/r/engineering

Photograph via snooOG

r/engineering is a forum for engineering professionals to share information, knowledge, experience related to the principles & practices of the numerous engineering disciplines.

r/engineering is NOT for students to ask for guidance on selecting their major, or for homework / project help. Read the sidebar BEFORE posting.

If you see any post or comment that violates these rules, please report it so the moderators can respond in a timely manner. Thank you.

  1. No questions related to university, school, major selection, GPA, coursework, etc. NOTE: Asking for help on homework will result in an instant ban. DO NOT DO IT.

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  • Submission Flowchart

    Comment Rules
    1. Keep the discussion civil. Overly insulting or crass comments will be removed. Multiple violations will lead to ban. Racism, sexism, or any other form of bigotry will not be tolerated.

    2. Be substantive. No low-effort one-liner comments, memes, or off-topic replies. Limit the use of engineering jokes.

    3. Do not comment outside your area of competence. If you do not know about a topic, do not attempt to answer somebody's question. If you paste a comment that appears to be from an AI source, it will be removed. Multiple violations of this will result in a ban.

    What is r/engineering for?

    r/engineering is a forum for engineering professionals to share information, knowledge, experience related to the principles & practices of all types of engineering: civil, structural, mechanical, electrical, aerospace, chemical, computer, environmental, etc.

    Questions about current engineering projects you are working on, how to interpret codes and standards, and industry practices are all encouraged. Engineers should help each other to make the world a safer and better place.

    Images and videos related to engineering are acceptable, provided they are relevant to engineering. Completed projects, destructive test results, and unique machinery and hardware are all acceptable and encouraged. Lead-in comments are required to provide context to the readers.

    Need to Interview an Engineer?

    Pick an engineer from the list of volunteers below and send him or her a PM indicating that you would like to conduct an interview:


    Directory of Useful Subreddits

    Engineering Fields
    Engineering Topics
    • LearnEngineering: Learn & discuss engineering concepts
    • CAD: Computer Aided Design
    • CFD: Fluid Dynamics
    • FEA: Finite Element Analysis
    • PLC: Programmable Logic Controllers
    General Science
    Textbooks
    Other Links

    /r/engineering

    483,376 Subscribers

    5

    Whats the latest CAD features and development?

    Curious as im out of the loop for CAD for a while and want to get back into it. Heard great things about onshape.

    Would like to also try generative design at some point too.

    10 Comments
    2024/06/11
    20:53 UTC

    1

    HVAC Engineers: Help reading Circuit Setter valve flow curve.

    This is a bell and gossett flow performance curve for a 1.5" balance valve in an HVAC application controlling flow on the chilled water service to air compressors.

    The product literature from B&G doesnt have a legend so i'm assuming the curves on the figure is the Cv at each flow? For example, 9.4 GPM thru the valve has a Cv of 26.

    Is this how you would read this? Any experience with B&G flow curves like this? I have not a curve this vague before...

    https://preview.redd.it/1uorojw6106d1.jpg?width=1020&format=pjpg&auto=webp&s=778e0e0f020648f1c7107811dbc663d91614a23b

    1 Comment
    2024/06/11
    20:04 UTC

    3

    Looking for a specific quick disconnect stainless steel part

    Where I can a part this is like this (https://www.amazon.com/Hansen-Straight-Through-Hydraulic-Fitting/dp/B00F4IEHJI?ref\_=ast\_sto\_dp) but in stainless steel and I need the threading to be straight and not tapered. Or any pointers on keywords I should look for? I have been searching everywhere but the closest thing I have found was this (https://www.amazon.com/IORMAN-Female-Quick-Disconnect-Adapter-Stainless/dp/B07NYVW1DS?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=A2R9EC5ORWAMJN) however it says that it is used for air, I need it to be used for liquids. Any help would be greatly appreciated!

    6 Comments
    2024/06/11
    16:09 UTC

    0

    How do is stop washers from transferring power on sleeve bearing?

