Dave Fawthrop > wrote in
:

> On Sun, 25 Jan 2004 13:08:45 GMT, Farry
> > wrote:
>
>| Dave Fawthrop > wrote:
>|
>| >Just reread your original post.
>| >
>| >As both an ex-engineer and a software writer, it still looks like a
>| >mechanical problem, and not a software problem. My guess is that
>| >the platform is dragging, catching or juddering on something.
>| >Mechanical problems sometimes build up slowly, or suddenly appear.
>| >Software problems are either there, or not there, all the time.
>|
>| OK, I've just done this.
>|
>| 1. Place clean mirror on worktop to make a perfectly flat surface.
>|
>| 2. Make sure both sides of scale are clean, and place on mirror.
>|
>| 3. Zero scale.
>|
>| 4. Put cereal bowl on scale - 274g.
>|
>| 5. Add tablespoon (20g) of muesli - 294g.
>|
>| 6. Tip out muesli and put bowl back - 274g.
>|
>| 7. Add same muesli back very slowly over 1 minute - 276g.
>| i.e. it's somehow lost 18g.
>|
>| 8. Tip out muesli and put bowl back - 256g.
>| Still 18g down.
>|
>| 9. Remove bowl - and scale shows "----" (below zero).
>|
>| This is quite repeatable. The scale is accurate and consistent, and
>| does not drift even over several minutes, PROVIDED that the weight
>| changes are swift.
>|
>| QED?
>
> Judder!
> A well known mechanical engineering problem. Often experianced in car
> brakes when the car vibrates when braking.
> Friction varies with position and time, not like they teach you in
> school. I have seen it in lots of things but never in scales.
>
> Take it back and demonstrate the problem, Even a shop assistant should
> understand that it does not work properly. Get a different model,
> it may be a batch problem.
>
> Dave F
>

Not convinced Dave. At least it must be coupled with a software fault
if the bowl showed different weights at different times.

--
Adrian