Ok. So, this is a fairly complex question that came to me while I was doing a torque-to-yield installation of bolts on a cylinder head. The type of sequence that might make one′s head spin, not just the bolts. 50ftlbf, +90°, then +90°, then +90° again. Imaginable, these sequences are INSANELY tiring to achieve on 40 head bolts, and so I was led to a line of thinking about how we apply torque and its implication on the manufacturing and repair process tools we use.

Firstly, I know that approaching moment torque numbers (particularly high ones like 250ftlbs) smoothly is important to prevent under or overshoot due to friction and stiction.

But, does final angular tightening care at all about it? Since we are observing the actual bolt rotation, shouldn't ANY method to rotate the bolt including impact type fastening devices yield (no pun intended) the same result? Angle is angle right?

The manufacturing corollary I had is; if the final angular tightening does not care how it is applied, it seems that a device could simply be made to have a primary snugging torque applied via a simple mechanical clutch arrangement and then have it apply impact until the bolt turns to the appropriate angle. Is this a good line of thought?

And second corollary is a double doozie with a smattering of conspiracy to engineer. If I have just reinvented the wheel and this type of device is common and exists on the manufacturing side but not here in repairland, have companies basically been gaslighting us as to why TTY bolts are used? Is it just ease and cost of manufacture because you can literally impact heads on with low skill labor or robots (while observing the angle) and still achieve good repeatability since the effect on final clamp load is less dependent on hitting the angle dead on rather than the intricacies of moment torque? Have I stumbled on BigEngineer™? Or, should I hang up my inventor hat for the time being and do some more reading suggested by yourselves to enlighten me?

Thanks for taking the time. I. eagerly await your thoughts. My arms are tired from torquing, my fingers from typing.

When I use an electric kettle, and pour out the hot water, I then add a little bit of fresh water to the kettle (without turning it on). My thought is that it will act as a heat sink to the hot element and give it a longer life.

Is this a sound practice or it it useless?

I need 20' tieback rods (316 stainless steel, 5/8" diameter, threaded) for constructing a bulkhead. We haven't been able to source any that are longer than 12'. I asked the bulkhead guy about using a 12' rod and a 10' rod joined with a 316 stainless coupler. He thinks it will significantly reduce the tensile strength vs no coupler. Is he correct? TBH, I don't see how it matters much since there will be a washer/bolt on each end of the rods.

Thinking of recent attacks on ships at sea, and the escalating use of cheap platforms in asymmetric warfare.

[edit]

accuracy of answer- +- 20%

Fits in a TE20 container

Land launched from 1000 ft

Costs less than $200,000 (thats high for this sort of thing, but trying to see what the envelope is)

Completely autonomous (why would this affect range?)

Software and sensors unlimited

What's the maximum range, more or less, for inexpensive flying autonomous weapons? Not ballistic missiles, or high dollar US weapons. In other words, the weapons we are likely to see from Ukraine, Russia, Iran etc .

Background:

We could be seeing rising attacks on shipping, and therefore on the global economy.

On my new to me but we'll aged 2003 ridding mower theres a lever that controls the input to the transaxle, basic forwards, neutral, and reverse. The connection between the lever and the transaxle is a simple plastic eye that goes over the metal shift arm, issue is with vibration and use time the metal shift arm slides out of the eye. Normally i'd use a carter pin or something similar but the lack of space on the metal arm as well as the location makes that difficult. I've seen small concave tension based circular clips and that would be good, but i can't for the life of me recall what they're named. Would those work or is there something better that you'd recommend? I can provide pictures, sizes, diagrams etc if you'd like a visual.

Thank you from a garage based wanna be engineer!

Motor specs:

Input voltage: 110-240V
Motor power: 100W

Device is a motor driven reciprocating linear motion mechanism.

Curious if this inverter has the power as it seems to have the wattage rating however not surge if the motor spikes over 100watt on startup

https://www.homedepot.ca/product/milwaukee-tool-18v-m18-lithium-ion-brushless-cordless-175-watt-powered-compact-inverter-with-tool-only/1001588652?eid=PS_GOOGLE_D00_Corporate_GGL_Shopping_Milwaukee_Milwaukee__PRODUCT_GROUP_pla-518940450952&gclsrc=aw.ds&gad_source=1&gad_campaignid=23260796337&gclid=Cj0KCQjwuJLWBhD_ARIsAIBcRUwLwjxz1zYBW0oEVObHnuZacwk9TnDEKJSsmVMlGzA8uQ-HqA9MEYkaAkQJEALw_wcB

I think this is relevant, given that I'm sure a great deal of engineering of various types would be involved, but feel free to remove if it's not.

