Breaking stresses and snap quality

[Dominique Freeman <fadjurs@sadandy.hpl.hp.com>]

Hi Kim,
Nothing like a good scientific debate, backed by knowledge and numbers!

 > But, I'm kinda confused
> with the "stainless never holds up" part of the post.  Are you referring
> to these buckles breaking, or ???  It's been my experience that
> stainless buckles tend to hold up to horsey-yanks-and-pulls better than
> the available brass buckles of the same dimensions.

One of the difficulties here (and you allude to it later in your post)
is that most people have a hard time telling the difference between
"good stainless" and "pot" metal, or zinc alloys. So pound for pound
no disagreement with the yield point of brass versus steel. The average
"stainless" hardware (term loosly used to include all of the above)
doesn't match the yeild point of pure stainless. In fact alot of
the stuff sold as stainless does peel, (and rust!!!).

>  I won't
> get into impact tolerance, fatigue, etc. as I am just assuming that
> these buckles are breaking while the material is under extreme tension
> (horse caught and pulling, etc.), that the force is not great enough to
> apply fatigue considerations (ie the buckle is big enough for the job at
> hand), and that the horse isn't hitting this thing with a hammer (I
> DON'T want to be ridden today 'ma!).

Actually, this is another point in favour of brass, as I have found the
"softer" properties to be beneficial in pull backs where the horse
realizes he has come to the end of the rope, and stops. In fact I have
several loop connectors which are "oval" rather than round now due to slight
distortion, and holding after a "spook" instead of breaking away. 

In addition, those of us who live in coastal zones find it easier to 
clean the brass of a light saline deposit rather than run the risk of 
corrosion on the steel.

> I guess what I'm trying to get
> across is that the *type* of material should not only be considered, but
> the processes that went with it in the manufacturing (cast, annealed,
> hardened)of the buckle.

Cast bronze makes a very good material for halter squares and rings.
I stay away from welded rings and squares (the weld can irritate at
the ears) and only use welded squares now.

the endless search for good hardware is time consuming.......


Dom
(Life is short, the search for perfect hardware is long....)

______________________________________________________________________
Dominique Freeman              |  "Life is short, science is long"   | 
fadjurs@sadandy.hpl.hp.com     |                                     |
Hewlett Packard Laboratories,  |                                     |
Palo Alto, CA USA              |                                     |
Phone: (650) 857-8596          |                                     |
FAX: (650) 857-2862            |                                     |
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