/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

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    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.

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    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.

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    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
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    Other Links

    /r/engineering

    480,546 Subscribers

    78

    Move fast, break things, be mediocre

    Is anyone else fed up with the latest trend of engineering practices? I see our 3D printer is being used in lieu of engineering - quickly CAD something up, print, realise it doesn't go together, repeat until 2 weeks have passed.

    Congrats, you now have a pile of waste plastic and maybe a prototype that works - you then order a metal prototype which, a month later, surprise, won't bend into your will into fitting.

    Complain about the manufacturer not following the GD&T symbols that were thrown onto the page, management buys it and thinks this is "best practice", repeat.

    27 Comments
    2024/05/11
    16:08 UTC

    3

    Reducing excessive foaming when puring liquid soap into reactor

    We have a reactor where we pour hot liquid soap to homogenize. We are trying to load two batches into the reactor to optimize double batch productions. However when puring the first batch it generates an excessive amount of foam that prevents us from loading the second batch.

    First we pured it from the top of the reactor, which created massive amounts of foam.

    After that we tried puring it through a pipe with an opening close to the base of the reactor. The pipe had curves to control the speed at which the soap fell through it. Problem with this is that when we introduced the second batch it didn't properly homogenized with the first batch, since the first batch move to the top and the second one stayed at the bottom.

    Finally we tried pouring the soap into the walls of the reactor, but as with the other first method it still generated too much foam to allow us to combine to batches in the reactor.

    We can not change the production process, only the way we pour or introduce the first batch into the reactor, and both batches have to be introduced in the same manner into the reactor since there's only one line of production.

    Any suggestions? English is not my first language so apologies for any missues of any technical word.

    10 Comments
    2024/05/10
    20:19 UTC

    0

    What machines can I salvage gears from, for a ratio of 25:1 to 75:1 and 120 Nm?

    For a muralist machine prototype I want to salvage precise gears that can handle 15 kilos and 150Nm, from a car transmission, a lawnmower, a tractor, a milling stone. I dunno... However, car 1st gear and reverse are about 4:1 ratio, so the most I can get from them is 16:1 and I want 50:1 ratio... I am powering it with an 8 lbs stepper motor that runs 5A. I'd like some advice. Cheers!

    9 Comments
    2024/05/10
    13:13 UTC

    1

    Separator Design Question

    We are constructing a carbon steel separator with stainless steel internals

    My question concerns the angle iron that forms a lip circumfrential to the shell. It is SS with SS a perforated plate on top

    Why would you not avoid the dis similar weld, use a CS angle and put rubber between the angle iron lip and ss plate?

    I dont have acces to the designer to ask. More construction based.

    4 Comments
    2024/05/10
    03:05 UTC

    8

    Building a desktop record and play robot arm

    0 Comments
    2024/05/09
    14:28 UTC

    5

    Would this spring design work?

    https://preview.redd.it/55qh98lh0bzc1.jpg?width=1712&format=pjpg&auto=webp&s=a76152921ed2cdccd8d7653abbc2b94130fcf3b4

    I'm designing a part with a spring in it, but have a very thin profile to work with (~0.8mm).

    I've calculated that in order to avoid permanent deformation, I need a flat spring that's ~3.5mm wide, but again, I only have 0.8mm of width to work with.

    So, could I instead have a few smaller sections of material that are each 0.8mm thick, but add up to 3.5mm?

    I drew a quick picture of what I'm thinking above. Is this crazy, or would this work?

    (I'm not an engineer, for context.)

    10 Comments
    2024/05/09
    01:36 UTC

    5

    Working outside your state

    Let's say engineer A is licensed in state 1, but they have a client that needs work done in state 2, which engineer A does not carry a license. Can engineer A complete all the work, then hire engineer B, who is licensed in state 2, to review and stamp the work completed by engineer A?

    I have seen engineers do this all the time, however an engineer today said that they would have to maintain direction and control of the project, then contract out the engineer who is bringing them the work, in order for them to stamp the drawings. Just curious what everyone's opinion is on this. or if this standard is different in different states.

    35 Comments
    2024/05/08
    20:34 UTC

    5

    Thoughts on this crane hurricane tie down weld

    36 ton outdoor bridge crane

    Hurricane tie downs for a 100mph wind / 300kN/68,000 lb horizontal force

    Concrete slab with a 1.5” flat plate bolted to the top. Welded to the top of the plate are two 10”x 16” lugs made out of 2.5” plate with 3” holes for shackles to pass through.

    This all makes sense to me as a dumb construction dude. What doesn’t make sense to me is that the 2.5” plate is only welded to the 1.5” plate with a 10mm perimeter fillet weld. Perimeter is 69”.

