Call for Engineers: Tell us about your job! (2020)

Me and a friend of mine just got into an argument as to whether amphibious infrastructure is worth investing into. I think it is and he doesn't. We agree on the problems but I don't believe that the solutions to these problems are the impossible feats that he thinks that they are. What do you think? If mods feel this should be taken to a different sub, please let me know. Thank you. I chose the General tag because I wasn't completely sure if this was civil engineering or not.

I'm currently working on a project for a client who needs custom trays to hold HDD components. The trays are made of 4041 aluminum, ESD acetal, and ESD UHMW. The design is a rectangular aluminum plate with ESD UHMW strips glued on top, where the HDD components will directly contact the UHMW.

The challenge we're facing is in finding the right adhesive to bond the ESD UHMW to the aluminum. The client specified an ESD glue because they want the surface resistivity between the aluminum, glue, and ESD UHMW to be between 10^6 and 10^11 ohms. However, they don’t have a specific product in mind—just the end goal of meeting that resistivity range.

Since the aluminum is already conductive and the UHMW itself has ESD properties, I feel like a ESD-specific glue might be overkill. However, I’m having a hard time finding an adhesive that’s strong enough to bond aluminum and UHMW while also meeting the ESD requirements.

Has anyone tackled a similar issue? Do you have any recommendations for adhesives that could work in this scenario?

Hoping someone here can help. I'm looking for a kit for an 8 year old to build something with an engine/motor that isn't a vehicle. Any suggestions..? Or is there a gap in the market?

Edit: wow so many fantastic suggestions... I'll be investigating for a while it seems, especially to ensure it's child directed as I have no skills in this area!

Anyone design or work on meat/food grinders? I like to grind frozen fruit and the last grinder I used was a consumer mixer attachment and the tip of the auger sheared off after multiple uses.

Researching more professional options, none are rated for wholly frozen food. Is there a different tool I should be looking for? The only models I see that are made for “frozen block” are breakers and are 400kg+ industrial machines. It seems to me with an appropriate auger design it should be feasible.

I toured a Lego mini factory and was shown where their extruders used augers in such a way that the compression force was enough to melt ABS all by itself. Leaves me wondering.

I got the question for a movie (sorry). In the ten thousand leagues under the sea, one of the weapons captain nemo had was an electrical discharge he could release through the hull to shock whomever was touching the ships surface.

He used it on a bunch of hostile islanders and a giant squid that was attacking the nautilus. I know that seawater can certainly conduct electricity, but I'm not sure how that changes the usage of electricity as a close range weapon. And I know that there are electric eels that work in freshwater, so electricity shouldn't be completely useless. But is it still an efficient usage of electricity?

I know that jules verne was writing about electricity when it was seen as some incredible, magic thing, so after 100 years how does his science hold up?

Hello,

I am installing a DF ventilation system in my attic. As it is not insulated, I will have to insulate my pipes with glass wool since temperature can drop down to -10°C in winter season.

I would like to determine insulation thickness to limit heat losses and prevent condensation.

Here are my data:

• Lowest air flow rate: 60 m3/h
• Room temp: 22°C
• Ambiant temp: -10°C
• Extreme moisture rate: 80% (condensation temp should be around 18°C for this rate at 22°C I believe)
• Wool thermal conductivity: 0,04 W/m.K
• Wool possible thicknesses: 100 / 150 / 200 mm
• Pipe diameter: 200 PVC
• Max length: 20 m

I have found different formulas online that give different results, so it would be great if I could have your take on it!

Thank you very much

I recently gave “refining in nontechnical language” by William L. Leffler and I loved how easy to follow the complex topics. Good high level book.

What are some introduction books to your industry that are a good nontechnical read to better understand your field?

Working on a project intended for the outdoors, and need to protect the circuits I built. This will be installed under a roof overhang, and so will be protected from direct rain though may be occasionally hit by water droplets blown by the wind. My main goal is to have the electronics mostly environment-sealed, to prevent condensation on them when there is a dew and block any stray raindrops.

My question is: is a 3D printed case good enough for this purpose (assume PLA, 0.4mm nozzle, the infill can be anything you recommend, and the individual parts of the case are sealed with rubber rings)?

I am aware that 3D prints are somewhat permeable, but are they permeable enough to be an issue?

Thanks in advance for your help, I hope I've picked the right subreddit! Normally, I would be on r/AskElectronics but this isn't strictly-speaking an electronics question, even though it is an electronics project.

