Re: Plastic snaps versus good quality hardware

[Mathew Pelletier <mathew@redhorsetech.com>]

> 
> BioThane tack for example, should be made with a given breakpoint and
> breaking-stress in mind. Because the belting has a breaking stress 
> of 1000 lbs per square inch,you *want* something to give, without losing 
> control of the horse. I have several calculated breakpoints:
> 
> 1. Throatlatch: I have chosen a lightweight snap at the throatlatch, 
> which can easily be replaced.
> It took some searching to find a brass snap with a brass tongue (stainless
> never holds up) lightweight, yet sturdy. Modular design allows easy replacement.
> 

-=-=-=-=-=-=-=-=-=-=-

First point... I'm not pickin' on anyone (see, lotsa smiley faces :-) 
:-)  :-)); I know that sometimes our posts to Ridecamp make us appear to
have other intentions than we, well, intended.  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.

As far as the properties of these two materials, quality stainless steel
tends to have a higher tension yield point (35,000 psi) on the average
compared to many different types of brass --- for example, red brass
(15% zinc, annealed) has a tension yield point of about 10,000 psi,
while the same material that has been hardened has a much higher value
of around 57,000 psi (although the elongation values are less).  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!).  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.

I've had many brass "horse bridle" buckles break, and the same for that
cheap flaking-off-imitation-of-stainless-steel chrome-type stuff, but
have yet to bust a true stainless steel buckle, size for size.  Guess
you get what you pay for (makes tack expensive real quick ;-)). 
However, I am glad you have found good quality brass hardware that holds
up for your biothane tack.

Back to work (and away from the Properties of Materials books),

Kim (and give-me-cheap-buckles-and-see-how-fast-I-can-run-home, Lee)