# Tag Info

8

It makes me wonder why some sort of counterweight system isn't used instead. I'd guess it's because residential garages are normally a bit limited on space and the counterweights need somewhere to go. Torsion springs are nice because they take up relatively little room on the ceiling of the garage, as opposed to counterweights, which would need space to ...

7

You could try a bath of concentrated acid. As long as you could maintain circulation so the concentration was fairly constant, a spring presents a very uniform cross-section and should be dissolved at a consistent rate. I would recommend keeping one of the springs as a reference so that you can measure the result after a short period and adjust your time ...

6

Assuming the spring is not fully compressed/bottomed out, it doesn't really matter if the spring material is expanding or not because it's a spring - it will deform to fill the space between the coils. Instead of providing an increasing distance, it will increase the force the spring exerts on your fulcrum. This shouldn't be an issue if you have the ...

6

Let's first compute the model. The control design is a separate effort. The torque applied to the drum is $n T_M$, where n is the gear ratio and $T_M$ is the output produced by the motor. $T_M= K_T i(t)$, where $K_T$ is a proportionality constant and $i(t)$ is the motor current. Now we can write the equations for the mechanical system:  m y''(t)+m g-k (...

5

Seems like to me the reason is a counterweight provides a constant offset to the door weight and that weight changes as the door is brought back to horizontal. I suppose there would be a way to design a variable counterweight mechanism but that would end up more complicated(costly) than the springs.

5

This is not an authoritative answer as I don't know the ATEX regulation that well. You have it however right that the ability to form a spark is relevant here. So your next step would be to look at the materials you use. Steel gives sparks on occassion. Most ATEX mechanical tools (hammers, wrenches) are from Bronze or Beryllium, so I would research in that ...

5

In the datasheets, this type of memory card socket is called "Push in, Push out", or simply "Push-Push". In contrast, the memory card socket that uses friction is called "Push in, Pull out". Keep in mind that these datasheets are geared towards electrical engineers and industrial designers, who are not necessarily interested in the workings of the moving ...

5

The mainsprings of mechanical timepieces provide an excellent example of how you can accomplish what you want. They are a type of torsion spring made from a metal ribbon which can typically be wound 6 or 7 full turns. The images below show what some of these look like when unwound and wound.

5

Both a torsion bar and a "coil" spring do what you want. The torsion bar is intended for rotation of only a fraction of a circle, and generally has a high spring constant. The coil spring can be designed for a number of rotations, generally with a lower spring constant. Look at any old windup watch or clock and most likely the energy storage mechanism is ...

5

There is a pervasive misconception that recoil can be "absorbed" by such things as springs and proprietary gas systems. This is not true; eventually all the recoil produced by launching the bullet must be absorbed by the shooter. The only thing that a spring/gas system can do is spread the recoil over a longer period of time, so that the force acting on ...

5

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. Furthermore, there is no physical mechanism active at room temperature and low applied stress in spring alloys that causes them to "season" or take a set on initial ...

5

N/m or Nm$^{-1}$ is the correct unit of a spring constant and it's already in SI units. Nm or N*m on the other hand is the unit of a torque (or moment) and is also in SI units. So no, Nm and Nm$^{-1}$ are not the same at all, they measure very different things. Similarly, Nsm$^{−1}$, Nsm and Nsm$^2$ are all different units of different dimensions to measure ...

4

I know your question is about springs, but I don't think that springs are the answer to your desired application. As you mentioned, the inward force from air pressure is very large so not only do you need a strong spring, but you also need a material for the paneling which is light and can take those kind of forces. Additionally, you would need to evacuate ...

4

I know of at least one case where such material was added inside the spring to dampen it. The spring will be resonant at some frequency. If there is enough component of that frequency in whatever is driving the spring, then it could oscillate or "ring". This can be undesirable because it will subject whatever it is connected to to forces at this frequency,...

4

The first design that comes to mind is a pneumatic cylinder with a large one-way valve and a slow two-way release on the back end. I've attached quick sketch below: The idea here is that the big valve on top can let air in freely - letting the device extend with little resistance. Pushing the piston back in, however, the large valve closes, forcing air out ...

