# Tag Info

44

For this answer, I'll be using this terrible excuse of a ruler, where ┃ is the lines indicating each millimeter and the . is just representing the left-most and right-most face of each of those lines 0 1 2 3 4 .┃. .┃. .┃. .┃. .┃. As I understand it, you're asking whether you should measure 1 mm as: 0 1 2 3 4 .┃. .┃...

28

You should include the thickness of one total line. In an ideal world, one would measure the the centre of each line (marked 'also correct' below). In this case, you're including half of each line. It's not always easy to judge the centre of the line on a rough plastic ruler, so, assuming that the lines are of equal width, it may be easier to measure from ...

5

In theory I agree with others, what's important here is consistency, exact values are meant to be at the center of the lines (so measure center to center or maybe easier from left side to left side). My emphasis here is on "meant to be": When you measure existing distance you are not supposed to read anything from that ruler more precise then a mm,...

4

The bicycle disk as shown is inherently prone to shimmying and spiraling into an increasing flutter. I have an Ebike with a very similar disk brake and I have learned my lesson to be cautious with it. As for controlled caliper force, one could use a scissor mechanism with a hook on the bottom which could be loaded by the desired weights as per the schematic ...

3

The basic thing you are looking at is a dynamometer - a generator mounted on trunnions to measure the reactive force. So, look at those then use a smaller motor as a generator - the ones I used were capable of controlling 100 to 150 kW - a bit large for what you describe.

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".

2

Neither, you should include the thickness of the line at your "zero" point and exclude the line at the termination of your end point.

2

Both 4-20mA and 0-10V (0-5V) are used in process control.  The 4 to 20 mA current loop is series, low impedance, long distance (>20m), noise resistant, two-wire, typically point-to-point, break or not connected detection (0mA), susceptible to increased series terminal resistance, and low rate of change sensors. The current loop can be multi-point, but in ...

2

I don't have a clear picture regarding HVAC, however I've used a lot of sensors both current and Voltage in many industrial and academic environments and projects. To my understanding current sensing is less susceptible to noise. I.e. you can transfer signal to greater distances without loss. Additionally, the 4-20mA has the added benefit that you can "...

2

With infinite budget, there are fantastic thermal micro-flow sensors, though they too have issues for drip-drip type situations. One thought, still same overall concept as the tipping bucket, could be to send the flow in a clear tube oriented vertically, with a normally-closed solenoid valve at the bottom. Have your automation optically detect (conceptual ...

2

The position of the calipers isn't what you are adjusting, it's the pressure you exert on them. Assuming the system is relatively slow (break force ramps up and down ~1 second), then a spring which is tensioned by a servo should work fine for this. If the spring is stretched further, the breaking force will be increased. Notice that even though the cable is ...

1

The standard method, as set out in the BIPM Guide to the Expression of Uncertainty in Measurement, is to work out the derivative of $y$ with respect to $x$ (in this case, $\mathsf{d}y/\mathsf{d}x = -1/x^2$), evaluate it at the modal value $x_{\star}$ of $x$ (i.e. at the peak of the probability density distribution over $x$), then estimate the standard ...

1

You could get 3 compression springs for your 1/2/3 levels of tip. Very high spring rate for #1, medium for #2 and low for #3, depending on what you need. The limit could be once you fully compress the spring (all the coils touch), that much force is how much should be needed to tip over whatever you're talking about.

1

Rain gauge tipping bucket data loggers are quite small. The whole thing is the size of a cookie tin. Bucket size (resolution) is about 1 cc. Decent explanation in the video below. https://www.youtube.com/watch?v=RruQhoXrVoE

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

No The only way to test a micrometer is with a gauge block or second mic.

1

Short answer: You need a load cell. There are many types available, but you will probably have to choose one of the more common ones because the special ones cost big bucks. Longer answer: You will need to mechanically constrain this whole assembly so that the load cell experiences force only on the correct axis; that won't be trivial to do. Alternate route: ...

1

I have worked with Autocad and ACAD3DS, but I know SketchUp has the same capability. In Autocad, you can import an image and scale it, then the program will turn it into a vector file that you can block and edit or add to your drawing. You can use a photo of the model you're interested in and turn it into a vector block. There are online apps that convert ...

1

As far as I can see- I think your error in measuring $\delta L$ should be zero. I mean apart from the increased friction, that might hinder the movement a bit, I don't think that you should get any error in the measurement of length.

1

Here is an image of a real life ruler. This is the magnification around 1 cm (on a thresholded image to show better a point). You can start to see that some lines are not always straight or full. That is what you'll get in real life (and it gets worse as you get older and you need prescription glasses :-) ). If you go further down you see, something like ...

1

If you're measuring weeks, you should choose a period that is exactly 168 hours long. You can measure from a particular time of a day, to the same time on the same day of the week (e.g. noon Sunday to noon the next Sunday). Measuring from the beginning of one day, to the end of that day of next week (e.g. the beginning of this Sunday until the end of next ...

1

You wrote that you know how microscopes work. Atomic Force Microscopes (AFM) can manipulate things. Tunneling microscopes can "see" atom level. Imagine a sharp needle with only one atom at its pointy part (if you cut a tungsten filament with scissors, you probably got one, so it's not impossible to make one). If you move a needle like that over a surface (...

1

For a less messy way to determine the volume of shaving cream use a three dimension scanner and software that can determine the volume of scanned items. Acquire some stainless steel, plastic or ceramic tiles. Weigh a tile. Place a dollop of cream on the tile. Weigh the tile with the cream & subtract the mass of the tile. Place the tile with cream in a ...

1

No.data: Value could not be sent via Bluetooth® Technology. Check the Bluetooth® connection on instrument and master device (on/off). Check if you are within the max. transmission range 5-15m. https://www.sylvac.ch/faq?view=topic&id=2 I have now resolved this issue in my case: the caliper's BT connection needs to be set up using the app that Sylvac has ...

1

This generator can seemingly make any fraction you want in unicode: https://qaz.wtf/u/fraction.cgi I put ¹⁄₁₆ in my Windows filename just fine. [Ironically enough, before finding the converter, I came up with using Shayne Turner's left bracket (1[16) idea.] As for indicating the inches measurement, I'm just using 2 single quotes instead of a double.

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