Hiya! I'm a 3rd year aerospace engineering student, part of a rocketry society, and I'm doing some research into a CO2 ejection system, I've made a design I'd like to test out, however I don't have an accurate way to measure the force generated by the system, as it's such a rapid release of pressure, one technician didn't recommend using a digital gauge as the frequency wouldn't be fast enough to reliably measure the peak force, he recommended a sort of spring gauge, its a mechanical system that 'records' the absolute maximum force it experiences. I can't remember what component he specifically said so if anyone knows what that would be could you please let me know. Or if you have any other ideas of accurately measuring the force that would also be amazing!

Thanks!

I'm working on a more of a Forensic job right now.

We suspect the contractor installed the incorrect strap ties between the (wood) shear walls on a building.

Conveniently, it seems everyone forgot their cameras during the entire installation because there's zero pictures available from before they put up the drywall.

It's a residential structure, so I'd like to prove it without actually wrecking everyone's drywall.

Kicking out for a GPRS rig is more expensive than Drywall repair. Does anyone here know of a better non-destructive way to see through two layers of drywall to ID these straps?

It's all 2x6's, but double drywall means magnets don't work. Stud finders locate studs AND straps, spoiling the data.

Any ideas?

Hey, I am creating a product for a project that is going to sit on the bed of a pickup, its going to be made from 40 x 40 box section steel and enclose the back (like a truckman cover). I want to make mine telescopic so it can fold down into itself and therefore I will need a larger cross-section beam that it folds into for the four corners. I am just wondering, am I required to follow standards for this and if so which? Realistically I will probably make this as an unfoldable structure but I want to see what I can come up with for a telescopic design first. Things like medical equipment will be held in the back when operational. Thanks for any help. (From UK)

If electrical signals start in the brain and travel to the rest of our bodies, and vice versa, is it reasonable to expect an electrical potential difference across the body? I've been measuring voltages differences across my body and can't figure out if my voltmeter is broken or my body is actually fluctuating in voltage.

Canadian here.

I recently moved into an apartment with three reverse cycle aircon units in the same room - two right next to each other and one on the opposite wall.

With no aircon, ambient temp is about 28c. With one aircon unit set to 21, it's capable of bringing the temp down to about 25.5. This suggests to me that the single aircon unit is maxing out and unable to cool to room to the targeted 21.

From an energy efficiency perspective. Lets say i set the target temp to 25.5, whats the most energy efficient way to reach this temperature? Is it to run multiple units and spread the load, or a single unit maxing out.

I guess what i'm asking is, as a compresses reaches it's maximum load, does it become less efficient due to elements like friction, ect.

Thanks

Edit: Living in Singapore

The floor in my kitchen deflects 1.5 inches over 9 feet. I believe this is due to excess load from the 2nd floor and roof only being supported by the floor joists on the first floor. I plan on putting in a southern yellow pine #2 6x6 beam, supported by adjustable jacks at every 6 feet over a 24 foot span. Here is a library of photos showing the floor layouts and walls of all 3 levels, as well as the span table I found. https://photos.app.goo.gl/5iTtEpxSEMgsZYFQ9

I'd like to know if this is the best way to approach this issue. I do have a full basement that's mostly unfinished.

Hi everyone, I'm currently facing an issue in a continuous production process where we end up producing a significant amount of bad product during the transition between two products. I've studied quality management, statistical process control, and production planning, but this problem seems to be more complex than I expected.

I plan to tackle this problem within a Six Sigma project using the DMAIC model, but I'd appreciate some advice on which specific methodologies or strategies I should explore to reduce the amount of bad product during these transitions. I’m interested in learning about techniques from lean manufacturing, advanced SPC practices, or any other helpful approaches.

Any tips or recommendations would be greatly appreciated! Thanks!

We are doing a Reno and our engineer is telling us we need to verify the footing under our post because of the new beam, by my estimate we are max ( and that's like extreme max) adding less than 500lbs to that point. It's a 30 year old home that seems well built. I don't understand how we are debating on underpinning a footing (finished basement btw) for what sounds like peanuts in weight when it comes to a house.

I want to be enlightened so please speak freely.

Hopefully my fair is ok as i don't see structural.

I don’t trust jackstands because of they’re base is significantly smaller than their height. This applies to other heavy objects as well, but mostly vehicles. I tried training to work on forklifts and I was 100% terrified every time I had to stick my body underneath of them. In a similar fashion, I also did not trust, smooth steel blocks, as I was concerned that they would allow the vehicle to slide across. them.

Edit: thanks everyone still have lots to learn but Ive learned some valuable tips such as using cribbing, redundancy (big fan btw) and chock blocks to reduce my chances of dying from asphyxiation or being crush killed. For me feeling safe involves using tools and techniques that make sense by looking at or feeling it. Just wanted to say thanks to everyone for all tips/stories.