4

Stretch in the spring delta $Y = A.sin(\omega.t) = A.sin\sqrt(k/m) . t$ So the delta Y is not constant but if you are interested in delt Y_max delta $Y max = m/k$, by Hooks law. Because your system doesn't accelerate except at the beginning and end assuming the pulley starts and stops suddenly that's you maximum. Any gradual start/stop acceleration ...

4

First off, the tensile strength is a property of the material, not the spring itself. Strength, often denoted as $\sigma = F/A$, can be considered how much force a material can withstand for a given cross-section. If you want something to be able to withstand more force the simplest approach is to increase the cross-section or get a stronger material. ...

4

The force which is needed to pull the pin out, will depend on the friction of the pin and the neighbouring material, and the surface at which the friction works. Let's assume a friction factor $\mu$ of 1, though it's probably less for plastics. That means that theoretically, just as much force is needed to remove the pin, as the force put on the pin by the ...

4

This has been asked and answered numerous times before: https://www.quora.com/Why-is-strain-energy-equal-to-1-2*force*displacement-What-about-the-remaining-half basically, it's because you're calculating the area under a triangle, because the strain energy increases linearly as the displacement increases. The Work term here refers to the final position, but ...

4

By "strength" do you mean stiffness/modulus? The modulus does not change with tensile or yield strengths. Make it with wire of 1/2 the diameter for 1/2 the modulus. Acid will hydrogen stress crack hardened steel ( This condition has many other names like "embrittlement".). Make it out of aluminum and get 1/3 the modulus or titanium and get 2/3 the modulus ( ...

3

I think two equal springs would test very close to a spring with double the spring constant. See adding springs in parallel equation. Two springs may be somewhat less material efficient than a single spring; because the cross section of a spring wire has an area moment of inertial (just like a beam) that provides the restoring force and the equation is not ...

3

I’ll be installing a custom counterweight for my new garage door – it requires some clever engineering to make it work since a residential garage door doesn’t have a fixed weight: its track bends right above the door opening, and the part that is in the horizontal raceway provides no vertical load to the counterweight. So, as the door opens, it gets lighter ...

3

Door closer is a great mechanism - at it's heart is a dashpot - and a check valve. If you have a check valve in parallel to the dashpot, that accomplishes the desired function. Watch below: This is your mechanism at rest. You could add a spring to the top of the dashpot to force it to go back to the fully closed state when finished - but that would ...

3

Your question is insufficiently constrained. The short answer is that you haven't provided enough information to give a complete answer: creep is complicated enough for a single material, however there are a variety of mechanisms depending on the material, temperature, normalised stress, time etc etc. In a "generic metal" the below diagram is a ...

3

Spring rate can be specified either for a whole spring or per unit length which is often more convenient if you are buying spring stock to cut to length. The constant of a whole spring is force per unit length of extension the rate constant will be F/L/L so force. This isn't particularly physically meaningful but is convenient if you are buying spring ...

3

There are different designs of springs, with different properties: Constant Force Springs - Constant Force Spring Design Theory (2nd Source) The extension type of constant force spring represents the most basic, yet most versatile, type of constant force spring. It is a pre-stressed flat strip of spring material which is formed into virtually constant ...

3

You can buy endoscope or borescope cables which should "just work," though 20m is longer than the typical cable you will find on Amazon or Ebay. If you want to try making your own, look at the design of Bowden cables (used for brake cables on bikes, etc). The outer cover is made like a coil spring, so it can bend around a large radius but won't "buckle" ...

3

Most electrical engineers use an electrician Conduit Ducting wire for that (which you could use in your cable setup), but in your case it probably easier to use a piece of string and a vacuum cleaner. Put the vacuum cleaner at one end and suck the piece of string through. Then pull the camera through using the string like explained in How to get cables in a ...

3

Probably just another hypotetical idea: If you squeeze the wire from circular into a square shape, it will have about 54% of the original rate. If you squeeze it slightly more into a rectangle, it will at some point become 50%. And 1/2 the diameter of the wire does not gie you 1/2 the rate. It would give you 1/16 of the rate. 85% of the diameter gives you ...

3

Another hypothetical way to reduce the amount of material in the spring would be to fix it in a jig stretched to double its normal length. Then, heat it sufficiently to anneal it and remove the tension in it. Then, re-temper it and cut it in half, back to its original length. But just buying a new spring would be a much simpler method.

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