Quick background, at my spring review, my boss made one of my goals this year to learn a bit more about PLC and PLC programming, as our Automation Engineer is getting overwhelmed, and could use some help. It made a lot of sense as I have some Electrical Engineering background, but not much with PLCs. I spoke with our AE, and discussed some things I could do to get the ball rolling on this, and he suggested purchasing a couple cheap PLCs from Automation Direct to play with and build a few practice projects such as the standard stoplight controls. It was then that it hit me that I was in the process of building a 560 gallon rain forest vivarium, and I could this as my project to learn on. The AE agreed that this would be a great project to get started on, and it has been. I've learned a lot about sensors, controls, setting up an HMI, predictions vs realities, design of a electrical panel, and adjustments to the plan when unexpected issues arise. However, I'm having some issues with the humidity controls, and could use some assistance.

My first issue is a reliable humidity sensor that doesn't drift downwards over time at continuous high humidity. I've used a number of cheap sensors over the years, and I've noticed a trend that over time they become less reliable to the point the sensor tells me that the picture below is 45% RH. (30 minutes like this)

https://preview.redd.it/741n9gs28b4e1.jpg?width=2448&format=pjpg&auto=webp&s=e16a849afd8423eee475827bb9bbcf75b709a982

I'm currently using cheap STC-3028 24v humidity controllers, so I'm not shocked they stopped working after only 2 months of active use. I chose them as they were panel mount, and could be wired in to the PLC using a simple On/Off call for humidity and use the controller to set the humidity parameters and the PLC to satisfy that call depending on time of day, temperature, etc.

I'm looking for recommendations for similar controllers if possible, but if not, a reliable sensor that can handle long term high humidity. I also have 1: 4-20ma input, 1: 0-10vdc input available as well, in case I need to wire a sensor directly to the PLC.

Important note, the water in the system recycles constantly, and the fog generator/rain pump use this recycled water. The overall system is fairly low nutrient, but the water will pick up minerals and nutrients as it cycle through the tank. I do believe this is a major part of the rapid failure of the cheap sensors. Also, as this is a entirely self funded project, and my funds aren't unlimited. I don't have the extra cash to purchase the $1000 sensors I've seen while trying to figure this out, but have no problem spending $100 for something that works but don't want to spend that kind of money for a sensor to have it fail as well.

My second issue is that the relay that drives the fogger keeps getting stuck in the on position. I'm using a 200w 6 head ultrasonic transducer to generate the fog. This should be drawing no more than 2.5 amps of power with the fan that drives the fog. Initially I had it wired to the PLC 3amp 110vac output, but it would stick on frequently. I assumed maybe I was running too close to the amp limit, and that the internal relay was just not releasing when the coil was denergized, so I purchased a external 6 amp solid state relay and rewired to it. Today it stuck on again. I confirmed that the PLC had shut the output off (via the computer), and looked at the PLC and confirmed it was off, and looked at the relay that has a LED to indicate the coil was energized. All off, yet the fogger was still powered. I popped the relay out of it's nest, and it clicked off. Reinstalled the relay, and it remained off. Manually turning the output on/off from the HMI and it worked fine once again. My theory at the moment is that the initial surge of the relay turning on is what is causing this, and that a capacitor across the relay legs should reduce that initial spike of energy, but was wondering if anyone had a better solution.

Inflammatory title aside, I‘m in my first year studying ME, reading posts in this sub makes me doubt that decision a bit..

I find ME incredibly interesting, I wouldn’t have gone for it if I didn’t, that being said - is the job market actually as bad as people here say it is? Are salaries really that low? Is the work not rewarding?

I think I‘m looking for a bit of reassurance/ inspiration as I head back to the dorms for another week of Algebra and Calc.

I am interviewing for an EIT position at a small consulting company. This would be my first job after graduation but I have almost 2 years of co-op experience. I have only worked for companies with around 100 employees and I am really not sure what to expect at a smaller company. Are there any red flags I should watch out for being a smaller company? As far as I can tell all of the current employees + owner (4 people) are going to be interviewing me so I imagine it's important that we get along on a personal level, but I don't want to get too comfortable and be unprofessional.

