Farry > wrote in message >. ..
> "Dave Gibson" > wrote:
>
> >The kitchen scales use strain guages as the weight transducer. Although
> >these are not linear in output (which is compensated), they do not exhibit
> >the fault you describe. Its more likely to be a fault in the weighing
> >platform suspension mechanism sticking (imagine a shaft going through a hole
> >and rubbing on the side). Probably a batch manufacturing problem. Check the
> >batch number of your model and take it back for exchange, making sure the
> >new one is from a different batch/manufacture date.
>
> Unfortunately, there's no batch number, the model number is the same,
> and the appearance of the old and new scales are identical, as far as I
> can remember. I believe that I've eliminated the possibility of the
> mechanism sticking mechanically, so that leaves either a bizarre
> electronic fault, or more likely in my opinion, an ill-thought attempt
> to compensate for drift in the strain gauge.

Jumping in late here, I think if you go back and look at the data you
posted from your experiment, all you've really shown is that you get
different results if the weight is added suddenly (whether bowl or
muesli) or gradually. By far the easiest and most likely explanation
of this is friction: there's something "sticky" in the mechanics
between bowl and strain gauge and the friction is not overcome when
weight is added very slowly. I may have used different words but in
effect, I'm with Dave here.

- Mark W.