>> That's impressive, given that even "real moulded plastic" isn't strong
>> enough to make a gun... They're made out of metal for a reason, after all.
>
> Only if you need to fire more than a few time.

I was going to say something about the heat melting the plastic. But 
really, the biggest problem is surely going to be that the charge will 
smash the plastic to shrapnel, killing whoever fires the gun...

> In our modern society, making things that last is so 19th century!

This makes me sad.

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On 03/05/2014 11:09 AM, Orchid Win7 v1 wrote:
>> In our modern society, making things that last is so 19th century!
>
> This makes me sad.

http://www.bbc.co.uk/news/business-27253103


-- 
Regards
     Stephen

I solemnly promise to kick the next angle, I see.

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On 03/05/2014 11:31 AM, Stephen wrote:
> On 03/05/2014 11:09 AM, Orchid Win7 v1 wrote:
>>> In our modern society, making things that last is so 19th century!
>>
>> This makes me sad.
>
> http://www.bbc.co.uk/news/business-27253103

So many people seem to think that when you buy something, getting the 
lowest possible price is the *only* thing that matters. Which is 
frustrating, because I'd actually prefer to pay more money for a quality 
product. But since that's currently unfashionable, nobody makes those 
anymore. (Or if they do, because so few people buy them, they're 
*severely* expensive. Manufacturing costs have to be split between a 
fewer number of buyers, and all that.) It's not even like buying a more 
expensive model even guarantees better quality anymore; anybody can take 
an inferior item and just slap a bigger price tag on it...

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> I knew there were at least 6 main plastic types.

No, there are two.  Thermosoftening and thermosetting plastics.  Each 
type has thousands of different molecules.


> But 10,000? Really?
 > I can imagine you could have 10,000 different compounds, with different
 > additives in them to adjust how springy or brittle they are, etc. But
 > 10,000 fundamentally different molecules? Really?

Not necessarily.  Take the simplest plastics, such polyethylene, which 
is just chains (called polymers) of ethylene molecules (called 
monomers).  Depending on the length of the chains, you will have 
different properties, hence different commercial applications.  LDPE and 
HDPE behave quite differently.

Also, if you alternate monomers in your chain, you will have different 
properties as well.  Nylon-4,6 behaves differently than Nylon-6,6 or 
Nylon-6,9.

Etc.

 > most plastics melt if you pour boiling water on them, never mind
 > heating them to *hundreds* of degrees...
>

YABAMBA.


to Google, don't you?

> (Also, if this plastic as such a high melting point, how do you mould it
> in the first place??)

You realize the technology to melt metals - which have higher melting 
points than plastics - has existed for millennia.

Also, look into "creep".  You don't need to melt it to be able to shape 
it.  Just like a blacksmith doesn't have to melt iron into a liquid to 
make horseshoes or a sword.

Finally, you *must* have come across pots and pans that have plastic 
handles.  I'm sure these don't melt everytime you boil water.

-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
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/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

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>> Second, you worked in the chemical industry for over 10 years. I'm sure
>> you're familiar with the names 3M, Dupont and BASF, just to name those.
>> Don't think for a second that these companies don't have large R&D depts
>> that work round the clock trying to come up with newer compounds
>
> I was under the impression that 3M's main business is *manufacturing*
> plastics, not designing new ones. (Actually, I was under the impression
> that 3M manufactures finished products that have plastic _in_ them, but
> I guess they probably sell raw plastic to other people...)
>
>> Have you noticed how nowadays most eye glasses are made of plastic?
>> Clear plastics with higher IOR (sorry for getting slightly on-topic for
>> P.O-T) than glass were unheard of 30 years ago. The progresses made in
>> the domain of contact lenses is even more impressive than that of
>> conventional glass lenses.
>
> Really? I thought *all* transparent materials have an IOR different than
> air. As in, it's impossible to *avoid* this (e.g., if you wanted to make
> a kind of "invisible glass", you can't do it.)
>

Where did air come from.  I mentioned GLASS?

>> The "technical" garment industry has also greatly benefited from these
>> new polymers. You're a skier, so you've most certainly seen the
>> 74732327523 tags that are sewn or attached on a new ski jacket or
>> gloves, touting the amazing breathability, yet still impermeable,
>> feather light, yet warm as a mammoth pelt, machine washable, yet won't
>> fade properties these clothes now offer.
>
> I thought that all of those claims were radically exaggerated marketing,
> and that these materials are basically identical to what we had 40 years
> ago.

Then you thought wrong.  Even if the marketing does tend to overstate 
their capabilities a bit.

