[meteorite-list] Scales - Looking for Advice

From: dean bessey <deanbessey_at_meteoritecentral.com>
Date: Sat, 9 Dec 2006 17:07:56 -0800 (PST)
Message-ID: <663136.74421.qm_at_web56102.mail.re3.yahoo.com>

--- Norbert Classen <trifid at timewarp.de> wrote:
>
> Good idea - I will certainly let you and the list
> know. And as soon as I
> have my new scale I will test it as I have quite a
> few samples that have
> been weighed rather precisely on A grade laboratory
> scales. So let's see
> what these "cheaper" portable precision scales can
> do.
>
You will probably find that you will be very close to
the expensive scale and you would likely report back
that it is as good if comparasons is made soon after
you buy it.
The problem with the cheaper scales is that they
slowly degrade and six months later will be slightly
off. It wont be a lot. One or two percent at first
maybe. This is especially true if you move them around
a lot or are in an area where there is a lot of
moisture.
It might not be a problem for meteorites as people
rarely need extreme accuracy. I run into problems when
working with gemstones though.
Another problem is that after a while when the scale
starts giving out the weight will start to vary
between the close weight and not stop at a final
number or you will get a small variation if you weigh
the sample multiple times (This last problem could be
found sometimes in a poor quality new scale).
If your needed accuracy is .1 gram you dont really
have a problem (And the scales are under $100 so not a
major issue if you have to replace it anyway) but I
think you said you had small stuff and you will
encounter these problems when weighing to .2mg
accuracy.
Tanita brand is about as cheap as I would go for mg
accuracy. They are reasonably durable when carying
around also.
Anything cheaper than tanita and you will likley have
a
short life span on the scales.
Some of the really expensive scales dont travel well
and if moved around a lot would need to get calibrated
occasionally so more expensive is not necessarily
better.
Sincerely
DEAN (AMUNRE on ebay)



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Received on Sat 09 Dec 2006 08:07:56 PM PST