This archive will have enough storage to cover the entirety of human knowledge, probably on the order of pentabytes. It will need to survive the apocalypse and keep this data safe long enough for civilization to rebuild from the ashes and re-develop the technology to retrieve it.

Here's what I have so far:

• It will need to deal with orbital degradation. Probably by scooping up trace gasses and storing them for a corrective jet pulse or something.
• It will need a way to assess and make repairs to radiation shielding, perhaps a colony of nanobots? Those will need to be recharged—which means it will need to manufacture/recycle batteries as the old ones decay.
• Most likely a general AI to manage itself.
• In that time frame, it's almost inevitable there would be a collision with a rock or some other space debris
• Bursts of solar radiation, perhaps it would need a "turtle mode" for when solar storms get too bad?

What am I missing?

[Edit: it just occurs to me that when humans nuke the whole world, maybe some of that fallout is going to shoot out of the atmosphere? Is that something we need to consider?]

I've been trying conduct a static stress analysis on a CAD model and from there set up a topological optimisation simulation however I'm finding problems in the current software I'm using that prevent me from obtaining any results (crashing). Are there any other notable software used for this purpose?

I have been using Ansys and I'm fine with resigning myself to the fact that it might just be that my PC is just not good enough.

Image of CAD Model: https://postimg.cc/ZWZLwGwL

Hello , i looking to make this kind of retractable paper mechanism for a birthday gift : https://www.boracay.fr/147-haute_def/banner-pen-ball.jpg I didn't find any information on the pen parts , i guess it's made of some kind of spring loaded roller ? Couldn't find any specific description or name for these parts. Thanks in advance

Edit : I'm french

Hi people

I work at company and we have a lot of motors (42 type) that we test, the shaft sizes vary from 19-24mm. I’m just wondering if there’s a coupling in the market that has a variable diameter so we wont have to buy at least 5 different sizes.

Sort of analogous to glue which is added to the 2 flat surfaces, welding filler doesn't need to be added, why?

Pretty much the title. I’m sure thermal stresses played a role but I have a hard time imaging it would account for the majority of the difference in pressures. Thanks.

I am looking for a similar experience to Magsafe connectors, but for anything that plugs to my wall outlets. I find constantly connecting and disconnecting devices that share outlets (in my bathroom alone I have an electric toothbrush, a hair blower, and an electric shaver) and I'd really wish it was as easy to disconnect and connect as my Macbook Air's Magsafe adapter. Now, I looked around and can't find a single product for this other than this one made by a product studio in Oregon which is out of stock (also can't find any reviews online so can't tell if it ever shipped).

The idea feels obvious so I'm surprised no one has done it. I don't think there are any laws of physics that would make this impossible? Is it a case of a patent or regulations blocking this?

I'm sure the Magsafe engineers at Apple have thought of this :)

Electrical engineering student here, I was watching electroboom's video on making a high voltage supply and while he's measuring voltage across terminals of his transformer, he mentions that the frequency was 60 khz!!! I thought it might be a mistake, but then later he says it's 70 khz. My knowledge is that frequency is either 50 or 60 hz in power grids. So my question is how can he get such results? And are there any benefits for such high frequencies?

I'm doing some work and have widely varying measurements that are represented as a percent. The values are (a) 26.46 % and (b) 0.32 %. Now, following the standard rules of significant figures, this would be incorrect because (a) has 4 sig figs while (b) has only 2. However, it wouldn't make sense to write (b) as 0.3241 % (four sig figs) because we are not measuring with enough precision to know the value to four decimal points. It also wouldn't make sense to shorten (a) to 27 % because we are measuring with precision to two decimal points and have now cut off useful information for no reason.

So what is correct in this scenario and why would anyone use sig figs rather than decimal places to determine level of precision when reporting measured values? What am I missing here?

Right now, I'm doing my IGCE, and I heard from one of my friends that chemistry will be needed to apply for mechanical engineering. Only science I'm taking is physics, so please let me know if I need to pick an extra science subject to apply for mechanical engineering in university.

Hi r/AskEngineers ,

I was looking into my modifications to my Anycubic i3 Mega S 3D Printer's power supply to make it quieter/improve cooling, and I came across this mod that replaces the metal top panel with this 3D Printed replacement: https://www.thingiverse.com/thing:3306465

I've seen quite a few examples of folks doing this successfully here on Reddit and Youtube, however I'm wondering if this is even safe given that its replacing the enclosed metal and grounded top panel with a plastic one. Is it even safe to open a power supply to make this modification? All of my experience is with 3.3v and 5v circuits, and 12V is new to me.

FWIW the power supply is a 12v 350W that was the OEM one that came with the printer.

Thanks in advance for the help!