip coil circuits of Circuit Breaker?

Recently I've encountered Cercuit Breaker without any control circuit diagram. Just many teminals and wires without any tag! I want to do timing test of CB. How can I identify trip coil circuit?(Using ...
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2answers
31 views

How can I get the horizon or vertical length of the uneven object?

Just like the picture shown I want to have the length from the front end to the windshield in horizon, and want to have the length from the lowest point to the highest point of the hood in vertical. ...
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3answers
135 views

Confused as to how to read this caliper

Here is a picture of a caliper that I found: Calipers are such basic tools, but I have trouble understanding how they work. Here the main scale says "mm" at the end, and the Vernier scale says "0....
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0answers
20 views

How to measure the inertia of an object using a motor

first time on this board even if I've been lurking for a while. I'm a tennis racquet technician and, for the sake of saving some money and just for the fun of it, I'm trying to build a machine that ...
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1answer
80 views

Must MSA (Measurement System Analysis) be re-performed after annual instrument calibration?

I'm working in an automotive company that must follow IATF (International Automotive Task Force) requirements. I administrate a test-bench that performs RF (radio frequency) tests using an ...
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1answer
46 views

What measurement accuracy/precision is required to detect a 10% relative change in the measured quantity

I'm trying to design a measurement system, the primary objective of which is to reliably detect a 10% change in the the volume of fluid flowing through a pipe. I'm struggling to come up with a ...
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1answer
279 views

What are functional and manufacturing datums

Can somebody please explain what is ment by functional datum and manufacturing datum, with respect to dimentioning and tolerancing.
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2answers
37 views

How to measure number of strokes in a small space

I have read about a device called drumometer, which measures the number of strokes of hitting drum stick. I think this is almost the same, but instead, I would like to measure the number of strokes/...
2
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0answers
35 views

Maintaining constant speed of a CVT engine during a slope

I am not sure if this question is related to this community. But nevertheless. I work on CVT engines, I had a new idea of modifying my controller during a slope or a gradient on the road so that the ...
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1answer
82 views

How can I measure the coefficients of friction of pulleys?

I have to study several industrial pulleys made for lifting heavy weights. It is important to select one which has a low coefficient of friction because the system is based in a hoist and several ...
2
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1answer
570 views

What is the difference between direct and indirect reading instruments

I need to know the difference between a direct and indirect reading instrument. Would a caliper be a direct and a gauge block be indirect? Is a direct instrument something with a variable measurement ...
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1answer
29 views

Typical range of a small hole gauge.

I want to get this out there. What is a typical and common range of a small hole gauge?
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1answer
64 views

How accurate must my gauge be?

Is there a general rule of thumb for how accurate a gauge should be in compared to the parts being checked? In my chemistry class, I remember making standards where the instrument needed 1 more ...
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1answer
61 views

Measuring vs gauging

How would one describe the difference between measuring and gauging? As I understand it at my company, we use a fixed tool to gauge something, but we will use a set ...
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1answer
27 views

What device would you use to set angles in two plates?

I am studying gauges for measurements and I can't find the answer to what device I would use to set angles in 2 plates.
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1answer
38 views

Can strain gauges radially be mounted on 8 mm diameter shaft for torque measurement for effective result?

I need to measure a torque on an 8mm shaft of an electrical motor on a prototypical device. The expected torque is ~15 Nm and for the data processing I intend to use an Arduino. One requirement which ...
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1answer
196 views

What is the engineering standard for filenames with fractions and inches?

I need to save some engineering files that need the thicknesses in the filename. Windows hates "/" or "\", so I can't use a simple fraction. Symbols like this... ⅓, ⅔, ⅕, ⅖, ⅗, ⅘, ⅙, ⅚, ⅛, ⅜, ⅝, ⅞ .....
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1answer
41 views

Measuring beats/bounce in a closed cubed glass

Suppose that we have a $2$ by $2$ by 2 $cm^3$ closed box, made up of glass, with thickness $0.1 cm$. Yes, it is a very small box. Let's say in that box there is a ball (also made with glass) with ...
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2answers
40 views

High impact force sensor?

