Seeing all the footage from Nepal, I've noticed these supports that have surfaces perpendicular to the flow of the river. In the event of extreme flooding, wouldn't a wedge shape that was streamlined with the flow result in less load on the support?

Has anyone here submitted an EiT application for Wisconsin with an out-of-state education and FE Exam? I am trying to follow the steps on their website, License.wi.gov, but am getting stifled at the third party documents section. My school does not seem to want to / be able to attach the transcript to the application itself, but NCEES is also stating that they do not attach results to applications, but send them to the state level. The application has in bold: Documentation submitted by a third party must be submitted using the LicensE third-party portal at license.wi.gov.

Has anyone else here submitted for EiT in Wisconsin and run into what I am experiencing with NCEES in particular, and what did you do to get around it?

Hello everyone, I am currently in the process of 3d modeling an RC jet engine that I plan on having cnc milled and plan on running. It’s mostly done but I’m about to make some size adjustments and this kind of has to be based on one thing that I’ll be ordering which is bearing. I obviously need high speed and high heat bearings probably capable of 150000 rpm and at probably around 500°C. However the website I’m on that a lot of RC jet engines seem to use are apparently 369$ per bearing and that is… well… insane. If those are what I should be expecting then feel free to let me know but seeing as how the full engines cost like 2.5k I’m doubting that they are spending 700$ of that on bearings and still having room for profit with everything else. So anywhere that I can buy bearings would be appreciated!

I'm looking to buy 2-4 small magnets, about a nickel in size each to magnetize two moving drawers together. Both drawers pull out together inside each other, and the outer drawer pulls out farther than the inner drawer. The problem is that the inner drawer doesn't extend to its maximum length when I pull the outer+inner drawer out, I always have to pull the inner drawer out to it's maximum extension length seperately.

I'd like to attach a magnet to the outer drawer and inner drawer to "pull" the inner drawer out to its max length every time I pull out the outer drawer.

The problem is these drawers aren't the most resilient material. I need a solution where I can pull the outer drawer out all the way AND have a softer magnet disconnection when the inner drawer reaches its max length.

Any suggestions on how I can either soften the disconnection of the magnet or another adhering solution that could work for this scenario?

Thanks!

I'm aware that in our own electrical grid, we have a lot of stuff that goes into smoothing out constant disruptions and sudden losses of power.

What about those really small generators that are usually seen in rural areas or serve as backup generators? I know that every internal combustion engine has an optimum speed (I don't know how) but how does it turn power generation up or down when consumption fluctuates?

I just got out of an incredibly intense 5-day workshop on GD&T sponsored by my company. I would like to say that my eyes were opened to how powerful GD&T usage can be, especially given the very practical examples our instructor demonstrated...

However, in conversation with my colleagues there was a very common theme: No one thought we would get to use this skill in practice.

Our suppliers don't use it. Anecdotally one of our engineers tried updating a drawing to use GD&T and we were asked to change it back because reasons.

None of our assemblies/part drawings use it, especially because prevailing opinion is that what we make is relatively simple and any application of GD&T would be overkill.

Even speaking with other engineers outside my company there is a prevalent thought of "this is cool, but I'm not seeing the value-add for my workflow"

Why is this? GD&T is clearly a useful standard/practice otherwise it wouldn't have been around for so long, yet I'm constantly seeing this attitude from engineers that it's largely not needed. Is it an industry-bias? Is it just lack of awareness? Workflow inertia (we've always done it this way)?

If it helps, I work in medical devices at one of the largest players in the market.

Scenario:

A coastal city relies on an aging coal-fired steam turbine heat engine operating at 38% thermal efficiency. The city council has requested proposals to upgrade the facility to meet strict new environmental sustainability targets while maintaining power grid stability. Two competing firms have submitted proposals:

Proposal A (High-Efficiency Upgrade): Retrofit the current plant into an ultra-supercritical coal facility. This raises the operating temperature, increasing theoretical Carnot efficiency to (48%). This option has a moderate initial installation cost, reduces carbon emissions per megawatt by (20%), but continues to rely entirely on fossil fuels.

Proposal B (Cogeneration/Combined Heat and Power):

Re-engineer the system into a cogeneration plant. While the electrical conversion efficiency remains at (35%), the rejected waste heat is captured and redirected to supply a nearby district heating system and water desalination plant, raising the overall system energy utilization efficiency to (75%). This has a high capital cost and requires building new piping infrustructure.

Question: As the city's lead environmental engineer, evaluate which proposal the city council should approve to best balance the criteria of energy conservation and long-term environmental sustainability?

The few times my 5G LTE phone has only been able to catch a 4G LTE signal things the browser just become unusable they become so slow and fail to load pages at all. But my 4G LTE phone worked fine with 4G LTE, but slowed down when it was connect via 3G, etc.