I am also curious if anyone has insight regarding pay expectations vs a larger company. Part of me thinks they might low-ball due to smaller revenue but I suppose having less pieces of the pie to cut could be beneficial depending on company leadership.

Aside from this, if anyone has any tips regarding technical/other questions I can expect from a small organization like this, or any helpful advice at all it would be very much appreciated. I am so nervous and very in need of this job and I cannot mess it up, anything you can share to help me prepare would be a lifesaver.

Thank you!

Title^

I’m currently working on a lab report and I’ve come across the point that when pumps are arranged in series, they should ideally have the same flow rate, although they can have different heads. For example, if you have two identical pumps—one running at 1500 RPM and the other at 2000 RPM—used in series, is this configuration advisable, or could it cause issues

Using a standard even number gear ratios for gears, and using sheet metal, how would using a battery and a piece of rock from the earth allow solid time movement for a Casio watch, I know the battery has like electrons and stuff with like the gravitational pull with like a function able compass, but how and why does the battery not stop the hands from stopping. Or basically why does a hand wound watch last so little time compared to a 10 year battery on a regular quartz watch, so basically why does quartz keep good time and like idek bismuth not keep , plus why does the Rolex watched for going into the Mariana Trench and up at Mt Everest get tested and how do you know it’ll really pass those nature tests, and why do most companies fuck around with their statistics cause every time I test technology it’s always has a 10%+/- margin of error despite being all new

TLDR how does a super monkeys laser eyes or the laser guns in sci fi work irl

Hello everyone,

I’m reaching out to ask for your advice on securing a job as a Mechanical Engineer in the UK. I’m a 26-year-old Italian with a Master’s degree in Mechanical Engineering, currently pursuing further specialization in Machine Learning and Big Data. My interest in this career move isn’t just professional—it’s also personal, as my girlfriend is Scottish, and I feel it’s time to start building our future together.

I’m particularly interested in joining big aerospace companies like Airbus, Rolls-Royce, or GE. My questions are:

Do these companies hire foreign candidates, and what can I do to stand out?

Would focusing on networking, gaining additional skills, or something else make me a top candidate?

Currently, I work for a major company in the railway sector, but I’m not satisfied with my job. Transitioning into aerospace feels like a better fit for my aspirations. I’d greatly appreciate any insights, suggestions, or personal experiences you might have to share.

Thanks in advance for your help!

Hi,

I am doing a project on solar desalination reverse osmosis and it uses a reverse osmosis memebrane to filter salt water but water doesnt seem to come outside. How do I fix this ?

Attached is the image of the revserse osmosis membrane.

Thanks

25M. Exp: 3 yrs. Working in an American company as a PID Designer. Jobs good and future looks good to in 4-5 years, but salary is not that great as compared to friends working in IT.

Currently working remotely from India from home so no major expenses but I feel being left out and lacking behind.

Wondering if doing a masters is a good option or should I continue with the job. My academics was average, first job was in oil & gas industry… current job is in a product based company.

Hello i am a freshman ME student from the Philippines and i am looking for fellow students who are 3rd,4th years and irregulars to answer questions prepared by my team for an activity. Don't worry, their are only 5 questions, and just identification we just an ID. I'm sorry I don't have anything to give in return, the students from my school and others nearby are not giving us opportunities, and we are just desperate. Please let me know down bellow if you're interested

1. Q6 >Q4>Q5
2. Q4>Q6>Q5

When I calculate the related equations, most of the solutions suggest that the flow rate through Pipe 5 is very low. Is this result reasonable? There are T & 90-degree joints and frictions.

I got an offer to intern at NSWC Crane, and was wondering if working there would give me a significant benefit when applying to private defense contractors like Raytheon and Lockheed Martin.

I know that NSWC will help me get my security clearance, but how valuable is that really, and will that make a difference when applying for internships at these private places?

Hello,

I have an issue. I work in a secure environment. A badge must be used to enter, and a cell phone is strictly prohibited.

But with a family pet death and bunch of personal issues, I am so stressed out and distracted that I accidentally brought my phone in twice in one month and I have been given the last infraction warning.

