It could be hysteresis (I love that word) in the system. It may be
accurate, but only aftera certain minimum amount of weight is placed
on the scale.
Try adding a bit of weight to the scale, zero it and weigh things
again. If that doesn't work, make up something that's say .1 gram and
whenever weighing something really light, drop this on the scale
first, then add the thing you want to weight. Don't forget to subtract
the weight.
Marty Sasaki
On Fri, Jan 23, 2009 at 8:32 PM, calgoddard <calgoddard_at_yahoo.com> wrote:
> LeRoy:
>
> I have a relatively expensive Ohaus scale that measures down to
> hundreths of a gram. It cost over $200 when I bought it several years
> ago, but it has a nice big platen for holding rubber or plane parts
> (entire wings) so I have been happy with it. It plugs into AC power
> via a DC power supply.
>
> When I get down to very low weights, I have observed a similar
> situation. E.g. 1/32 spars for a small stab show zero weight
> individually, until you weigh five together, and divide to find their
> individual weight.
>
> Someone told me that these digital scales have strain gauges that are
> very sensitive to static charge on items being weighed. I am not sure
> how that factors in.
>
> I think to measure very low weights you need scales good to 1/1000 of a
> gram. I have a friend with two such scales at his company. They cost
> $2,500 each. These are mostly used in chemistry and pharmacology labs.
>
>
--
Marty Sasaki
Arlington, MA, USA
http://www.martys-simple-things.com/
marty.sasaki_at_gmail.com
Received on Fri Jan 23 2009 - 18:01:30 CET