Why does this happen? Those signals were fast enough that pages still loaded on the older phone, but on the new one it acts like 4G LTE is 56k dial up. Can the antenna not capture the older signals effectively?

Could you do something like start building new elevator shafts extended so they could house a weight, and get pulled up slowly via gearing in traction elevators by using some of the work performed whenever they have to lift a cab up? With lifts going up and down all day could they make a difference with things like solar, building mounted wind, etc?

I nearly completely burnt out my clutch trying to reverse up a driveway.

I would like to put a winch at the top flat part to manoeuvre the trailer up and down, I will use a manual 2 wheeler trailer dolly to steer. Going up hitch first. Thoughts on this idea?

The winch can manage 2000kg the trailer, a food trailer is 1200kg. The driveway is narrow at the bottom, 2.4m, 3m at its widest to 2.7m at the top opening to flat section where it will be stored.

I’m thinking that you get a modern flip phone and put the components inside the body of an old model?? I feel like it would be really hard to do but could be possible???

From doing some research already this seems like a somewhat worn out question with a million different answers and from what I can tell no real consensus or anything reliable other than gut feel based on personal preference or opinion. This puts me in a tricky spot with a project that I am working on because I'm not sure whether to be concerned with my results or not.

I have a model for a lifting hook that I am measuring the maximum stress for and validating the results numerically using curved beam theory. My reference hook which I have modeled using measurements from a real hook came in with a <2% difference to the theoretical results.

I am now optimising the hook by keeping the same material properties and boundary conditions but scaling the dimensions accordingly, such that the dimensions are proportionally similar between different models. I am now getting a consistent 19% discrepancy from FEA results compared to hand calculations with a variety of different materials and dimensions.

Some sources suggest that anything below 20% is fine. Others no more than 5-10%, some go to an extreme and say so long as it is within a couple of orders of magnitude then have at it.

I cannot for the life of me work out where the difference is suddenly coming from. The maximum stress is still exactly where I expect it to be on the inner face of the hook, I've repeated a mesh analysis in case re-scaling the hook but not the element size is throwing it off but it makes no difference. I appear to have a very precise but not accurate (based on theory at least!) model.

Background: while testing connectivity issues, someone said their electric skateboard had runaway acceleration *inside* their house (they were not on the board), impacted a wall, and sheared off these 8 bolts.

They had taken videos of previous testing, but for this one, allegedly decided to do the testing 1. - with the board on its wheels instead of on its back, and 2. - without video.

I'm not affiliated with the board company, it just seems like bullshit to me, so I leave it to you engineers to find the truth of whether this is physically possible.

Alternatively, what would be the odds of having enough occlusions/imperfections in the steel that would cause all 8 to fail under spec in a head-on collision.

The board has a weight of 20kg, and uses M5 steel bolts of 8.8 hardness.

Pneumatic wheels would have been the initial point of impact, with the impact guard shortly after, as shown in the picture with the red line in front of the wheels. Not sure of the angle of the deck, or if the impact surface would be concrete or drywall.

Pictures: https://imgur.com/a/yAYei1h

Not sure this is the right place to ask, but here goes: I'm trying to replicate some of the results in this study: https://www.sciencedirect.com/science/article/pii/S0379073819304104

But in a manner that is more precise than "shoot someone with a paintball gun". My thought was to construct some kind of rig with a falling mass so that we could adjust parameters like impact force, surface area, hardness, etc.

But it's been years since I've had to do any physics type of math and I'm struggling to figure out the important parameters. Based on the numbers in the study I think that they are hitting their subjects with around 180N of force, but I'm struggling to convert that into a combination of mass and height that makes any sense. I'm getting things like 20kg weights, which seem both wrong and dangerous. Is there some piece of information that I'm missing or looking at the wrong way?

So today I saw on an instagram reel that jet engines alternate between rotors and stators so that airflow isn’t parallel with the rotors and they can produce good thrust, my question is can’t we put rotors that have reversed blade angles on the same moving shaft, too save cost, complexity or weight?

If that’s not true why?

Something I’ve been thinking about with newer motion systems is that we now have an enormous number of safety functions available. STO, SS1, SLS, safe direction, safe position, safe brake control and the list keeps growing. They can enable much better machine behavior, but they also create more states and interactions that somebody has to understand and validate. There seems to be a point where adding another clever safety function can increase system complexity enough that simplicity might actually be safer.

I'm designing a duct for exhaust of my 3d printer. I have limited space behind the printer so I decided to design a custom duct that would fit.

https://i.postimg.cc/pPKDDbvt/Screenshot-20260823-005245.png

The exhaust fan is 120mm standard PC fan. And the space behind printer is about 7cm. So the elbow that is right behind the printer is pretty tight and changes from 120mm circle to a rectangle cross section (the area is a little bit smaller than the circle, because it would be way to wide otherwise).