I’ve been told to be a functioning adult and remember things. But with multiple personal and medical worries, i do not trust myself anymore to remember self pat downs. And i don’t want to be fired. The actual work performance is superb because it doesn’t require me to remember things.

I am trying to either make or repurpose an existing device that will do this: much pefer to just buy something that exists and modify.

• badge is always in the contraption in the car console
• i must insert my phone (or an object like it) to release the badge. It isn’t simple to remove without inserting phone.
• If I forget to leave the phone in car, then I do not have the badge to enter. And forces me to go back to the car to insert phone and retrieve badge.

The Image shows my failed attempt. I made a contraption like the image but the fabric (red line), causes much friction and gets stuck.

Please. If you know of any device or way to make it… please help. It can use magnets attached to phone, pressure, weight, anything as long as I can eaily make it or buy something and modify it. It needs to fit into the center console of the car.

I'm in talks for a job that would require me to get security clearance. Probably top secret. What are the downsides to obtaining security clearance? After talking to some friends it seems like there's extra paperwork if you travel internationally. What else becomes harder to do with clearance?

Hello, I hope this kind of question is welcome here.

I'm trying to build a train wheel mechanism (one wheel driving a second wheel using a coupling rod) for a project. I've been working on prototypes, but cannot get it to behave the way it should. I've attached images showing the prototype.

The issue is that I cannot get the wheels to turn together. I have researched this as best I could, including terms such as "train wheel mechanism", "double crank train wheel mechanism", "inversion four bar kinematic chain [1]", etc. I have found a lot of theory [2], and some videos [3] showing the finished product, but no explicit instructions on how to actually build one. I've watched many videos of trains[4] for insight, but nothing I have tried has worked.

The prototype works when the first wheel is turned up to ~70 deg, but then the secondary wheel reverses direction. I think I understand why it is doing what it is doing, but I don't know how to make it work the way I expect.

Both wheels are free to spin about a vertical axis. Each wheel has a fixed vertical "bar" (screw). The coupling rod slips onto each of these vertical bars, one on each end. A slight turn on one wheel turns the other wheel in tandem, but near a quarter turn, the second wheel changes direction.

Some sources mention a crank, which I believe (but I may be wrong) in my prototype is the wheel plus the fixed vertical "bar".

At this point, there are several things I think might be problem, but I am largely guessing:

- Maybe I'm missing some fundamental part of the mechanism
- Maybe the coupling rod is too long
- Maybe I'm misunderstanding the crank concept
- Maybe the coarse nature of the prototype is to blame

What's interesting is that, near the 90-deg mark, there's some resistance in the turns. I tried slotting the coupling rod, but that didn't improve anything.

Overview

Overview, Angled

Overview, Front

Assembled

Initial (minor) rotation

Does anyone have any thoughts, ideas, advice, or resources on this?

Continued (major) rotation

I'm taking the Fundamentals of Engineering exam next week, and I'm feeling more than a little underprepared. Like I didn't study hard enough when I had the chance, and because of that I'm not going to do well enough on it. Those of you with experience with the exam, is there anything you think I should know?

Making a pulley system to lift up to a 50kg object but just getting my head around the numbers. This is just a single pulley system for changing rope direction, not doubled or more for any mechanical advantage.

There will be the object, rope goes vertically straight up to a pulley, turns 90 degrees and runs horizontally to a second pulley then turns 90 degrees to run vertically back down.

Assuming friction is negligible, am I correct in thinking that each 90 degree turn adds about 40% more weight to lift the object (weight to pull the rope), or is it just 40% more weight on the pulley support but still the object weight to pull on the rope.

So the force needed to lift 50kg would be approx:

A) 50kg x 1.4 x 1.4 = 98kg or;

B) still just 50kg

Hello, I am a recent grad in mechanical engineering from a top school in Canada. During my undergrad, I had four internships with a well-known tech company based in the US. I received positive feedback from the managers I had in various teams, however I did not receive any full-time offers. These internships were mainly in mechanical design, which at the time I did not feel super passionate about as it involved long hours staring at CAD models with little hands-on work. Everything I worked on was under NDA and so unfortunately I was unable to build a portfolio from any of the projects I worked on here.

