Questions tagged [measurements]

Measurements, instrumentation, calibration and metrology.

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75 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
1k 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
80 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 ...
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2answers
39 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....
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2answers
326 views

Weight Sensing Problem: Need to detect 10kg load down to milligram accuracy

So I need to build some type of scale where one can place four 600mL beakers on it and measure out its weight down to a milligram level of accuracy. I'm doing this so I can dose a very small amount of ...
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1answer
107 views

Convert angular acceleration from (S/100Hz) to (RPM/s)

I'm writing a script that converts from a customer's preferred unit of $\frac{RPM}{s}$ and a device's input/output of $\frac{s}{100Hz}$ My Logic is as follows: Converting $\frac{RPM}{s}$ to $\frac{s}{...
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1answer
53 views

What thread could this camera motor be?

Firstly, I am sorry that the title of this question isn't helpful. I have bought these motors for a project: 5V 7mm 2 Phase 4 Wire Stepper Motor I assumed that the 1.7mm diameter threaded shaft ...
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1answer
1k views

Selecting edge of a circle in Solidworks

When I am drawing things (Assembly) in SolidWorks, on some parts which I work on, I can select the edge of a circle and then measure the dimension to a line, like shown below: But the problem is that ...
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2answers
88 views

How to describe or call this part?

I want to build my own 4 point bending tester. First, I need to see what parts are available for sale. Can anyone tell me if the circled L-shaped part has a name I can use to search with, and if so ...
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1answer
52 views

What are the electronic readout versions of Dial Indicators called?

These items: https://www.parktool.com/product/dial-indicator-gauge-set-for-ts-2-2-and-ts-2-truing-stands-ts-2di are mechanical gauges with roller tips that are intended to measure deviations from true ...
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2answers
69 views

Is there a way to distinguish between U.S. Customary and British Imperial volumetric units?

I am used to the metric system where everything is simple and consistent. I can do quick conversions between metric and imperial in my head, but especially when it comes to volumetric measures, I ...
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1answer
359 views

How can I detect black spots?

I am researching about ways to continuously determine black spots (size 50+ micron) in our product stream. This stream consists of imperfect spherical polymer beads (size 3 mm) of different materials (...
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1answer
104 views

Automated valve for testing module

I work frequently with materials sensitive to oxygen and moisture, within a glove box. However, there are frequently times I want to move these samples from the glove box to a scanning electron ...
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1answer
86 views

How would a person be able to rebuild modern machining? [duplicate]

In a post apocalyptic setting, rebuilding humanity's technologies would be a pretty prevalent idea. I am in the process of becoming a mechanical engineer. Something that I have noticed is most classes ...
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1answer
36 views

Established Patterns and Designs for Measuring Powder by Volume

I'm not a mechanical engineer so please be patient with my descriptions and question. I am working on a design for a device that needs to measure out different amounts of powders by volume (not ...
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3answers
113 views

Making precise, intricate measurements

What's the best way to precisely measure intricate mechanical parts? For example, notice the tiny differences between the pitch in these two threads, and the tiny variations in external width of the ...
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1answer
71 views

How much does a wall stop sound?

So I have this problem, every Sunday we have about 200 kids come over to our house in town, and they make a LOT of noise. We also have mildly nice neighbors that do not like noise Sunday afternoon ...
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1answer
33 views

How can I determine pressure leakage in a pneumatic system?

I am an engineer currently designing a system in which the leakage of a hose is tested. The system consists of the following components: An air data system used to generate a pressure inside the hose....
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4answers
116 views

How to detect whether a bus is in motion or not

I am a university student and I need some help in a project. For the past few years now, many accidents have occurred whereby in overcrowded buses, passengers are accidentally propelled from the back ...
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0answers
394 views

Detergency and dispersancy

Abstract:The detergency property in oil comes from a chemical additive called detergent which has a property of preventing the deposition of carbon deposits and wash it away. There is also this ...
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3answers
2k views

Experimental method to determine the centre of mass for 3D object

I have to determine the centre of mass for a 3D object (bounding box: approximately $0.30 \text{ m} \times 0.20 \text{ m} \times 0.10 \text { m}$) that is not regular and does not have a uniform ...
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1answer
530 views

Calculate shear stress unit conversions [duplicate]

The formula for newtons to pascals is below. $$1\text{ Pa} = 1\text{ N/m}^2 = 9.81\text{ kg/m/s}^2$$ I am trying to solve this problem but the units are a bit confusing. I want to get the shear ...
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1answer
106 views

Maximum Tensile strength confusion [closed]

Is the maximum tensile strength a property of a material ? If it is so then suppose I am given the maximum tensile strength of two flat spiral springs to be $30MN/m^2$ and I have to find the ...
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0answers
53 views

Is there a 5% range CO sensor with a response rate higher than 1Hz?

I'm building a portable emission analyser which measures emissions from a tailpipe, to aid in troubleshooting and tuning an engine. For this, I need a $\text{CO}_{2}$ , a $\text{CO}$, and an $\text{O}...
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1answer
65 views

Thermistor - Steinhart-Hart Coefficients

In order to identify Steinhart-Hart coefficients for a thermistor, three known temperatures may be used to find three resistances. What is the best way to choose these temperatures to calibrate ...
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4answers
757 views

How to measure the pressure inside a bottle rocket?

I'm making a pressurized bottle rocket out of a plastic bottle, vinegar, baking soda and a cork. When the vinegar & baking soda react in the closed bottle, the pressure builds up but i want to ...
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1answer
661 views

How can I accurately measure the actuation force of small buttons (<1cm diameter) using home equipment?

