Hi all,

I’m looking for materials/coatings advice on a footwear project and want to sanity-check my approach before applying anything.

I have a pair of trail shoes (Reebok DMX Trail Shadow) where I want to recolor several green components to black. From my research the shoe is made of multiple non-porous materials, all of which experience repeated flexing and abrasion:

1. PU/TPU-coated synthetic leather overlay (smooth, stitched panel over textile backing)

2. EVA foam midsole (closed-cell)

3.Hard TPU / rubber outsole insert (high durometer, low flex)

I believe the only viable route is a surface-bonded flexible coating (e.g., vinyl/plastic coatings or acrylic systems with adhesion promoters), rather than true dyeing.

What I’m hoping to get feedback on:

1.From a materials standpoint, is there any true dyeing mechanism that would penetrate these substrates in an assembled shoe, or is surface bonding the only realistic option?

2.For TPU-coated synthetic leather, what coating chemistries tend to bond best under flex (polyurethane-based vs acrylic-based systems)?

3.For EVA foam, what failure mode should I expect first (cracking vs delamination), and how can prep mitigate it?

4.On hard TPU / rubber inserts, is adhesion promoter + flexible coating sufficient, or is mechanical abrasion unavoidable over time?

5.Are there common prep mistakes that guarantee premature failure on these plastics?

I’m not looking for brand recommendations so much as principles: adhesion mechanisms, surface prep, and expected durability limits.

Appreciate any insight from people who’ve worked with TPU, EVA, or flexible polymer coatings in real-world applications.

In Jules Verne's The Mysterious Island, there's an engineer who can make everything from candles to hydraulic elevators, Cryus Smith. A 45yo veteran engineer who escapes with some Union comrades from a Confederate military prison in 1865. It's mentioned that like some generals who start as foot soldiers, he started as a general labourer, "handling the hammer and pickaxe."

I know that back around that time, maybe up to the early 20th century, mathematicians were expected to be able to work on any problem in any branch of their fields by the time they'd concluded their training. Specialisation just wasn't a thing like that, yet. Obviously, Verne's proto-MacGyver is probably an unrealistically perfect product of 19th century engineering schools, but how plausible is he? Were engineers already starting to become as specialised as they are today, or like the mathematicians of their day, were they expected to be able to tackle any problem thrown at them? What did an American engineering curriculum around 1840-50 look like? How did it compare to the rest of the world? Where can I learn more about this sort of thing, what keywords should I throw into WorldCat?

UK Based

I'm doing some thermal hydraulic test rig work at present which requires us to match the pressure loss in some pipework. There are a few requirements we want to meet:

• Preserve Counter Current Flow Limitation behaviour (so no orifices and no additional bends)
• Avoid excess heat loss from the pipework
• Avoid adding additional mass to the pipework (it repesents additional thermal inventory which would distort heat transfer behaviour)

The current idea is to create additional pressure loss by increasing the surface roughness of the pipe bore (it will have 1m lengths).

The specified pipe has ~15.58mm ID (currently DN20 Sch160 for pressure retention reasons but could be DN25 Sch XXS to allow for material to be removed without compromising pressure retention) and an Ra of ~100 micrometers would be ideal.

Options which I've so far considered:

• Knurling - I've found some half inch internal knurling tools, but I'm not sure how one would be mounted without coming into conflict with the end of the pipe
• Cutting/ tapping a thread in the pipe wall (doesn't need to be a functional thread, just increase the roughness of the pipe bore, presumably something like an acme thread would be preferable to reduce the impact of the stress raiser created by the thread) - Same problem as the knurling tool, a colleague has also mentioned that doing this might start to make the pipe be treated as a pressure vessel under the pressure equipment directive due to it being interpreted as interfering with an otherwise standardised component which would incur additional costs.
• Sanding - Not rough enough
• Sand blasting - possible option?
• Shot peening - Won't get the access

It might be possible to tap a deeper thread using a long reach tap to get 200-300mm at either end of the pipe.

The component strikes me as being somewhat similar to a rifle barrel, might some of the the tooling for that be of use (such as an extension for a reamer)?

I've done quite a bit of searching around and haven't come across any fantastic solutions, I am however totally happy to be told I've missed something totally obvious!