I am currently working at a mid-sized engineering consulting firm and the work is very boring to me. It is a very old-school company that is focused more on client work rather than actual engineering and innovation. I applied to hundreds of jobs in my final year of school, and after very few interviews this was the only offer I received. Despite knowing this was not the type of work I wanted to do, I accepted the job out of fear of not finding anything else.

I would really like to level up my engineering career but I am unsure what to do. I would like to work in an industry that is rapidly growing and can provide the opportunity to contribute meaningfully to the world. I am hoping to dedicate a few hours every day after work to some sort of side-project or textbook studying to make myself more employable. Does anyone have any insight as to what may be worthwhile to do in order to have a more meaningful career?

Hi y'all,

I am currently studying Electrical Engineering, though I've really wanted to do Mechanical Engineering. My parents pushed me to go for EE and then later CE (Computer Engineering), because they believe that AI/ML is the future, and software development and all is where it's at. Though they aren't wrong, I am not really interested in all of that. I have never liked coding, and I have always sucked when it came to programming. All my life I really wanted to pursue hardware and design, and I love getting my hands dirty with the nitty gritty stuff. Learning about machines and all is stuff that I want to do, and while EE isn't bad, it isn't exactly the field that I want to pursue. Now, I tried to change my major into Mechanical Engineering, but god damn is it hard. You need like a straight 4.0 to even be considered and I am no where near close (3.57). I have engorged myself in clubs that involve hardware and stuff like car teams and robotics teams, where I would be in the mechanical team (non-mechanical engineer there lol) but doing stuff like that feels fulfilling and fun, and is something that I have always wanted to do.

So I am wondering if I should pursue a masters degree in Mechanical Engineering (I have done some of the basic courses like CAD, statics, dynamics, solid mechanics, thermodynamics) or if I should just instead transfer out to a different college and do a bachelors in Mechanical Engineering. I rather do like my life here at this college, transferring is a bit tough due to social pressures, but one day I would like to call myself a Mechanical Engineer, but I am unsure of the steps I should take in that regards.

TLDR I am currently stuck studying Electrical Engineering but I wanna study Mechanical Engineering. Should I try transferring out, or just pursuing a masters in Mechanical Engineering?

Hey everyone!

I am mech Eng with about 3.5 years experience. I plan on staying at my current company for another two.

I currently live in the northeast U.S. making about just north of 100k and have become very intimidated by even many modest homes selling for 400-450k. I know this is not entirely unique to the northeast, but the market up here is worse than elsewhere.

That said, what areas have a decent ME job market and decent housing affordability?

Thanks!

I have a circular bar supported by two journal bearings, one at its beginning and the other at some arbitrary length. From what I can see in statics textbooks a journal bearing does exert a reaction moment. Still, when I asked my instructor about it, he told me to ignore it and only consider the vertical reaction force without explaining why.

https://preview.redd.it/01oox06cx24e1.png?width=1106&format=png&auto=webp&s=43cb6a6b2961fc5c606974e2a44b54e2a851ce6d

FBD with reaction moments

FBD without reaction moments

From your experience which FBD better reflects reality?

https://preview.redd.it/e6nwr8vun14e1.png?width=925&format=png&auto=webp&s=fe4f7406eef86ddfd8e56ed91ea85843d4c96cc4

These are experimental value's from a testbench, I'm having difficulties adding the curves to a singular curve to create pump characteristics for Parallel and series.

There seems to be little to NO overlap for me to add Head, or Flows together.

I’m from a country where internships are only available if you’re at least a junior, but I want to apply for programs abroad and should upload a CV, except, well, mine is empty.

I want to dedicate this year to personal projects & such. Any ideas as to where to begin looking for ideas and as to what to add to a CV that is compelling enough for, say, internships abroad & summer programs?

I’ve been pondering something lately, and I figured I’d throw it out to the hive mind here. For those of us who chose Mechanical Engineering as our career path—whether in school or professionally—do you ever look back and think, “Was this the right choice?”