I have a small table-like platform with two legs. Underneath each, I need to measure the amount of force. I want to use the difference between the two force measurements to estimate the platform's ...
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1answer
160 views

Strain gauge placement to measure a twisting beam

Where is it best to place a strain gauge to measure the twist of a beam? And what type of gauge is best? In my application, I have a small metal part which experiences a twisting and bending force. ...
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1answer
33 views

Can foil strain gauges measure strain normal to the plane of the sensor?

I'm wondering if anyone in the community has experience with foil strain gauges used to measure strain components that are normal to the plane of the sensor? If the strain gauge were pressed between ...
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4answers
1k views

Methods to measure diameter

I want to measure a tube's diameter with a precision of about 0.1 mm. I have a caliper but sadly the tube is wider than my tool. I would like to know what methods exist to precisely measure a ...
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1answer
16 views

Maximum height view-able in the box when looking through slit

The problem is illustrated in the picture below. A viewer looks through a slit and into a room. The problem is to find the maximum height of the wall in the room that the viewer can see if they are ...
0
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1answer
296 views

what is 1P frequency in rotor (wind turbine)?

In wind turbine, Is the number of revolution taken in 1s is called 1P frequency? If not, is it possible to find the 1P rpm from rpm measured for 1 hour (that is, I have 60 rpm data points from ...
2
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2answers
347 views

How do solar balloons work at high altitudes?

I am interested in the challenges that Solar Balloons face when flying. For example, the high altitude could cause drastic changes in: Wind speed Temperature Moisture How does the unique design of ...
2
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2answers
76 views

In what cases are the roughness values Rt and Ra used?

Roughness measurement instruments output those two values, where Rt is the distance between the top of the highest peak and the bottom of the lowest valley, and Ra is the average distance of every ...
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1answer
63 views

How do I measure mercury in a graduated cylinder?

Convention says to measure at the bottom of the meniscus, but I think the cohesion/adhesion balance of mercury results in it "bulging out" Do you measure at the top of the bulge (near the center) or ...
3
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2answers
684 views

What does 12 bit resolution mean?

I'm looking at this inclinometer and in the features it says "12 bit resolution." I'm looking for a resolution of up to a 1/10th of a degree but don't understand what the 12 bit resolution means.
3
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3answers
390 views

Rule of Tens/Ten to 1 Rule in Measurement and Inspection

I'm trying to clarify my understanding about the requirements [read: best practices] for measurement resolution and measurement confidence. The "Rule of 10s" is a commonly tossed around guideline ...
4
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1answer
230 views

How do you convert “kps” to Pounds per Square Foot (psf)? [closed]

I'm looking at a soil bearing capacity report, which has a column labeled "kips" and the values are followed by "kps". A "kip" is 1000 pounds, but I'm not sure how to convert from "kps" to psf. The ...
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1answer
33 views

AirFlow Measurement

I'm a software developer, who wants to create a monitoring system for an industrial airflow system. The airflow of the system is huge - between 15 and 20 cubic liters per minute. Here is my problem, ...
2
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0answers
21 views

Finding liquid viscosity

I'd like to calculate the viscosity of a liquid in a container systematically (and feed the results back to a computer). I only have basic knowledge of physics and mechanics. I think that a motor ...
0
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3answers
152 views

Wind measure with strain gauge

I'm trying to build my own weatherstation for my home, I want to measure temperature humidity and wind strenght and direction. For the wind I have a question. I want to measure the wind with a ball on ...
2
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2answers
64 views

Would connecting 100's of small telescopes into one huge telescope make for a significantly better telescope?

Not sure if this is a Physics related or Engineering related question, but imagine that we would take 100's of small hobby telescopes and somehow managed to point them all at the same point in the sky ...
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1answer
618 views

What is best sensor & method to measure human height?

My application needed to measure human height on a standing kiosk. I need to attach the sensor on kiosk ceiling type top. I used different kind of ultrasonic sensor for this purpose but nothing ...
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1answer
74 views

How would I measure this battery circuit with a multimeter?

The wire is attached to the bottom of each D battery. I already know that I have to put the bottom of the light bulb on the positive side of the battery. My multimeter looks like this: I'm not sure ...
2
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2answers
34 views

Measurement of immobile curved surface

I'm not entirely sure if this is the right place to ask this, so apologies in advance if it doesn't belong. I have a curved surface with many small, irregular holes in it that I would like to measure....