    The exact context of the project is isn't important. the situation is as shown by this image, where I have two "cylinders" with sleeve bearing on the shaft that are stabilized and spaced by metal washers.

    The problem is, I need to keep the parts very tightly together to meet a standard length, and so often the washers transfer power between the parts, aka make the disk rotate when it isn't supposed to because the pervious disk rotated.

    some solutions I tried:

    1. sand down the washers very smoothly (didn't work)

    2. make new washers with tighter inner diameter so they can never rotate (this made friction wayyy too high and led to this disaster as I couldn't get them out)

    3. put 2 washers instead of 1 so they're less likely to transfer power (eventually they do still!)

    help is appreciated

    9 Comments
    2024/06/10
    06:44 UTC

    1

    Blasting and coating procedure ((IM80)

    Guys,

    I am reaching out again for help with procedures for BP.

    I need something in alignment with IM80

    1 Comment
    2024/06/09
    08:35 UTC

    16

    What resources do you use to find high quality online training/courses?

    Hey everyone,

    I'm a robotics engineer and my company has generous training budgets which I "need" to use up if possible. I would love to find an advanced course about AI, or embedded systems, or maybe some highly specific programming course. I'm also really trying to pivot into the space field, so anything about orbital mechanics, aerodynamics, etc. would be awesome. What resources do you use to find very high quality online courses? Udemy? Brilliant.org? Something else? I've never really paid for courses before because I usually find all I need online or reading papers, but I "need" to use up this budget for reasons...

    Thanks so much :)

    10 Comments
    2024/06/08
    16:36 UTC

    53

    A day in the life of an engineer

    It's been a while since we've hosted one of these threads, and since we do get periodic inquiries from readers, please share what a day in your life looks like. Feel free to share as little or as much detail as you like, but at least include how many years of experience you have, your title, and your field as these will provide useful context to readers. If you wish, you may list your salary and location, but this is absolutely not a requirement.

    The last one I recall was this one in case you want to get an idea of the kinds of things people posted.

    70 Comments
    2024/06/07
    17:41 UTC

    2

    Low Operating Temp Camera on a budget

    I've posted another question related to this test previously and received great advice!

    I'm wanting to observe displacement of cabling with a high CTE against a CF support structure. For areas of concern, I'm planning to print a grid of 0.5mm or 1mm lines (another problem) and record the test using a telecentric lens from edmundsoptics.

    I am balancing my familiarity with consumer cameras and budget for small research projects and trying to avoid buying both a $3k lens and a $5k camera, so the package I've selected is an F mount lens and a Nikon D500. Unfortunately, my test will be at -55C. At the moment, I'm planning to build an insulated box with a double paned viewing window and a heater to keep the equipment happy in the cold chamber.

    It would be a lot easier, however, if I could find a camera that operates in or near that temperature such as an astrophotography camera. Does anyone know of affordable cameras with video feature that are much closer to this operating temperature for below $1.5k?

    I've done my share of googling and found it was difficult to parse through the results as I believe googles tendency to push consumer products for ad revenue has me clicking through every link before finding the products are inadequate.

    Thanks!

    5 Comments
    2024/06/07
    16:55 UTC

    10

    Independent contracting and liability protection

    Question to any Freelancers / Contractors / Consultants out there:

    I'm shifting to freelance after 11-12 years of experience full time doing tooling and machine design work in aerospace. I have set up an LLC, separate bank account, etc but I'm a little unclear about what (if any) additional protections I should be putting in place before accepting work. I'm not a PE so my work would be limited to things that don't require that. I've worked on a number of machines, lift fixtures, etc that are safety critical but as a full time employee my understanding is that my employers largely accepted the legal burden if there were ever to be an issue. Thankfully that hasn't ever happened but I'm terrified about what that would look like now that I'm operating independently. I'd expect to be working on those same types of projects as a contractor.

