YES NOPE9 wrote:

> What would be sources of error ? =20
> #1       the scale     I did not use the calibrate function since I was d=
oing ratio-metric comparisons.  Maybe cal would have improved things.
> #2      pressing on the hinge where it was clamped to the book changed th=
e amount measured.  I do not understand this.  I waited for the scale to se=
ttle down and it was still showing a reading as much as 5% off.

My guess would be "stiction" at the hinge. Even using e.g. an Avo8 with=20
its decent pivot points you should tap lightly for the most accurate=20
reading.
Test by pressing at the cup end then releasing - take reading - then=20
lift slightly at cup end and release - see difference in readings.

Difficult to tell from picture but check that the moving part of the=20
hinge is not touching the book spine.

I would try a smaller hinge as simplest next step.

George Smith

--=20
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