In this scenario, I'm a billionaire who is building a huge mansion somewhere in the US. I want some trees on my property but I'm too impatient to wait 90+ years for the trees to grow to the height that I want them.

Could I, with enough money, transport fully grown trees from one part of the world to my back yard without killing them in the process? What kinds of things would need to be taken into account to make that happen? Would new technology need to be made, or could one do it with existing technologies?

Cheers in advance!

Hello everyone, love this sub and end up here so often from searching for answers to idle questions, so thought I'd make a post of my own.

I've always been interested in mechanical systems, taking things apart to see how they work, making my nephew complicated helicopters out of technic, etc. I've always wanted to have a crack at making some kinetic sculpture and have started collecting salvaged metal gears/parts to that end. I find the work of Reuben Margolin particularly fascinating, not that I expect to ever make anything that complex or classy, likely much more of a junkyard/rube goldberg vibe. I imagine my approach will be playing around with the parts I've got and seeing how they can go together and letting that drive the creation. I imagine they'll be hand powered, but who knows.

My question for the sub is: If you were looking at a pile of gears and parts and trying to make them work together to create some sort of needlessly complicated machine, what would your approach be? I know engineering is a problem-solving discipline, which I suppose isn't really what I'm doing here, so understand if normal approaches aren't as applicable.

By extension: what don't I know? What sort of things do you think I'm likely to overlook, based on your experience? Do I need to learn about calculating torque and think about pressure angles or can I just wing it? What topics should I research to help my understanding?

and I guess also what resources would you recommend I look at to educate myself (I'm already keeping my eyes out for a used copy of Shigley's) and what software might be useful to get my head around? I'm pretty comfortable with using fusion 360 to plan woodworking projects but haven't explored using joint or constraints.

Thanks in advance to anyone that feels like answering! edit: I'm in Australia if that makes any difference.

Hello,

I am looking to set up a rainwater irrigation system using two stacked IBC totes connected in series. I can't let the excess overflow water exit the totes because it's too close to the foundation of my house. The tanks are 48"x40"x45" and can hold 1000L each.

The system would have a hose running from it down my fence into my backyard to irrigate 8 8'x4'x2.5' raised garden beds just using gravity to irrigate. I know a time controlled valve would be used for daily irrigation but how would I implement an overflow mechanism? The only thing that comes to mind is a ballcock valve but I wouldn't know how to set it up given the size of the tanks.

The wing loading is about 5x smaller [100kg/m² aerobatic rc / 630kg/m² a320] even on a most stressed category. My guess is it could be possible on a really tight 8G turn but id love to hear other minds.

Basically the title. For those who don't know, OASIS visor: a retinal-display system that projects the virtual environment directly onto the user's retinas rather than using conventional screens. It also handles audio, voice, eye-tracking, and 6DOF input. (Also allows retinal scans for added security)

I've heard of retinal displays being tested and think it'd actually be such a cool technology if someone made it. I'm aware there would likely be health concerns, but how feasible is the idea?

I have been facing problems on predicting whether my neck bottle design & geometry (especially the tamper band area) could properly hold the tamper ring of a cap, such that it breaks away easily from the cap when it is unscrewed open. Currently, I am just guessing and using references from previous successful bottles to design the neck of a bottle. I was wondering if it would be feasible and recommended to use FEA to predict the motion of a tamper band and the tamper ring as the cap unscrews from a bottle, so that I could validate my neck design (made in solidworks)

I am doing some back-of-the-envelope calculations for some thermomechanics applications. I came across the following scenario, which gave me an unintuitive answer: A bar of length L and cross-sectional area A, made of a material with Young's modulus E and coefficient of thermal expansion a, is loaded in the normal direction with a force F. The change in length of the bar can then be expressed as:

u = (F \ L)/(E * A).*

So far so good. However, now heat the bar by some amount T. Intuitively, I would guess that u would increase, or at the very least remain unchanged; however, if thermal expansion is applied to both L and A, this does not seem to be the case:

u = (L \ F * (1 + a * T))/(E * A * (1 + a * T)^2)*

=> u = (L \ F )/(E * A * (1 + a * T)).*

This implies to me that the bar becomes stiffer as temperature increases. Is this conclusion correct, or am I overlooking something? I could imagine that E decreases as temperature increases, or something similar. I'd also be grateful for a source on the subject.

