Since we light buildings with 60 cycle flourescent lights, we are actually being strobed 60 times a second and in the dark 60 times a second.

I have a doorway 8ft high by 3ft wide and I rig it so a 2" metal bar drops from ceiling to floor spanning the doorway on a chain drive in the walls. Then the bar returns up behind as another drops in front connected to the same chain.

With 24ft of chain in the loop and about a 1000 rpm motor and gearing I could have the bars drop from ceiling to floor in less than 120th of a second. I could time it so the bar only dropped in between strobes.

Wouldn't an observer see an empty doorway but experience an invisible wall of steel?

Just aman

He'd get his hand sliced off is what would happen.

What if the bar was tipped leading edge away and maybe rubber rollers on the top near edge? Then maybe it would just hurt really bad. I see it would be easy to make it lethal but hard to design it benign.

Just aman

wouldn`t synchronising the phase be a pain in the butt tho, not to mention the sound?

Synchronising is pretty simple since the motor would be on the same 60 cycle power so it shouldn't drift out of phase. Kind of like a table saw blade under flourescent lights, you can't tell if it's spinning except for the sound.

The sound could probably be minimized below the noise level of a common escalator because the motor and gearing would be even more remote. Piece of cake.

Just aman

so again, why is someone trying to go through what appears to be a metal wall? especially if there's a slight humming noise???

 

but that'd be pretty cool

The bars are only in the passage between strobes so you wouldnt see a thing. It could be synchronized to look like a solid wall if you wanted to by shortening the chain and changing the phase. Our eyes are pretty inefficient and easily fooled.

Just aman.

oh yeah I see what you're saying. Right on then.

moving metal bars at those types of speed would cause alot of vibration and stresses in door frame and the chain, I have a feeling it would rip itself apart, and since there`s no way to center/ballance something that has linear momentum, the changes in direction from up to down in 120`th of a sec would be quite noisey.

maybe I`m not picturing it correctly though?

That seems kind of like fooling video cameras by moving in between frames....

I would just put a steel door there. I think the rattling chains and whooshing bit of metal zipping up and down 60 times per second would be pretty noisy.

I'd use a Rancor.

 

It's not really applying engineering, but it works anyway.

It seems to me that would lose a bit off your knuckles or the tip of a finger it you tried to put your hand through this. Depending on the surface and edge of the material you used. For audio reasons I would think you would want a smooth surface and sharp edges.

 

Since we're dealing with a rather large surface for the "closed door" (say 8'x4') that is for the sake of argument maintaining whatever its movement speed is, as well as position relative to whatever wants to go "through" it. You would be stopped from moving through the doorway entirely while it is "closed" Is there a friction issue here?

 

If you ignored the pain and attempted to put your arm through this, would you be stopped, sliced, or friction-ed into submission?

 

-Jake

The idea was sparked by a wild hair that said we have very historic things that need to be available to the public viewing but not be inside a giant bullet proof container now that terrorism has threatened the things that would give people sufffering at their loss.

We don't have force fields yet, that I know of, but I envisioned a few blades on a loop of chains over a top and bottom drum gear and maybe they could use a speaker system with anti-noise to deaden any sound. A synchronized strobe would give a clear view of the object yet it would be perfecly safe.

Just aman

how about thick bulletproof, bombproof glass and a well designed vault, like they store the crown jewels in?

What if they want to protect the Pieta or Lincoln Memorial statue of Lincoln or something else as big? It sucks having a lot of plastic in front of it and see it sitting in a big box. I want to see one on one, but I also want them to be safe.

Just aman

You speak craziness, earth boy.

 

The thing you suggest will scale up much more poorly (and expensively) than glass.

What about this:

 

1 large cylinder(room sized) with a door sized entry/exit

 

1 slightly larger cylinder with "doorways" cut out, spaced by the same "doorway" sized solid areas. Wrap this around the first cylinder. The You could then spin the outer cylnder at a speed so that 60 times per second the "doorways" match up.

 

You could also put a third slightly larger cylinder on the outside. with a doorway to match the inner cylinder.

 

Assuming you had something like this working, Does anyone have any thoughts on what would happen to you if you attempted to go through the doorway?

 

-Jake

Sliced and diced.

I know it would be an expensive exercise but my interest is engineering a way to tackle a problem with existing technology. I love building crap or picturing that it could be built. The glass has to go. What other solutions until we have a EM+ force shield is an option other than something lethal? A rounded surface of blades, maybe with rollers would be a safe obstacle but other things like strobe lasers would be expensive and harmfull.

 

Just aman

Jake said in post #18 :

stuff

 

this is roughly the process that food processors and carrot slicers use.

How about those Pulsed CO2 Lasers, the sort they use in plastic surgery and the like, they`ll take your skin off in micro seconds. if something like that were set on a sweep patern (a bit like the laser spirit levels used in building), I`m sure it would be just as effective, with the added advantage of being portable, perfectly invisible, silent, and the power levels could be preset to whatever effect you wished, it would also keep flies and mosquitoes away

How about a "no trespassing" sign?

 

Or, if you dont trust your fellow human being (which i dont and you shouldnt), and put one of these type thingys into operation to protect something, well, you'd have to display that something in a place that gets no sunlight whatsoever............only artificial light. And art always looks better in sunlight. Always. That thar's why the louvre is full-o-winows, they even had one specially built to cast a warm glow on the Mona Lisa, if my best friend's memory serves me right...

I thought they didn't like sunlight in art galleries, because it fades all the pictures.

It does. But they have restorative things and UV blocker screens that keep it from happening, right?