    So some questions on my mind:

    1. Are there any specific types of insurance I should be getting? Errors and Omissions? General Liability? something else?
    2. Is it common to have a contract in place that basically shifts the burden to the client or manages the liability in some other way? I could imagine this being set up where once they approve of a design, drawing, whatever, they are now responsible. But I could also see why a client would not want to sign such a document so not sure about that.
    3. Are there any particular projects I just shouldn't even consider in this position? One close friend in a similar position said for example he won't touch lift fixtures. I have a lot of experience designing those so it would be a shame to have to avoid them entirely.

    Any guidance would be greatly appreciated!

    10 Comments
    2024/06/05
    18:10 UTC

    14

    Bag for Field work

    I am looking for a good bag that I can use for field work inside and outside of plants. I cant seem to find anything that is wide enough to carry the 11x17 drawings. I am tired of having to fold them in half not to mention the longer clipboard sticking out of my bag. I tend to carry a good bit on me so I am looking for a bag that can not only hold 11x17 drawings but also general supplies and some tools like lasers, levels, tape measure, that kind of stuff. Anyone have anything like that?

    26 Comments
    2024/06/05
    01:40 UTC

    1

    Flexible material for +/-360 degree rotation in Torsion

    I'm trying to find a tubular (or can be made tubular) fabric type material that is able to "twist" +/- 360 degrees in Torsion over a small distance (about 2") ideally it would be resistant to dust particles etc. it would need to cycle +360 to -360 a lot maybe 50-100k cycles.

    13 Comments
    2024/06/04
    13:34 UTC

    2

    Open source Separator design software

    Good morning all,

    I need some reccomendations on either excel sheets or software to validate a process design calc.

    12 Comments
    2024/06/04
    07:18 UTC

    26

    What are the latest trends in your field?

    Whats the current predictions for where things could go in your field or whats needs to go.

    64 Comments
    2024/06/03
    21:00 UTC

    0

    Temperature gradient in a still pipe, heated on one end

    Need help finding a way to predict the temperature profile in a pipe that's heated on one side. Basically one end of the pipe has a constant heat flux, and I want to be able to calculate the temperature at each end at a given time. It's filled with fluid and has a mix of horizontal and vertical sections, and includes losses to the atmosphere.

    Really struggling with how to even formulate this problem. My first thought was to use the Finite Element Method, but I believe that is only valid for pure conduction, and I don't think that's the case in this problem. Then I looked at natural convection in enclosures, but couldn't find any formulas that apply to this geometry, for a while I thought a vertical rectangular could work, but it's only valid for H/L>1.

    Finally thought I was getting somewhere when I found some academic papers on the subject. They say that the temperature of the fluid in the pipe is only dependent on y and not x, because the natural convection actually causes some flow, so the upper portion of the fluid is moving away from the heated end, and the lower portion is moving towards it. In which case you could model the system as the entire volume of fluid being heated by the heat flux. While I understand that conceptually, I have to believe that it only applies for short pipe lengths. Something over 100m in length would have to have a gradient of some sort.

    Any ideas on where to start with this?

    8 Comments
    2024/06/03
    19:58 UTC

    1

    Crane Rail Profile Resource

    Hello,

    I am looking for a reliable resource that has all of the dimensions for crane rail profiles. A lot of websites such as: centralsupply, integritycrane, cranrailsupply and tx holdings have readily available charts that show some of the dimensions, and solidworks provides a set of profiles in the structural member feature menu, but I am looking for the precise dimensions (including top-of-head radii) for 75# crane rail and can't seem to find it anywhere. The AISC steel construction manual table 1-21 (16th edition) wasn't much help either. Anyone have a good pdf or something? I know 75# rail isn't that common but this information should be somewhere.

    3 Comments
    2024/06/03
    16:51 UTC

    2

    Shear Calculation Help!

    Hello!

    I am trying to figure out the Shear Capacity for a 2x12 ledger board that is bolted into the side of an existing Masonry wall that has brick siding using a 5/8" DIA. steel anchor bolt @ 16" O.C. and am finding myself a bit out of my element when googling online and looking at all the different calculators and modules, any help would be appreciated!