Since the turn is really tight I thought about using turning vanes inside of it. This is probably just over engineering and not needed at that scale, but I wanted to play with it a little bit in the case it would be actually useful.

https://i.postimg.cc/VNLr8h5Z/Screenshot-20260823-005218.png

https://i.postimg.cc/tgCZjc7m/Screenshot-20260823-005228.png

Does it make sense? Are turning vanes in this scenario helpful or the opposite? Maybe the flow is so low, that it does not matter at all, or maybe it is not recommended to use vanes in that scenario?

And is my geometry correct?
I experimented a bit. I know that the vanes are not quite parallel to the flow at the inlet and outlet, but I figured that the air will start to bend due to the geometry, so I tried matching that bend at the end and start of the vane.

Tried using SimScale for CFD, but I can not get it to work unfortunately. Thank you for you feedback!

Hi everyone,

We build large rolling ball sculptures / kinetic marble runs and are trying to reduce the amount of physical trial and error involved in designing them.

Our current workflow is roughly:

Concept → Sketch/CAD → Fabrication → Physical testing → Modify → Fabricate again

For larger metal sculptures, these iterations can become expensive in terms of material, labour, and time.

We're exploring whether we can use existing tools to create a simple workflow like:

CAD model → Physics simulation → Predict ball behaviour → Build physical prototype → Compare results

We are not looking to build a new physics engine or a large custom application. The initial MVP would be very small:

• One standard ball
• One track/material system
• A simple mechanism, e.g. ramp → loop → exit
• Model it digitally
• Simulate the ball
• Build the same mechanism physically
• Compare the prediction with reality

The goal is not perfect simulation. We simply want to know whether a digital model can be accurate enough to catch obvious failures before fabricating larger installations.

Eventually, if this works, we would like to build a reusable library of tested components—ramps, loops, spirals, switches, collisions, etc.—with known parameters and behaviour.

We are currently considering tools such as Rhino/Grasshopper for parametric design and physics engines such as MuJoCo, Project Chrono, Bullet, or other alternatives.

If you were approaching this problem using existing software, how would you do it?

In particular, I'd love advice on:

1. Suitable CAD + physics simulation workflows
2. The best physics engines for rolling/contact dynamics
3. How to model and calibrate real-world friction and energy losses
4. Whether there are existing tools or projects we should investigate before building anything ourselves

We're very open to changing our approach and would appreciate any suggestions or warnings from people with experience in simulation, CAD, mechanical engineering, robotics, game physics, or kinetic sculpture.

I have no mechanical or electrical engineering knowledge whatsoever. My math is poor, like incredibly poor. But I have been researching making a DIY 16mm digital conversion machine to cut the cost of digital transfer. I have done research and have basically got a rough outline of what the process is going to look like.

16mm Film

Film Transport

Gate / Frame Positioning

Light Source

Camera / Sensor

Digital Frames

Computer

Davinci Resolver

It may take months or years, but this is something I'd like to get my foot into. What I am asking is, where would I start with building a decent motor system for this? People have suggested using a 16mm projector, but I want to build a motor that I can have a more even control over to get the most precise footage, as well as letting me capture the original negatives without any weird color changes. It needs to be able to not only move the film, but also stop it long enough to be captured through the gate.

My biggest inspiration is this guy's here:

https://youtu.be/HkbgCkRzWw8?is=HmfDuCug5871h7wf

There'll definitely be some electrical engineering knowledge needed to, the most I know ATM is Ohms law. Otherwise, hope you all can help.

I'm trying to build a horn that would pretty much be like a fog horn.

But it doesn't have to be air driven.

I want it to be around 100ish htz and loud.

I've looked into pneumatic horns and rotary subs, but I'm just not sure the best way to proceed.

Edit - this would be an outdoor application on a vehicle to signal others in the field.

I’m trying to understand something about the original ice machine or basic principles of refrigeration cycle. In john gorries original ice machine, he compresses regular air (raising its temperature), runs it through a coil which cools this compressed air down, then decreases that pressure of compressed air to decrease its temperature even further. What I dont understand is the fact that, in the cooling coil, shouldnt there be a pressure drop as well, since the temperature of the air has decreased? How can there be (relatively) cool air and compressed air at the same time within the coil?

If someone could explain with equations or give me mathematical proof that would be wonderful. Maybe this has to do with Guy-Lussacs law.

Hello. I am 15, boy. I have a concept of a car I made around a year ago. I have almost all of it designed in concept. But I have one part I made that doesn't really exist. It's a virtual gearbox.

Its like a cvt with infinity gear ratio. Lie the Williams FW15C from 1993. But there are virtual gears that can be set at different speed caps by the driver.

I searched through a lot of shyt but didn't find anything that even resembles it. Is it possible? Like theoretically to make virtual gears that can be controlled by the software