I'm trying to measure the actuation force of buttons on the Playstation Vita, in preparation of building an external device that presses these buttons automatically. Specifically, I'm trying to ...
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2answers
313 views

How to measure above 100K RPM?

I'm trying to measure the rotational speed of a turbocharger, but the laser tachometer I have can only measure up to 99,999 RPM and it isn't enough (display starts to output letters) and devices that ...
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1answer
516 views

In what context is 50 threads per inch common?

I recently found a loupe with a thread pitch reticle displaying common UTS thread pitches... except that rather than 40, 48, or 56 it has a 50. What would this be used for? It doesn't appear to date ...
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0answers
59 views

Measuring Helix Angle

What is the best way to measure the helix angle of a helical cut gear? I have a sun gear from a planetary set that I would like to have custom made but I'm not sure the best way to get the helix angle,...
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2answers
918 views

Read holes schematic drawing notation. How to? Particular case

I am asking here for your help and advice on how to read holes schematic notations. On the attached picture I've marked with a green color part of notation that I don't know how to read / understand. ...
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0answers
32 views

Measuring moisture in walls remotely

There exist devices (e.g. Bosch PTD 1) which measure the temperature and humidity/moisture of the room and remotely (without contact) of a wall they are pointed at. I understand that you can measure ...
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1answer
162 views

Why are CO2 analyzers much more expensive that CO detectors?

This question emerges from Earth Science SE since recently there was asked this. There so far no one had the engineering/ measurement device expertise to answer this. I am aware that these are ...
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2answers
39 views

How to duplicate measurements from one piece of material to another?

I am not sure if this is the right place to ask this but. I have an offroad skateboard from MBS. I bought their brake system which comes with a circular piece of aluminum. Pictures attached. You can ...
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2answers
3k views

Darcy to SI permeation units

How can permeation units in Darcy be converted to the SI form. For example, how would 9.0 x 10-6 darcy be converted to SI units of permeation? How would it also be converted to the permeation units: (...
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1answer
68 views

What is the equivalent of ip rating for mechanical protection?

I'm very clumsy person so I like to buy tools that are just short of bomb proof. I want a pair of digital calipers. So I was wondering is there an equivalent of ip rating for being drop proof to say a ...
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1answer
45 views

Measuring vessel pressure scenario

I need someone to confirm or deny my understanding in the following situation. I have an empty vessel that is in equilibrium with the atmosphere and I have a pressure gauge on the vessel that ...
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2answers
499 views

How were 90 degree angles made?

It is easy to find a very flat surface, "perfect" straight edge, or squares for ensuring things are perpendicular. The machines that make these need to be flat/orthogonal to do so, but how were the ...
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2answers
115 views

Stretching material accurately with a machine

I am currently making software to interact with a conductive rubber cord. I am very interested in figuring out the percentage of a stretch of the cord, to determine how the resistance changes. ...
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2answers
3k views

How to get natural frequencies from accelerometer measurements?

I will be performing some tests and measuring the vibrations of a planetary gearbox. The accelerometer I will be using stays attached to the gearbox and saves the data into a log, which is available ...
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2answers
12k views

What is the "tl" unit of weight measurement?

I recently purchased a digital scale from eBay. According to the listing it can weigh in the following units: Multiple Weighting Units: g, oz, tl, ct. Screenshot of that page: Now I know that "g"...
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1answer
693 views

Multi Ratio Current Transformers

I encountered a problem in measuring electrical energy using a multi ratio current transformer (CT). The catalogue of CTs is unavailable. I have little information about the type of CT I am using. I ...
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1answer
35 views

Cutting silicon samples with plastic thin films

I'm measuring thicknesses of ~15 $\mu$m nickel thin films electroplated on a silicon substrate. I only have access to a SEM for this task. I need to cut the samples to get a side view of the film. ...
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0answers
52 views

Ambient helium level monitoring

I am looking for a solution to monitor and log ambient He levels down to 50-100ppm. The detector is meant to be installed in an experimental hall where a large number of Photo Multiplier Tubes are ...
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3answers
783 views

Is it Possible to Automatically Transform an Image of an Object into a Line Drawing in AutoCAD?

I have many photos of devices which must be traced into AutoCAD. Is there any software for tracing object edges/outlines automatically so that a Primary Plan of the object can be made in AutoCAD? For ...
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2answers
91 views

Units to use in this formula?

Should standard SI units be used in this formula or are other units supposed to be used for the formula for stress in a thin-walled spherical pressure vessel? $$\sigma_{yield}=\frac{P_g r_i}{2t}$$ ...
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0answers
70 views

Safety factor for pressurized container at 10 ATM

There is no secondary containment to hold any potential shrapnel. How would this change the safety factor that is standard at 2.5? The consequences of this container exploding would be quite extreme ...
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2answers
365 views

Measure stress of gas acting on a spherical container

How can I measure stress in a thin- walled sphere containing a gas? Is there a way to predict what the stress will be without actually needing to fill a sphere with gas? I am talking about hoop stress/...
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1answer
83 views

How to convert Square FT (in.) to Square FT (ft)? [closed]

I apologize for the confusing question title. I work with area rugs, and have almost never done measurements before. I am tasked with converting these measurements into the right unit. I have four ...
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1answer
313 views

How to measure calories actually burned from exercise?

I'm just an average person who questions the validity of my treadmill's claims about how many calories I've burned after an hour's worth of a cardio workout. How can I get a more accurate measurement ...