It’s hard not to compare ourselves to friends or colleagues in tech or management. You know, the ones who seem to land high-paying jobs right out of college or have more opportunities to switch industries. Meanwhile, we’re here, working with machines, CAD models, and manufacturing processes. Some days, it feels like we’re shaping the future of the physical world; other days, it feels like we’re lagging behind.

So, I’ve got some questions for my fellow mechies:

1. Do you regret taking mechanical engineering? If so, what would you do differently?
2. Compared to your peers in tech or management, how do you feel about where you are now?
3. What are the pros and cons you’ve experienced in this field?

For me, the love for engineering hasn’t faded, but sometimes the lack of cutting-edge job opportunities or slower career growth compared to tech feels like a downside. On the flip side, I’m proud of the tangible impact mechanical engineering has on the real world—building things that people can see, touch, and use.

Hi all, I am currently a second year mechanical student entering their third year. I have free time outside of work and I want to begin doing something productive to help with my career. Any advice on things you can do in your own time / skills you can learn that will help towards my ability to be an engineer / my career. Also open to hearing any advice about transition from uni to the workforce.

Many Thanks!

Hello! I'm at a crossroads with my company and we are looking to produce a baseball pitching machine. We operate in the baseball/softball vertical and are rapidly growing going into our second year. Currently we resell another companies machine, but our business has gotten to a point where I believe it makes sense for us to produce our own pitching machine in house.

1. What are the key considerations we should be aware of when designing a baseball pitching machine? I know all our specs for the machine, 1/4 hp motor, 10" diameter wheel, 50lbs, etc.
2. As a small company, what’s the best way to find and hire a mechanical engineer with the right experience for this project? Are there specific platforms or networks you would recommend?
3. Ideally we look into contracting with an engineering firm that can oversee the entire design and prototyping process. Should I be focused on finding someone local?
4. What kind of budget considerations should we be prepared for in the design and prototyping stages?

We appreciate any insights, resources, or advice you can share to help us kickstart this project on solid footing. Thank you!

https://preview.redd.it/vz2hrsrttz3e1.jpg?width=960&format=pjpg&auto=webp&s=56cc82770af9da13a574aaa4e73ba522540bafb3

Probably not the best place to ask this but I had trouble finding a more specific page (feel free to direct me). Im looking for a functional ICE model to get for my mechanic buddy for Christmas. Ideally a V8. Something he can assemble and either hand crank or have a heat source to power. Ive seen some models online but Id like some recommendations if anyone has one that has lasted some time. Dont want a super expensive one but i also dont want one thats gonna break after a few cycles. Looking to keep it under $50 if possible.

Hoping some controls engineers are bored on this lovely Friday afternoon, I'm very stuck on how to model this system in Simulink. Full disclosure, this is a project for my controls class. I've gotten all the help I've been able to find, but the holiday is making things tough.

Here's the problem statement:

Combined Plant/Actuator TF for Heating: 1/(100s + 1)

Combined Plant/Actuator TF For Cooling: 1/(120s + 1)

Thermocouple TF: 1/(.05s + 1)

Heat the box up from 72° F to 100° F in under 5 minutes and hold that temperature (+/- 1 degree) for at least 60 seconds Cool the box up from 100° F to 80° F in under 5 minutes and hold that temperature (+/- 1 degree) for at least 60 seconds

https://preview.redd.it/71bs7l0x5y3e1.png?width=1170&format=png&auto=webp&s=a0335f81b525433cb445a853fd97ea5736d2eb3b

I've modelled it as above, but I'm struggling to get the expected output. At the moment, I'm not using any controller as I'm able to use a controller of my choosing.

The biggest issue I'm having, I can't get either system to start at the desired temperature (72 for heating, 100 for cooling)

Step input is set as:

https://preview.redd.it/ui2tafsc7y3e1.png?width=576&format=png&auto=webp&s=03dec2ef59d7f4ec280b546062595f3fac152e2a

Graph looks like this:

https://preview.redd.it/6ribi6f27y3e1.png?width=695&format=png&auto=webp&s=dcafb8e8356e2832145a3f00c6ff676850016d19

What do I need to do to get the system to start at 72?