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Ask HN: What's the coolest physical thing you've made?

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671–680 of 694 posts

Re: Ask HN: What's the coolest physical thing you've made?

#671

I made a baseball bat that uses explosives to add a bunch of energy to your swing and hit a baseball really far. It uses the explosive blanks normally used to shoot nails into concrete (e.g. ramset). It worked way better than I expected, didn't have a kick, and turned out to be just a really neat thing to look at while sipping a frosty beverage. I also made a video about it if you're interested: https://youtu.be/Puo6…

Oh hey I made a jigsaw your robot can't solve

Re: Ask HN: What's the coolest physical thing you've made?

#672
post #357

Earlier quoted context omitted.

I know that fire pits (and outdoor stoves) need high heat mortar ... did you use that here or is the heat level low enough that it's not necessary.

You don't need high heat (refractory) mortar for many outdoor fire pits or stoves. It's mandated in many places (and for good reason) for indoor fireplaces, chimneys etc. That's because regular mortar will crack when subjected to roaring fires, and you don't want the heat, fumes or fire itself to escape the chimney. But e.g. for a fire pit it's usually no big deal, as the outside of the pit is presumably soil, or the…

This is true at all. Explosive spalling is a very real thing and you can see many examples of this online. Cracking is a minor manifestation but it can be much more violent.

https://www.youtube.com/watch?v=vV0saM5IFwE

https://www.youtube.com/watch?v=NxJPX0lssIQ

Re: Ask HN: What's the coolest physical thing you've made?

#673

Earlier quoted context omitted.

It depends greatly on where you are. I LOVE airplanes and being in the air, and everything at all to do with aviation, so I once entertained the idea of getting a PPL. I called around to the various local airports and clubs to get an idea of what was involved. Although I could technically afford it, the price tag was eye-wateringly expensive for what would realistically amount to an expensive and non-trivially danger…

> I took up an interest in motorcycles instead. Can you expand on this? I am a motorcyclist with an interest in flying and based on my idea of what flying involves (at least in not very busy areas) it seems a lot more chill and probably less dangerous than motorcycling. Multiple people try to kill me every day the mental load involved in managing all the hazards is quite high.

When riding, the only number you _really_ need to pay attention to constantly is your speed, and that's just to avoid getting pulled over. Everything else can be operated by feel, sound, and judgement. Energy management is easy: if you want to go fast, twist the throttle. If you need to slow down, apply the brakes. You also have to learn to ride defensively against other road users but that comes down to vigilance, general situational awareness, and experience. There's no numbers or math involved per se.

Flying VFR is probably similar in a lot of ways. You have lots of visual references to go by and with experience can tell if you're on the right heading, too high, too low, too fast, etc. This is why I haven't ruled out buying an ultralight some day when I'm retired.

But in lots of cases, and especially when flying IFR, you have to juggle a lot of things all at once just to keep from dying. A GA aircraft might have dozen gauges and those are only the most immediately important things to worry about. Altitude, heading, air speed, engine RPMs, hours of fuel, ATC frequencies, etc. Many flight parameters have a current value, but most also have safe minimum and safe maximum values which change dramatically depending on the phase of flight.

Lots of people have the ability to mentally manage all the parameters of the airplane itself and its position in the sky, and also be able to do it consistently and safely. But my brain just doesn't work like that. I have trouble holding one or two numbers in my head for more than a minute. It would be incredibly stressful if I had to hold dozens of them in my head at once and my LIFE depended on not forgetting or accidentally swapping them around. I know my limits and for better or worse, this is one of them.

Re: Ask HN: What's the coolest physical thing you've made?

#674
post #613
post #591

Earlier quoted context omitted.

I own 4.2 acres in the Sierras north of US-50 between Kyburz and South Lake Tahoe at 5,600ft elevation. It was not easy to find, but there is a seasonal creek that runs through it fed by snowmelt. I had to drill a well 600ft down to find water year round, there are no utilities so I had to dig out for septic, get propane storage for generator power, and I have a gravel path via an easement into an adjacent property t…

How odd, you dredged up a memory of people finding stairs: https://travelermagazine.net/stairs-in-the-woods/

Is this a ChatCPT written article to sell stuff or for SEO purposes? Definitely seems like it, and actually makes me wonder about the entire parent post.

Re: Ask HN: What's the coolest physical thing you've made?

#675
post #310

Built a two-seat, single engine airplane. Took 6.5 years to build and I've been flying it for close to a year now. The U.S. and several other countries have fairly liberal rules allowing for home-built aircraft, so there are actually tens of thousands of home-built planes flying around today. Yes, it's built from a kit (mostly sheet aluminum and rivets, some fiberglass) but I'm OK with calling it cool.

Working on my own RV-8. There are dozens of us! Also, support the EAA! They're basically the EFF/FSF of aviation, AOPA/NBAA/ALPA etc are all shitty industry groups that want to make aviation as inaccessible to the ordinary person as possible.

It’s even worse, general and experimental aviation is hated by the FAA itself. They would rather only commercial aircraft exist so they don’t have to deal with the silly people with their toy planes. The fact that all classes of medical certificates have mostly the same requirements for both general aviation and airline transport pilots (no prescriptions outside of the dozen they are okay with, among other things) shows that the FAA sees genav as just a pathway to get to ATP. I guess the 1500 hour rule indirectly keeps hobbyist pilots flying.

Re: Ask HN: What's the coolest physical thing you've made?

#676
I've drilled a hole in a fridge to put inside temperature and humidity probes, a fan, and a dehumidifier to turn it into a meat curing chamber.

EDIT: if you're in London and you want it, I'm giving it away as I'm moving to a smaller flat. Just message me and come pick it up.

Re: Ask HN: What's the coolest physical thing you've made?

#677

I made a baseball bat that uses explosives to add a bunch of energy to your swing and hit a baseball really far. It uses the explosive blanks normally used to shoot nails into concrete (e.g. ramset). It worked way better than I expected, didn't have a kick, and turned out to be just a really neat thing to look at while sipping a frosty beverage. I also made a video about it if you're interested: https://youtu.be/Puo6…

LOVE your videos, looking forward to the next one

Re: Ask HN: What's the coolest physical thing you've made?

#679

I made a baseball bat that uses explosives to add a bunch of energy to your swing and hit a baseball really far. It uses the explosive blanks normally used to shoot nails into concrete (e.g. ramset). It worked way better than I expected, didn't have a kick, and turned out to be just a really neat thing to look at while sipping a frosty beverage. I also made a video about it if you're interested: https://youtu.be/Puo6…

Just wanted to add - I absolutely love watching your videos, thanks so much for all of the effort you put in !

Re: Ask HN: What's the coolest physical thing you've made?

#680

I was at an alternative/private school, and while lots of it sucked, they did value doing things with your hands, so something I made were: * a bowl made out of copper, with a fitting lid * a three-legged stool * a very fine pair of salad servers, plus a wooden letter opener * my own apron (sewn on a mechanical sewing machine) * a bowl made out of cherry tree If you count perishable items, probably my semolina souffl…

What sucked about the school?

* high variance in teacher quality (we had such a bad French teacher that after 9 years of lessons, I knew less than those who had 4 years at a public school)

* long hours

* since the school didn't believe in failing students, everybody was kept in class, and the teachers had to do lots of repetitions to accommodate unmotivated students who remembered nothing from the past two years of classes. Very boring and demotivating for others.

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