-- 
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/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

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> On 1-5-2014 22:38, Doctor John wrote:

>> YABAMBA
>
> not sure what that acronym means but if it means something like GIYF or
> 'why don't you just think before you post' or 'have you heard of the
> concept of newspapers and magazines', I agree.
>

Look earlier in the thread.  It means 
Yet-Another-Bogus-Assumption-Made-By-Andy.



-- 
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On Fri, 02 May 2014 16:31:42 +0200, andrel wrote:

> On 2-5-2014 15:49, Doctor John wrote:
>> On 02/05/2014 11:53, andrel wrote:
>>>> YABAMBA
>>>
>>> not sure what that acronym means but if it means something like GIYF
>>> or 'why don't you just think before you post' or 'have you heard of
>>> the concept of newspapers and magazines', I agree.
>>
>> Yet Another Bogus Assumption Made By Andy
>>
>>
> yep, that sort of covers it.
> 
> I fear that this could become an often used acronym in this group.

I don't know that I fear that, myself.  I can see its utility in 
discussion - a time saving device. ;)

Jim



-- 
"I learned long ago, never to wrestle with a pig. You get dirty, and 
besides, the pig likes it." - George Bernard Shaw

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On Wed, 30 Apr 2014 05:30:12 -0500, Tim Cook wrote:

> On 2014-04-24 14:32, Francois Labreque wrote:
>> Andy has also assured me that iPads, Kindles, Nooks, and the various
>> android-based thingamajigs weren't tablets at all, because tablets were
>> 2 inch thick laptops that weigh 20lbs and on which you write with a
>> Palm-Pilot stylus.
> 
> Hear, hear!  Well, augmenting the specifications a little, but I concur
> that these newfangled touch-only widgets aren't REAL tablets...my
> current dream machine is the Fujitsu Stylistic Q584.  2560x1600 screen,
> 10.1"x7.12"x0.39" with proper Wacom pen input, weighs 1.4 lbs.

But surely that's impossible.  Or hideously expensive.  Quite possibly 
both at the same time. ;)

> ...oh, and it has loads of other bells and whistles, if you're into
> those things.  But dat display...over four times the resolution of my
> Fujitsu Lifebook (which, at six years old, is rather closer to your
> referred attributes, ahem), in a smaller area.  And it's less than a
> thousand dollars!
> 
> Mind, the Q584's specs are rather unusual and extravagant; most
> pen-input tablets are still poking around the 1280x800 neighbourhood.

In all seriousness, that sounds like a pretty nice piece of kit.

> Also, re. OP:  It's the future.  I was promised flying cars!  But I
> don't see any.  Why?  WHY?

Have you seen how people drive? Do you REALLY want that in 3D? ;)

Jim



-- 
"I learned long ago, never to wrestle with a pig. You get dirty, and 
besides, the pig likes it." - George Bernard Shaw

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> Given that a 3D prototype will be made of a totally different material
> with totally different properties, I'm not sure how having a prototype
> lets you check this.

As I said, the materials used for 3D prototypes are designed to mimic 
real plastics. The properties are very similar (especially for stiffness).

>> FWIW I've *never* seen tooling get
>> made exactly right first time, there is *always* something that needs to
>> be fixed or changed
>
> Really? I find that quite surprising. (Then again, I don't work in this
> industry.) I had assumed that by now, making something trivial like a
> cube-shaped box would be easy.

Surprisingly something simple like a cube shaped box is problematic for 
a variety of reasons. The sides are large, flat and almost perpendicular 
to base (or at least you want them to be). This makes it much more 
likely the part gets stuck in the tool, parts stuck in tools = $$$. 
Plastic shrinks as it cools, large flat surfaces = twisted and warped 
parts. Usually you would put supporting ribs on the inside, but in a box 
I guess you want to actually use the space inside for storing things, so 
you are a bit limited what you can do.

> That's impressive, given that even "real moulded plastic" isn't strong
> enough to make a gun... They're made out of metal for a reason, after all.

Well it's clearly strong enough to fire at least a few rounds (there's a 
video on youtube I think). And if you're the sort of person who wants to 
try and get a gun through some security checkpoint then you probably 
don't mind that it won't be a long lasting reliable weapon.

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On 06/05/2014 04:46, Jim Henderson wrote:
>> >Also, re. OP:  It's the future.  I was promised flying cars!  But I
>> >don't see any.  Why?  WHY?
> Have you seen how people drive? Do you REALLY want that in 3D?;)

I certainly don't. Too many idiots on the roads if they took to the 
skies I would take to my bed. Even then you never know who might drop in 
for tea. ;-)

I have been reading a lot of ancient SF recently. The thing that almost 
everyone got wrong is mobile phones. It is jarring when the hero has to 
stop by a drug store just to phone someone.

-- 
Regards
     Stephen

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