niels nielsen
  • Member for 4 years, 3 months
  • Last seen this week
  • corvallis, oregon, united states
How did mechanical engineers work before SolidWorks?
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42 votes

At the beginning of my career (1979) as a design engineer at HP, the mechanical engineer created the part design and then rendered it in pencil on paper, and then transferred it onto sheets of vellum ...

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Why doesn't epoxy stick to silicone?
27 votes

There are two reasons why. First, for any glue to stick to something, that something needs to be wettable by the glue. A cured silicone surface is bristling with uncrosslinked silicone units which ...

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Why exactly does a washer help distribute the stress around a bolt?
16 votes

Except for special applications, most washers are made of dead soft steel, which deforms under the compressive load imposed by a tightened bolt head. As the washer smooshes, it minimizes stress ...

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Can aluminium foil be a thermal insulator?
15 votes

If furnished in a thin, polished sheet, aluminum will reflect infrared radiation, as for instance in a so-called "space blanket" which consists of a thin sheet of plastic on which a thin and ...

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How does a helicopter hover
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15 votes

Most helicopters of modern manufacture are dynamically unstable while hovering- they require constant, "hands-on" control inputs from the pilot to keep things in balance. This task is very ...

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What is the physical meaning of pulse rate and blood pressure, from a turbo machinery point of view?
12 votes

high pulse rate + low pressure means low pumping efficiency of the heart. this can be caused by: leaking valves, especially the main aortic valve, due to disease or calcification; low blood volume, ...

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Why are most jigsaw blades designed to cut on the up stroke and have teeth that point towards the shank?
11 votes

To enlarge slightly upon Solar Mike's response, a jigsaw that cuts on the upstroke tends to yank the saw shoe down into firm contact with the workpiece. This guarantees that the cut angle will match ...

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This device is used in washing machines to dispense water and cleaning solution in the right amounts. What is the working principal of it?
11 votes

To add just a little to the answer from Mahendra Gunawardena, that device contains an electromagnetic coil and nearby a piece of iron that is connected to a valve mechanism. When electricity is sent ...

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Does a motor suffer damage when resistance to the intended motion is met?
10 votes

The answer depends on the specific type of motor you intend to use, but in general: when a motor is loaded down, it draws more current, which means its windings get hotter at the same time that the ...

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How to fix this gear
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10 votes

Oddly enough, this problem can be fixed using a set of car keys and your wallet. Here are the steps to follow: 1) put the keys in the ignition of your car, start it, and drive to the motorcycle ...

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Why don't towers use buoyancy to reduce weight?
9 votes

The engineering design of towers is not limited in a practical sense by their weight, meaning that the scheme you propose solves no problems in that field. Truly gigantic balloons would be necessary ...

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How is it possible that "fiddling around with" batteries can apparently give them more power?
7 votes

It is common for both the button contacts on the ends of a battery and the springy metal fingers that make contact with those buttons to get a thin film of oxide forming on them. It does not take much ...

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How do I start looking for a cheap encoder?
7 votes

In the past whenever I needed a rotary encoder, I took apart a computer mouse. I do not know if they will meet your requirements, but there's nothing cheaper.

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Ways to brake an axle
6 votes

In the wire & cable business, the device you describe is called a dancer, for the way its components move about while regulating the tension in a rope or wire being unspooled from a large coil. ...

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How/why lubricating a rolling bearing would make them spin less time (dissipate energy faster)?
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6 votes

The lubricant you put into the spinner bearings has both viscosity and surface tension, and it coats the rotating parts inside the bearing. Therefore, as the spinner bearing revolves, it churns the ...

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Should Engineers Understand Equations without Relying on Derivations?
6 votes

Knowing the derivation is important because it usually tells you what initial assumptions were made in the derivation and what the limits of applicability of the resulting equation are. Understanding ...

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Purpose and name of fine pitch marks on a cast metal part
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6 votes

these are part-tracking marks. they indicate which cavity in the mold the part was cast from, in which mold set, in what molding machine, in what year, month, day and shift. this way, a part that ...

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Is there any speed difference if we replace a 200-300 meters of copper cables with optical fiber cables? Whats the reason if it increases?
5 votes

Fiber cables have higher data transfer speed not because light travels faster in a fiber than electromagnetic waves in a copper wire, but because they can be modulated by signals having far higher ...

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What is a "mill-hardened" material?
5 votes

Mill hardening would refer to work hardening, where cold-rolling the material distorts the grain structure and causes dislocation pile-up and entanglements, which reduce the material's ductility and ...

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Furnace Combustion Air Properties
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5 votes

the outside air is colder, but the flame temperature is still much much hotter than that so the difference cold inlet air makes on the outlet temperature of the furnace will be small. The same ...

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How is a highway prevented from being buried by sand in the desert?
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5 votes

The usual solution is to build a fence with lots of slats in it about 20 feet away from the edge of the road. The fence slows down the airflow and thereby causes the sand in it to fall out and ...

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Why is the thread of the screw linear? Can it be wavy?
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5 votes

This idea doesn't work, because screwing the parts together will tend to strip the threads before the parts are fully squeezed together. Instead, engineers use different general methods to get the ...

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Do generators produce a fixed load?
5 votes

As you add bulbs in parallel, the load impedance drops and to light all the bulbs you have to pedal harder. When the load impedance becomes less than the output impedance of the generator, then more ...

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Why did the Soviet Alfa-class submarines have a titanium hull?
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5 votes

the former soviet union had plentiful stores of titanium on hand, so its expense was not an issue. Being nonmagnetic, a titanium hull would be more difficult to detect with magnetometers. Note ...

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Spring degradation in hand grip trainer
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5 votes

for a properly-designed (right materials, right size, right manufacture) spring of that type, the applied stresses are far too small to cause any plastic deformation (permanent bending) at all. ...

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Why did steam locomotives not transfer power by cogwheels?
5 votes

for a while, steam locomotives actually used gears and cylinder/piston sets which drove crankshafts. These were called geared locomotives and they were used to haul heavy loads up particularly steep ...

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Why lead was chosen as the metal for lead-acid batteries?
5 votes

each electrochemical reaction involving a lead atom in a lead-acid cell releases two electrons into the external circuit, which means it has a relatively good extractable power-to battery mass ratio. ...

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Why do drag race semi trucks slant to one side?
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5 votes

as the engine produces torque which is applied to the driveshaft, the engine block produces a counter-torque which must be blocked by bolting the block to the frame so the engine itself does not ...

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Damage to drill through torque?
Accepted answer
4 votes

The very first thing to check is the sharpness of the bit tip. a dull bit will not drill worth a d*mn and just waste your battery power. Note that it only takes one brief encounter with something hard ...

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Why no big and slow flywheels for utility-scale energy storage?
4 votes

What you are missing is that it is cheaper to increase the storage capacity of a flywheel by increasing its rotating speed than it is by making the flywheel bigger. This is the reason why (proposed) ...

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