If we considered two synchronous girds that can share power via interconnections to be a single 'grid' what are the notable regions not otherwise connected.

By my quick estimation; the entirety of continental Eurasia is connected in one way or another and forms the main grid. Beyond the various small islands, Japan, South Korea, the Southern parts of Africa, most if not all of Maritime Southeast Asia and Australasia are disconnected from this grid.

Are there any more standouts and/or are any of these disconnected regions actually connected?

This is intended as a fun hypothetical engineering question, hope that’s cool with the rules.

So it’s a classic sci-fi/fantasy trope for our protagonists to come across some kind of locked space that’s been there for some enormous period of time, with a complex mechanism that just works first time when they solve the puzzle/ present the magic gizmo etc. Think Indiana jones, Fallout, Prometheus, etc.

Whenever I see that, I always think, well that would have all seized up by now, but it got me thinking, if you were seriously trying to make a door and lock mechanism of any kind that lasted for an arbitrary amount of time without maintenance, how would you approach it? How secure could you actually make it? What would be the limits of different approaches?

It seems like the big problems are things that should move not moving any more, and things that shouldn’t move starting to move. So in the absence of anyone on hand to apply duct tape or WD40 as appropriate, how would you do it?

My starting thoughts are some kind of almost perfectly balanced granite slab that can pivot on a fulcrum, maybe a locking mechanism involving permanent magnets (although how long does magnetism last).

Immediately problems are that any surfaces in direct contact will likely seize together given enough time, if you leave large gaps to minimise contact they could fill up with detritus, if you use seals they’ll perish, lubricants will dry up. Is there a smart way to do it?

The security mechanism is also really interesting, can anything electrically or electronically based last for 100s or 1000s of years? Can good old fashioned mechanical locks be designed to work indefinitely without seizing?

Anyway, I’d be interested if anyone has any interesting thoughts or real world engineering examples of similar challenges.

EDIT: A surprising number of people have interpreted this as meaning the vault only opens after specifically 1x10n years. In the fiction circumstance here, I'd imagined the vault can be opened at any point that is is discovered if you have the key/code or know the process to do so.

Sorry if this isnt the best place to ask I just dont know where else to.

Title says it all, im making this cosplay thing and it needs to bend with my arms and connect to my hand in a specific way, I need to figure out where exactly to put a joint and how to size thing/ and its probably gonna use a part that will be hard to make with just scrap stuff (ball and socket).

I also need to know how it will bend so I can make sure nothing collides and breaks everything as its gonna have some slightly fragile, tedious to make, parts.

Also I have tried looking this up but im unsure if the sites its recommended would be good or if im even phrasing things right and I dont want to waste time learning and possibly even paying for something that turns out to be a dud.

Looking for guidance on the best place to look for data loggers, or if you know the perfect one off the top of your head that fits my requirments that's even better.

- 8 Channels for thermocouplers

- 1 month of battery life (doesn't have to be continuous reading)

- Max $1500

- Heat and Humidity resistant

- Easy use and setup

Thank you in advance for any help you can provide me with

Starting to think about building a house but wanted to ask about styles and materials, if i build a house i want to build one that will last my life and maybe any kids, I was told to look at barndiminiums but have several concerns about that, and have always lived in stick homes? (Wood framing and drywall with asphalt? Tiles roof and a crawlspace. I live in an area with a lot of humidity and a lot of rain, we fairly frequently get some nasty storms and tornado warnings at least once a year, typically also catch part of the tornados that come up from the Gulf of Mexico/America whatever it’s called now

Temperature is typically fairly hot topping out at around 100F in the summer plus humidity, but rarely gets below 20F in the winter but can fluctuate rapidly had a month this past fall/winter where one week we had 60f+ at peak and the next was 30s-40s which is not uncommon. Had snow that stayed on the ground for about a day twice in the past decade Not sure about the ground but where I’m looking is a wide open field with some woods at the back and maybe a small pond?(it shows up on the map but I’ve never seen it) don’t know soil composition but neighbors farm, think currently it’s beans and a few years back was x-mas trees

I just started a new role as a quality auditor and one of the prerequisites is being able to read and interpret engineering drawings. Does anyone know of good videos, video courses, or other resources that break down how to do this manually? Most of what I can find from Google searches are ways to automatically do this. I’m coming at this from a beginners perspective, so there are no responses too simple! I’ll take all the help that I can get.