    5 Comments
    2024/06/03
    13:59 UTC

    1

    Weekly Career Discussion Thread (03 Jun 2024)

    Intro

    Welcome to the weekly career discussion thread, where you can talk about all career & professional topics. Topics may include:

    • Professional career guidance & questions; e.g. job hunting advice, job offers comparisons, how to network

    • Educational guidance & questions; e.g. what engineering discipline to major in, which university is good,

    • Feedback on your résumé, CV, cover letter, etc.

    • The job market, compensation, relocation, and other topics on the economics of engineering.

    [Archive of past threads]


    Guidelines

    1. Before asking any questions, consult the AskEngineers wiki. There are detailed answers to common questions on:
    • Job compensation
    • Cost of Living adjustments
    • Advice for how to decide on an engineering major
    • How to choose which university to attend
    1. Most subreddit rules still apply and will be enforced, especially R7 and R9 (with the obvious exceptions of R1 and R3)

    2. Job POSTINGS must go into the latest Quarterly Hiring Thread. Any that are posted here will be removed, and you'll be kindly redirected to the hiring thread.

    3. Do not request interviews in this thread! If you need to interview an engineer for your school assignment, use the list in the sidebar.

    Resources

    24 Comments
    2024/06/03
    10:00 UTC

    7

    ‘Rising rate’ or ‘non-linear’ lever/linkage - how to design?

    I’m looking for suggestions on how to create a linkage that reverses motion and is linear at one end and travels non linearly at the other…

    I have a car with a cable operated throttle (a 1998 Lotus Elise). At the throttle body end, the throttle cable is just linked directly to the mechanism that opens the butterflies for each port. There is no sort of ‘cam arrangement” there like you see on old cars with carburettors etc.

    At the throttle pedal end, there is a simple ‘reverse motion‘ linkage like this: https://cdn.shopify.com/s/files/1/0615/2193/files/linkages_1_480x480.png?v=1680383999

    i.e. a simple lever with a pivot in the middle. One end is connected to the throttle pedal (which pulls a short solid bar attached the the linkage and pedal with spherical joints - to allow I guess for the arc’ed path of the fixing on the lever as the pedal is depressed), the other end is connected to the throttle cable. So there is a constant and linear relationship between movement of pedal and travel of throttle cable.

    my car has individual throttle bodies which is not the OEM set up. With this throttle system, very small changes in the amount of throttle opening create large changes in air flow volume. The result of this, with the current set up, is that the car is hard to drive smoothly with small throttle openings/light load.

    i want to replace or modify the linkage with one that places, say, the first 3rd of the throttle cable travel across the first 50% of pedal travel, and then becomes more sensitive (ie more throttle opening for less pedal travel) in the later portions of the pedal travel. It might be useful to be able to vary this to find a sensible ‘curve’

    how do I design a simple reverse motion linkage that is non linear or rising rate at one end?

    im not an enginee, but i am scientist (oh dear, you say), i’ve looked at loads of standard linkage designs and a can’t find anything, and I don’t (yet?) understand the principles of linkages to work it out myself! Does anyone have suggestions?

    (I don’t want to go to DBW throttles - way too complicated!).

    6 Comments
    2024/06/02
    08:21 UTC

    1

    PCB/PCA - When to Revise Drawings vs Issuing New Drawing Number?

    I'm working on some drawing modifications for a Printed Circuit Board (PCB) and Printed Circuit Assembly (PCA), and it's got me thinking more critically about when to issue a drawing revision and when to assign a new drawing number. I've got 3 scenarios in mind and I am curious what the community would think about each.

    Scenario #1:
    A legacy (25+ year old) PCB design was sent out for fab and the fabricator asks whether they could increase one dimension of the board by 0.020" so that it satisfies current revisions of the IPC standards. We give the green-light, and they create a Manufacturing Deviation Record to document the change and fabricate the boards with no change to the DWG number or revision on the silkscreen or manufacturing documentation.

    Since the physical item is labeled with the old drawing and rev, the only real option we have to document the change on our side is an unincorporated ECO appended to the original drawing. But should we have instead created a new drawing or revised the old one?