    From anything I’ve done before, seems like either the weld is undersized or the plate is oversized. Any insight from those with design knowledge?

    8 Comments
    2024/05/08
    18:08 UTC

    1

    Corrosion inhibitor for Hydrotesting

    Good morbing all,

    I am looking for a corrosion inhibitor for Carbon Steel pipe.

    The water will be in ghe line for 2-3 days and we will blow down. But my scope asked for an inhibitor.

    The hydro test contractor said ethyle glycol can be used but i am not sure about that.

    Afaik, ethyl glycol is a coolant and i dont know that you can add that to water as an inhibitor.

    Please advise.

    13 Comments
    2024/05/08
    16:49 UTC

    15

    Checking an installed bolt torque

    If I have a bolt that should be installed to 200 Nm by the spec, and a couple of weeks later I want to know whether it was installed to roughly that, what would be the best way to go about that?

    I am expecting pitfalls with static friction that mean it isn't as simple as setting the torque wrench to 200/220/240 and seeing when it clicks. I had read doing that will give a higher value than what was initially used, but was struggling to find any values for how much higher I might expect. i.e if it's meant to be 200 and the wrench clicks at 220 is this an indicator of overtorquing.

    20 Comments
    2024/05/08
    15:36 UTC

    0

    Weekly Career Discussion Thread (06 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

    29 Comments
    2024/05/06
    10:00 UTC

    0

    What is a good S value for X65 material?

    Good day,

    I was looking over calcs from a senior design engineer and saw that they used 22 ksi for x65 material.

    I was wondering why this was the case.

    Some components on the item are SA105 while others are matched with the X65 pipe. I dont know if that is why.

    18 Comments
    2024/05/04
    09:08 UTC

    2

    Calibration Standards Help?

    Relatively new to manufacturing so I’m still trying to get a grasp on the rules and standards. I work in an automotive manufacturing plant (plastics) in quality- we are certified to IATF 16949/ISO 14001:2015. I’m in charge of staying on top of our calibration cycles, and I’m looking into doing our calibration of small tools internally- calipers and micrometers mostly, and outsourcing all of our other larger gages. My question is how can I do this and be in compliance?

    I’m having a hard time understanding what’s allowed, so:

    1. Do we need a temperature controlled room for calibrating small tools?
    2. We have a brand new set of gage blocks, and the paperwork that came with it said it Ian certified to ISO/IEC 17025 as of January 2023, and meets requirements of ASME B89.1.9-2002; can I use these for verifying calipers, or do I need to send the blocks to be verified by another company first?
    3. On that note, how long is a standard calibration cycle on gage blocks? Is it just based on wear and frequency of use?

    I’m hoping someone can help me with these, since it would save us a good bit of money and 3+ weeks downtime every time we have to send out calipers. I just don’t want to get hit in an audit by doing something wrong. Thanks in advance!

    6 Comments
    2024/05/03
    15:56 UTC

    0

    Why are Long Weld Necf flanges used?

    Why cant you use wn and heavy eall piping? Is it to save a weld?

    6 Comments
    2024/05/03
    02:07 UTC

    1

    Any recommendations for a good water resource engineering handbook?

    I'm not an engineer, and I have a background in the humanities. However, at my current job, I work a lot with hydrologists, hydrogeologists, and water resource engineers (both surface and groundwater) and need to have a better grasp on what they do. To be clear, this is not quality. It is water rights. Are there any "water engineering for dummies" type books you would recommend? Its OK if its technical, that may be ideal considering how often I read technical engineering reports.

    1 Comment
    2024/05/02
    22:41 UTC

    0

    Lessons learnt for Design/Fabrication of ASME vessels.

    Good day all,

    Looking to put together a Lessons learnt for a ASME U/R stamp vessels and a Pig Reciever.

    Anything you can share? Im new to this type of work and but want to put up some examples for my team to add to or use as a jumpibg off point.

    All i have is that we dont like Lincon 70S-2 rods as they leave a residue between passes.

    General fabrication error. Fab checker role made redundant due to cost cutting.

    Drafting errors

    Please contribute a few ideas

    5 Comments
    2024/05/02
    01:59 UTC

    0

    Design considerations to improve a home CNC?

    I want to rebuild my 'desktop scale' cnc mill into something more capable.

    However, I'm finding too much variation in the designs of industrial CNC mills to understand how they compare

    In desktop CNC's there is very little variation in format, it seems like they all follow the same basic blueprint, which makes me skeptical that it's actually a well considered format.

