General question about metal strength

Jason Gurtz jason at tommyk.com
Wed Feb 22 22:49:19 PST 2006


On 2/22/2006 01:18, Robert Connolly wrote:
> Hello. I'm wondering if any of you can suggest a metal, or composite, for the 
> ultimate mining/masonry work boot...

Two that come to mind are Magnesium and Beryllium.  One bad thing about
Mg is that it's prone to oxidation so it would need some kind of surface
treatment to prevent that.  It's pretty expensive, extremely difficult
to weld, difficult to machine, but is very strong and also ductile.  The
web says it's often alloyed with Aluminum.

Beryllium is an amazing substance. Be is element 4 and thus is extremely
light weight per volume.  It is stronger and more ductile then steel.
It is highly resistant to oxidation and has a very high melting point.
Not too many people have enough money to buy it, yet alone have the
capability to work it.  Now the bad.  It is rather toxic and difficult
to find.  People will be suspicious if you ask about getting quantities
of it.  Much of it is used in nuclear weapons and has become
radioactive.   You can read more about it on the web.  Some things you
might not find that I've learned from a friend who's worked at certain
government agencies that deal with it.  It must be machined with diamond
bits because it is abrasive.  It also has a tendency to tear rather than
cut cleanly on machining equipment so it is a slow, arduous and
expensive process for a skilled person to make a precision anything out
of it.

I think reality says your problem is better solved by re-engineering the
boot.  Something like this crude drawing (looking head on at the toes):


     ( )  <--- Steel or aircraft Al tubing (maybe 20mm diameter or so)
   //   \\
  //0OOOo\\
      ^
       \
         Toes

Basically, form some kind of tubular cage around the forefoot.  The idea
also is to make the shape so that it's more likely that the heavy object
ends up dealing a glancing, rather than a crushing blow.  Maybe you
could start with a crampon frame and weld strong tubing to it.

You could also experiment with making molded laminations out of epoxy
and carbon or carbon/kevlar composite cloth.  Check out
<http://www.fiberglasssupply.com>  I've had good luck with MAS Resin
which you can get from defender marine supply

~Jason

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