Utility knife in a zipper-pull


#1

[Read the post]


#2

Nice little toy.
Could the blade be made of beryllium for lower visibility on xray?


#3

Why not just go for a ceramic blade, then?


#4

Brittle. And more radioopaque, if it is not e.g. boron carbide or boron nitride. Alumina, silicon carbide, yttrium-stabilized cubic zirconia, all are rather dense and rather opaque for the xrays.


#5

Sure… Make sure you have a zipper-pull handcuff key, for when they arrest you at the airport, eh.


#6

You wouldn’t honestly let them arrest Shaddack, would you? Everybody should try intervening in arrest attempts, it can be a liberating experience.


#7

The issue of brittleness did occur to me, but how much of a concern would it be with a blade this short?
Also, damn beryllium is hard! Brinell hardness value of 600 vs.120-160 for steel? How expensive would a beryllium blade be to manufacture?

Ceramics as a material have always been mildly fascinating to me*, ever since I heard of someone trying to manufacture ceramic car engines. I should get of my ass and read up more on the subject.

*though, evidently, not fascinating enough to actually read up on them further


#8

Not for kitchen use I hope - beryllium is quite toxic.


#9

I just need one beryllium sphere.


#10

I can’t give you a number; but it would probably not be inexpensive. In addition to being something of a specialty item, and hard enough to be murder on your tools, Berylium is nasty, nasty stuff. Depending on your luck, a single modest exposure to Beryllium dust or compounds can kick off berylliosis, featuring progressive development of granulomas in lungs and sometimes other tissues and increasingly severe pulmonary fibrosis. Treatment is symptomatic only; and it’s as much fun as any of the other ‘slow inexorable decline in lung capacity’ diseases.

Used to kill fluorescent light manufacturing workers, before we switched formulations; still gets the occasional miner, aerospace machinist, or physicist. Ugly way to die. It’s a great pity; because beryllium has some gorgeous properties as a material(and as an alloy with copper); but biocompatibility isn’t one of them(indeed, if memory serves, there are essentially no known biological uses of beryllium or its compounds, even in trace quantities. I don’t know why; but apparently it just doesn’t show up in biological systems.


#11

Not that bad, they are quite worse.

Depending on your genetic makeup. Some people can quite withstand it.

It’s the aerosols. The beryllium particles trigger something like an autoimmune reaction. Does not happen with the ingested ones as they are insoluble enough. No idea about soluble compound toxicity at this moment.

I wouldn’t worry about cutting beryllium. The dry grinding part, where dust of micrometer size is generated, is where I’d take care and probably use a glovebox; these are easy to make, I designed a $50 one on a dare and there will be a design upgrade in next couple months with 3d-printable glove flanges to get rid of the most labor-intensive component. If these things are cheap enough, a stinkiness of chemicals is no more a reason to not work with them. Can also protect your shop from corrosive fumes/aerosols from e.g. etching.

How big? I think UnitedNuclear.com has a small one in stock. But I consider sheets a bit more practical form factor; you need thin flat pieces anyway, whether for xray windows or for neutron generators.


#12

Not a Galaxy Quest fan, apparently.


#13

I missed that one. Not enough experiences in that field. :frowning:


#14

Does this make it all better?


#15

There is said to be genetic variability; but when it comes to slow, progressive, suffocation, I’m really not inclined to press my luck.

Were I looking to get this little item through X-ray screening, I’d be inclined to try making the front and back covers, between which the blade sits, aggressively radio-opaque, and coloring the item to suggest that it’s just a solid metal fob.

If necessary, one could even craft the front and back plates with slightly lower opacity where the blade is, so the total opacity of front+blade+back in that area is identical to that of front+back in non-blade areas.

In that vein, you can get tungsten powder, intended as a filler to give polymers extra heft or make them worthwhile as radiation shielding. Not as dense as the solid stuff; but way less obnoxious to work with. Also, pretty much a boring grey color. It strikes me that, if one were in a mischievous mood, one could mix tungsten powder into a binder(acrylic paint, say) and then color match an ordinary grey paint of negligible X-ray signature. This would allow you to paint x-ray visible silhouettes(if you produce mixtures of the two paints, you can even get a ‘greyscale’ of x-ray opacity) according to your fancy, while ensuring that the article painted just looks like an utterly bland uniformly painted item, textile, bag, garment, etc.

Hours of fun when a couple of Uzis and a big pig-stickin’ knife show up every time the bag goes through the scanner; but proves to be a simple bag, without any suspicious bulges, room for hidden compartments, or other possible hiding places on physical inspection. Then you miss your flight and get placed on all the watch lists, forever; but still.


#16

Beryllium isn’t that bad in solid form. The compounds are rather inert. Getting it in your lungs is a different matter. Like silica, but more so.

When I worked on MRI surgical tools, BeCu was an ideal replacement for steel. Except for two problems:
Be : safe for surgery, but no one want’s to machine the stuff because of dust hazard.
Cu : safe for machining, but mildly toxic to tissue.


#17

Back in the day, some folks made a bike out of Beryllium. I think they made just one of them- and at the time, priced it at something like $25k.


#18

Beryllium isn’t particulary hard. You might be thinking boron. Be is softer than glass. It has a very high modulus of stiffness. For a pure element, it is strong, but there are many stronger common alloys.

http://periodictable.com/Properties/A/MohsHardness.v.html
http://beryllium.eu/about-beryllium-and-beryllium-alloys/properties-of-beryllium/properties-of-pure-beryllium/


#19

You can also use barium sulfate. White, nonmetallic, can be used as a filler for a polymer or a white pigment.

If the top-of-line neutron imaging scanners are used, barium borate is the material of choice too. Also fairly common as filler and pigment. Any combination of heavy and light elements will do, this is just the most (or one of most) convenient one available at industrial scale.

Edit: You could use either as a filler for a white 3d printer filament. Using a dual extruder head with another white filament, 3d structures-within-structures could be produced.

Todo…


#20

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