    My skepticism is fueled by the way 3D printers have fallen into 'follow the leader' patterns in the past. For a long while they all had the 'guillotine' frame with a sliding build platform, now with the Voron, RatRig, BambuLab etc. everyone has changed their mind on the best format, and now 3D printers are all cube frames with CoreXY belt configured XY axiis

    So yeah, it's hard to design when I'm not informed enough to properly judge and compare designs.

    2 Comments
    2024/04/30
    13:24 UTC

    256

    How has cybertruck dealt with galvanic corrosion between the castings and panels?

    I noticed that the cybertruck has some fairly large castings that appear to be the important structurally, but the car also quite obviously has large stainless panels. I have seen in some videos that the castings seem to have something like a black coating over most of their surface, but there are bound to be openings where water can meet a bimetallic area.

    Does anybody know what strategy they’ve used to keep these castings from being attacked?

    169 Comments
    2024/04/29
    15:39 UTC

    2

    Weekly Career Discussion Thread (29 Apr 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

    36 Comments
    2024/04/29
    10:00 UTC

    3

    Preventative Maintence Template

    Good day

    Im helping out a friend, woth the hope to get full time work from this

    To set up a preventative maintence programme

    They dont want to use software just yet... so we were thinik using excel.

    Any ideas of free tools or excel templates?

    What woyld you look for in this setup

    My background is fabrication so not much of this type of work.

    2 Comments
    2024/04/29
    00:26 UTC

    3

    Pressure effect of octagon vs round rolled pipe

    I have a question for process guys or those familiar with liquid performance in pipe.

    I am a fly on the wall to a discussion and i want some information .

    We have two options for a sand jetter:

    1. Is a 5ft octagon using 45 deg elbows and pipe.

    The other is 2. A rolled pipe option, 5ft od.

    In both cases the pipe is 2inch dia. I am wondering if it makes a difference at all?

    The mechanical designer thinks the octagon gives more control over pressure wheras the process designer gave us a round, rolled option with 2 flanges.

    This is my theory of understanding. I dont know if the round option leads to increaced velocity and reduced pressure while the elbows break velocity keeping pressure more stable thru the loop

    8 Comments
    2024/04/28
    08:03 UTC

    0

    Pig reciever Design

    Good day,

    Recenlty started with a vessel company. I wont be doing design/Fea as im new

    But i want to learn a bit about the EPC process for it.

    I suppose i will be doing moslty PM, procurment and Qc type work.

    I still want to have a good shedule, risk register and lessons learnt.

    So far we hav had issues with the deisgner not showing thermal , siesmic and nozel loadings.

    Is there some way i ca get the client to agree to particular ug calcs ahead of time?

    Only a month in and learning alot and want some ideas to be sucessful.

    5 Comments
    2024/04/27
    12:52 UTC

    8

    Zinc-plated SS Washer shim?

    We are working on reverse engineering multiple parts of a valve and one of the components is a ring shim that acts as a spring guide, which should be simple enough. However, when we sent it for material identification, it came back as zinc-plated stainless steel.

    Does this sound weird to anyone else? It's a European spec of stainless steel, but that shouldn't matter. Usually washers/shims are one or the other as far as Zn or SS. The only thing I can think of is the plating is for stability since the piece is .02" thick.

    22 Comments
    2024/04/25
    20:36 UTC

    12

    How would I go about building a automatic TCG sorter

    Basically looking to build something that would sort my magic cards automatically for me. It would be able to do it based off a lot of different options. It would scan it and then move it to a pile of some sort of the same type. What skills would I need to start learning to be able to do this? I know I'd need to program and some electrical components but what else? Also how expensive would one estimate something like this to be on a smaller scale?

    Edit: I appreciate all of the response and am seriously interested in doing this. I think the best route would be do use some sort of vacuum that would pick it up and place the card in a box or pile of my choosing. Otherwise I could set it up horizontally or at an angle with a lever at the bottom that would flip when the cord has been recognized and drop into something that would move it over a pile of the same type. I'm just having trouble with the image recognition part.

    17 Comments
    2024/04/25
    05:34 UTC

    4

    Test pressure for timed leak-down test

    I could use a sounding board here.... I'm setting up a timed leak-down test for a piece of "air-tight" equipment I just designed. Looking elsewhere on the web, I see that leak rate in SCCM (Standard Cubic Centimeters per Minute) is defined as:

    Leak Rate (SCCM) = (ΔP x V)/(Δt x ATM). Where ΔP = drop in pressure over the designated test time, Δt is the test time, V is the free volume inside the unit under test (UUT), and ATM is one atmosphere of pressure (14.7 psi).