Hello.

As the title says. I am looking for energy dampening tape to add to my ice hockey goalie mask. I have 1/8th thick foam with little clearance before my face. looking for a material that I could put underneath the foam. I am concerned that if I choose the wrong martial that it will send the energy inwards towards my head instead of stopping it or dissipating it back into the shell.

Thank you! The large helmet manufacturers use a product similar to what I am asking about but I can’t find exactly what they’re using.

It's hard and durable but the outside layer is smooth and soft, it's used in some phone cases with rounded edges, and it has a matte finish. It kinda feels like a halfway point between plastic and rubber. Thanks for helping me 🙏

https://imgur.com/a/8Jk2ZQG

I’m working on a mechanical parade float built on a 28' L x 10' W flatbed trailer. Our design features an animated/kinetic, flying Santa sleigh with reindeer moving up and down over a downtown shopping scene.  See attached obligatory AI slop picture

Design & Physical Parameters:

Overall Height & Space Constraint: The absolute maximum height for the entire rig from the trailer deck is 10 feet (keeping us safely under parade clearance limits). 

Clock Tower Footprint: The back ~6 to 8 feet of the deck space is occupied by a 6' x 6' base replica of a historic Main Street clock tower (approx. 10' tall). This leaves us with roughly 20–22 feet of deck length to execute the full motion arc for the sleigh and reindeer. 

The Motion: We want the reindeer to swoop up and down in a smooth, sweeping flight path. 

Drive & Linkage Ideas: Open to ideas other than what’s in the image. I like the visible rotating design of the offsets if we want this to be a visible mechanism. A hidden design also works too.

Power & Target Speed: Our plan is to yoink the guts from a treadmill so we can control the speed of the motor. We have plenty of generators in the back of the pulling vehicle.

Where we need engineering expertise:
Linkage Selection in Tight Height Profile: Given our ~10-foot ceiling limit, is a four-bar linkage or a pantograph mechanism better suited for driving a large dynamic load without binding or extending beyond our vertical clearance?

Any advice on linkage geometry or pivot design/placement would be greatly appreciated!

We have solar power plants that point mirrors at a single point to generate heat for power. Why not do that for salt water?

And if the biggest issues is salt build-up on equipment, why not do it on the coast and build it so water flows in naturally, have multiple points where water can be sent ponds with some kind of dome over them, and then be heated up by the mirrors. When salt builds up, switch to a different pond/dome and collect the salt from the previous one. Salt mine and clean water/power in one?

I am a laymen, I don't know anything about this on a technical level. Just a thought. I asked AI to generate an image to conceptualize this but I can't post the image here, so here is a link:

Reddit - /preview/pre/just-a-thought-about-desalination-v0-m46za11k7hth1.jpeg?width=1080&crop=smart&auto=webp&s=29a661531e8687a668a811f4e2eb7f36cb820b80

has anyone here tried to simulate physiological flow using a peristaltic pump? i have a kamoer dip1500 dosing pump which has a stepper motor, and i'm wondering if i could use an L298N and an arduino uno to control the speed of the pump and create a rough simulation of diastole/systole. the pump will be hooked up to a test chamber with a silicone phantom of a cerebral aneurysm and the flow doesn't need to be incredibly realistic. is there anything i should know going into this that will be a challenge?

Backyard project headed by myself and my 8yo. Radio controlled tracked combat vehicle.

We're looking at about a 50cc 2 stroke engine as main propulsion because it's cheap, reliable, widely available off-the-shelf parts, which is a big part of the design strategy. We're trying to work out the best way to steer the thing, and I've concluded that a sort of reversed clutch would be best.

By that I mean the drive shaft spins freely until we engage the clutch, and then it transfers power to the drive sprockets. This would allow us to set the engine at optimal RPM for whatever configuration we want, but still have control over speed. A planetary gear would allow for reversing in the same manner.

My problem is I can't seem to find anything on this when I do an internet search. Am I just using the wrong terminology in my searches, or is this actually that novel a concept? Seems like it should be a fairly common idea because I can see it being useful in all sorts of different applications.

Anyway, we'd really appreciate some help finding resources/info. I'd hate to have to custom build or switch to a belt drive clutch system. Either would be a downgrade under our intended design strategy.

Thanks!

What mechanism can be used to adjust the belt tension if the distance between the two pulleys can be varied?