    Conventional wisdom says issue a new Drawing number when there's a change to form, fit, or function and especially when the new article is not interchangeable with the previous one. One one hand, the change in board dimension did NOT affect our use of the board -- we are using it exactly as we did the old one. On the other hand, they are physically different sizes and in an application where the size were more critical, they might not be interchangeable.

    Scenario #2:
    A printed circuit board is built and during bring-up it's discovered that one of the line drivers was laid-out backwards (output connected to output and input connected to input). Obviously, the design failed to meet part of its functional requirements and needs to be corrected. Should that correction be documented in a new revision under the same drawing number or under a completely new drawing?

    The board with the correct layout is NOT interchangeable with the previous design since one works and one does not. On the other hand, their indented use is the same in the next-higher-level assembly.

    As you prototype and correct design issues, are you rev'ing drawings or creating new part numbers?

    Scenario #3:
    Another part of the product has changed and requires a resistor value on a Printed Circuit Assembly to change in order for the whole thing to work.

    Different resistor values definitely prevent the boards from being 1-1 interchangeable, but we intend to use them in the same exact way. New drawing number or new rev?

    An alternative solution might be "BOM" variants, which I've used at previous companies, but our current drawing number system is not built to accommodate.

    3 Comments
    2024/06/01
    18:34 UTC

    3

    Angular velocity of planet gear

    What is the correct way of determining the angular velocity (rotational speed) of the planet gears in a planetary gear set where the sun and carriers rpm is known and the ring gear is fixed? The sun is the input and carrier the output.

    I have found several formulas and explanations but they all lead to different results so i am obviously missing something.

    5 Comments
    2024/06/01
    07:50 UTC

    1

    How to appropriately filter noisy dynamic tensile test data?

    Hello there, I performed some dynamic tensile tests in the strain rate range of 80/s to 700/s on polymer specimens and am now in the process of cleaning the data. I assume that the oscillations stem from the impact exciting the impactor, sample bracket and load cell (+mount) assembly, and that the oscillation frequency therefore is near identical across all files. My question now is how to appropriately filter the results, since I know barely anything about filtering and signal processing. Trying the different algorithms of the data cleaner tool in Matlab, the Savitzky-Golay filter seems to produce "nice" results. But how can I determine adequate settings for the filter or if it's the right choice at all? I have a set of 200 samples at different speeds and ductility levels, therefore it would be best that the settings work for all the files since I need to process them in batch. Two such signal examples are shown below. Thanks!

    https://preview.redd.it/k0yozsck7r3d1.png?width=1409&format=png&auto=webp&s=880daebdc9c85f1b567a4ffafae61d794169c01a

    https://preview.redd.it/ff437qms7r3d1.png?width=1454&format=png&auto=webp&s=63dd717961359fb294f63f381e496966ac88f831

    11 Comments
    2024/05/31
    12:24 UTC

    3

    Where can i find coating procedure templates?

    I have to apply a Hempel product and need a procedure.

    I have the technical docs and data sheets but need a sample to follow. Any ideas?

    2 Comments
    2024/05/30
    15:58 UTC

    1

    Safety Standards, Rocket Stove

    Hello!

    I am working on a start up fabrication company, and in order to raise funds for equipment, we decided to bring one of our ideas to market.

    Over the past couple years, I’ve built several prototypes of a wood pellet burning rocket stove for camping, and potentially outdoor cooking. It works quite well, and several people have expressed interest in purchasing these. We can streamline the build, and make several of these stoves. It would be for outdoor use only and in areas away from combustibles. In my mind, safety wise, very similar to your standard fire pit. Don’t light it in your garage, living room, or next to your leaking lawn mower. Place it on stable ground, etc.

    That said, I spoke with a few attorneys who are willing to help me write a disclaimer for customers. I would like to go a step further and take a look at the design and see if I can bring it in line with either UL standards, or some other standard issuing body.