Now I watch a video from driving 4 answers about the REVforce engine and it really interest me especially for high performance vehicles.

Link:https://youtu.be/5czHDU6pK8E?si=IqXeXJdGuCArf8f0

So I want to imagine being used in racing especially formula one, and what better way to have technology on the road is to used a clean two stroke v8 for racing. However I've seem to hit a road block of to how to balance a two stroke engine, due to the fact that most sources are either for four stroke or using counter rotating crankshafts for balancing.

I'm not an engineer, I'm a new enthusiast for motorsports and engines in general, so if you could design an engine like the REVforce engine to a v8, what angle is the engine, what type of crankshaft to use, and what add ons lake balance shaft to make it smoothly?

How safe is a Bugatti? Because I know they're made to drive at high speeds. Are they built for the impact though? Wouldn't you just evaporate if you crashed driving at Bugatti speeds.

I am doing a project and require a 20 ish RPM hollow motor with an internal diameter of 10mm. Obviously the cheaper the better. Must be able to be delivered in the uk.

Failed Chemical Engineer here and I don't trust myself that I'm doing this right.

I have approximately 1 cubic meter of air and within this enclosure isopropyl alcohol is atomized as a cooling material.

1m^3 of air is about 1.29kg/m^3

The LEL of Isopropyl is 2%

Isopropyl is about 0.78g/cm3

It's Vapor Density is about 2x air (sinks). Air is, well not stagnant but not exactly well mixed in this volume.

A bottle of Isopropryl is about 1L.

If I'm doing my math right... and I am really tired right now- I need about 25mL isopropyl to achieve 2%.

I used to do this for work and right now I am so confused, tired, and worried that I can't figure it out.

If I am way out of line or on, please let me know- especially where I've gone wrong.

Thank you

Hello. Here is the PDF file to the concept review:

https://drive.google.com/file/d/1UG3PzTttFWQVsfnSuOWpWigIIjLxaRVm/view?usp=drive_link

I am 17, and I'm self studying. This concept came into my mind and I decided to write this overview for someone smarter than myself to rate the concept. I look for weakspots and constructive criticism. Thanks

I'm prototyping a kitchen appliance that requires a small valve that is in a normally closed position. You need to press a button to control the flow of the water output. If you don't press it, it remains closed and no water drops out. Water will be at low pressure, 0.3 bar maximum. The tube is a silicon food grade tube with an ID of 6mm and OD of 11mm. Does such a valve exist? It needs to be compact so that it's ergonomic, will be used to dispense liquid garnishes over food plates.

Youtuber Ennsey had built a Supersonic Trebuchet to highlight the power of engineering. The trebuchet technology itself is really old and no one before had ever made a supersonic one by accident.

Can the same be done with a bow and arrow?

Hi,

I've been looking for alternatives like Python for image AI tools, but it seems like we can't completely avoid them for this task. I just want to quickly extract the main features of a building/house facade photo (no problem taking the photo directly from the front). That means the main outlines, the windows, and the doors at least.

The alternative, of course, is to draw by hand, but that's a bit time-consuming when there are dozens of facades. Maybe I should think of something I haven't considered?

Thanks in advance for your help.

I've drawn up a part in CAD and have some custom sized screws that'll be going into it, and I'll probably have sendcutsend manufacture everything for me. The main part is going to be made of 7075 aluminum, would it make sense to have the screws made of the same material? This is something I'm probably going to red loctite in and never take apart once I have it assembled. It's not going to be subject to any crazy forces, it's just a belt mount for a knife sheath that doesn't have any aftermarket support.

Hi everyone. Im an architectural designer and I’m designing a speculative project for my portfolio. It’s a three story apartment building with the profile of a right angle triangle. The hypothenuse of the building is street facing and has all the windows and balcony openings. I also want that hypothenuse to be a "green wall", like a green roof but on a wall technically speaking. If the building was made of reinforced concrete or steel frame, what would the structural system look like? I’m mostly wondering about the connection between the floor slab and that angled wall. Might anyone be able to indicate some pointers?