    Thinking through the units this looks good; the resulting units will be volume/time (cc's per minute). Now I want to solve the formula for ΔP so I can establish the allowable pressure drop for my timed test:

    ΔP = (Leak Rate (SCCM) x Δt x ATM)/V.

    Now say my allowable leak rate is 0.5 cc/min, my volume V is 175 cc, and my test time Δt is 20 minutes. So my allowable pressure drop ΔP in that time is (0.5 cc/min x 20 min x 14.7 psi)/175 cc = .84 psi. Any unit that loses less than that amount passes the test. So here's the question; why doesn't the pressure at which I pressurize my UUT figure into the math? That is, why doesn't it appear anywhere in the equation? It seems critical to the matter. If I pressurize my system at 100 psi it's going to leak much faster than if I pressurize at 5 psi, for example.

    Writing this all out has made me think it through a bit more. I suspect the answer has to do with it being Standard cc's per minute, where standard conditions are : 20°C (68°F) and 101.3 kPa (14.7 psig). So does that mean I need to do my test at 14.7psig for the equation above to be used? What if I want to use 30 psig? Thanks

    17 Comments
    2024/04/24
    17:30 UTC

    3

    Dielectric Testing

    I am trying to find "hemispherical electrodes 12.7mm in diameter" per the Standard Test Method for Dielectric Testing (D149-20) but I can not find anywhere to buy that specific electrode for testing potting.

    Has anyone ever found a place to by that specific electrode?

    4 Comments
    2024/04/23
    01:32 UTC

    1

    Weekly Career Discussion Thread (22 Apr 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

    47 Comments
    2024/04/22
    10:00 UTC

    3

    Advice Needed on Multi-Sensor Development for Detecting VOCs, Fragrances, Mold, and Endotoxins

    Hey everyone, I am in the very early stages of exploring the development of a sensor system aimed at detecting VOCs/fragrances, mold spores/fragments, and bacterial endotoxins.

    The goal is to integrate this system into a user-friendly device, potentially connecting with smartphones, to help people with sensitivities to these things test and monitor their environments over time. Another goal would be to dramatically reduce the cost of testing which is currently done via PCR analysis of dust samples (for mold).

    I've been looking at the following sensor types:

    • PID Sensors (photoionization detectors) for VOCs and fragrances due to their sensitivity and response time.
    • Optical Sensors for their potential in non-invasive and continuous monitoring (mold spores/fragments).
    • Biosensors developed for detecting bacterial endotoxins and possibly mold.

    I'm reaching out to this community for advice on a few key points:

    1. Engineering Expertise: What type of engineers or specialists would you recommend collaborating with to ensure comprehensive coverage of the sensor development?
    2. Material and Design Suggestions: Any recommendations on materials or design elements that could enhance the sensitivity and selectivity of these sensors towards the specific substances we are targeting?
    3. Integration Challenges: Insights on integrating these sensors into a single compact device that could communicate with mobile platforms. Does physics allow this?
    4. Any Existing Solutions: Are there existing solutions or technologies that you think could be adapted or improved upon for this application?

    Additionally one of the biggest obstacles of course is cost, and one of the main goals here is to find a way to reduce the costs that makes this accessible to the average person. For example, perhaps a software algorithm could be used to detect patterns from a combination of VOC and particulate data that would allow for fewer or cheaper sensors.

    Any feedback or suggestions are greatly appreciated! Thank you.

    50 Comments
    2024/04/21
    23:40 UTC

    1

    Requesting feedback! I want to create Udemy like courses for my job.

    I’ve worked as a factory engineer most of my career. My new job is with a design company and it’s a dream. It’s 100% behind a desk. It’s the kind of work where it takes a few years of on the job studying and research to get your feet under you. Having a continuous improvement background I’m still always looking for that big win. However - my current role there are none.

    It dawned on me the other day that it would be incredibly helpful if there were Udemy like courses that were curtailed specifically to my role. For example- weeks leading up to and during the first month on the job - I completed a “Pump Design” udemy course and it was a life saver!! I think I could do that for some of the other more prominent spreadsheets/calcs that we perform at work.

    In the same vain - a large part of my role is marking up drawings of vessels and PIDs. I was thinking to create a mark up “test”. To this day I’m still getting feedback on nuances I missed or learning in general. I would have been much more valuable to the company if there was a guide/test I could have completed. It would have been a set of dwgs that I would go through and then the answer sheet provided explaining all the mark ups and reasons behind them.

    I hope I explained enough to get some feedback from you guys. This work is pretty intended and I didn’t want to create a mega post and lose the audience.

    2 Comments
    2024/04/21
    17:36 UTC

    24

    Building a replica of Tesla's radio-controlled boat

    6 Comments
    2024/04/20
    18:08 UTC

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