    I can’t seem to find any code or standard that applies to an outdoor pellet burning stove (gravity fed). I want to protect our new company from liabilities the best I can, and am willing to go the extra mile as long as I can swing the cost.

    My goal is to sell these and be as protected as possible from people who may touch the stove while in use, kick it over, etc. The disclaimer may help with that, but designing to certain safety standards ‘feels’ like it will protect us even further.

    Does anyone have any suggestions on how we can proceed? Maybe which standards apply? These will be sold in Ohio, and potentially across the US. Would any of you go for it and just sell these with just a disclaimer, or do you feel it should be certified by UL or similar?

    I appreciate anyone’s input on this. Thank you.

    8 Comments
    2024/05/30
    05:28 UTC

    2

    How would you test the NM torque of a rotating axis?

    Looking to test the torque of screwdrivers by connecting then to an axis and running them. Not sure what set up i could use to measure this or calculate it

    17 Comments
    2024/05/29
    16:21 UTC

    15

    Engineering practices/cultures around the world?

    Reading Koen's Discussion of the Method, came across this bit:

    I cannot certify from personal experience the observation of the English engineer Gordon Glegg, writing in The Science of Design:

    "Rightly or wrongly, the U.S.A. has the reputation of being able to develop a new invention much more readily than we do in this country. If this is true, it may well be that one of the reasons for it is that the Americans usually veto any improvement in design after construction has begun. Leave it alone and alter the design in the next machine or the next batch; don't tinker with this one is their policy. And it is a highly realistic one."

    If this statement accurately describes engineering design in England, it expresses a significant difference in the engineering practice of two countries with respect to the engineering.

    Never thought of engineering being like boxing or judo, with significantly different regional styles being known, but I could see it. For those with more international experience, what do you think?

    22 Comments
    2024/05/29
    12:55 UTC

    1

    Question on Metallurgical and Materials PE

    Hello all, I will be taking the PE exam this coming October for MSE peeps.

    I have reviewed the reference handbook, and am now reviewing the MSE Holy Grail textbook, Introduction to Materials Science and Engineering by Callister Jr.

    I am asking for advice on literature to review, as well as problem sets to practice with. One big part of the review I am missing is problems to work on! I only have 2 practice exams to work with, and am desperate for more material to study. I have plenty of time, so all I need is the material!

    Does anyone have experience with the TMS PE Materials course? It's expensive at $1250, but I will happily pay if anyone has information to share.

    Thanks!

    1 Comment
    2024/05/29
    01:02 UTC

    5

    Seeking a replacement for our Repligen HFM filters

    Right now we're using these style membranes for filtration. Originally they were our only choice due to their 2-4um pore size, but it's been a few years since we last revisited the subject. Does anyone know of any other filters in the 2-4um range for bio processes?

    1 Comment
    2024/05/28
    19:17 UTC

    2

    Weekly Career Discussion Thread (27 May 2024)

    Intro

    Welcome to the weekly career discussion thread, where you can talk about all career & professional topics. Topics may include:

    • Professional career guidance & questions; e.g. job hunting advice, job offers comparisons, how to network

    • Educational guidance & questions; e.g. what engineering discipline to major in, which university is good,

    • Feedback on your résumé, CV, cover letter, etc.

    • The job market, compensation, relocation, and other topics on the economics of engineering.

    [Archive of past threads]


    Guidelines

    1. Before asking any questions, consult the AskEngineers wiki. There are detailed answers to common questions on:
    • Job compensation
    • Cost of Living adjustments
    • Advice for how to decide on an engineering major
    • How to choose which university to attend
    1. Most subreddit rules still apply and will be enforced, especially R7 and R9 (with the obvious exceptions of R1 and R3)

    2. Job POSTINGS must go into the latest Quarterly Hiring Thread. Any that are posted here will be removed, and you'll be kindly redirected to the hiring thread.

    3. Do not request interviews in this thread! If you need to interview an engineer for your school assignment, use the list in the sidebar.

    Resources

    22 Comments
    2024/05/27
    10:00 UTC

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