Excuse my English.
This is a very inexpensive, simple and easy to make precision scale.
You have to obtain miligram weights to compare in that units.
Or cut small squares of paper and declare that to be your new unit (1cm^2 of paper ~ 7.5mg).
Can compare two weights and tell even only 1mg differences.
With aditional vertical part marked like a ruler to a mg scale it could weigh even directly.
Ingredients:
-1 wooden skewer
-VERY thin, hard to tear string
-a little bit of hard paper
-some legos or an equivalent to make a similar shape to hold the construct.
This is it:
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It is very simple. It begins with the wooden skewer, which is cut a bit on 3 places with same distances from the middle one.
With reef knot there is a thin string secured in the middle cut.
Have the knot on the top on the skewer for negative feedback that is easy and intuitive to work with.
Make dishes of the paper and knot it like on the close-up.
Do it well so it hangs straight. Make two paper "spoons" for loading/reloading.
These two spoons should be the same weight so accidental switching of them wouldn't affect arm positions.
The best shape for these spoons seems to be that brilliant shape you can see on photos. It is easy to grab and take in/out while still having enough space for spice.
The top string should be thin to minimalize random tare disturbing.
With two weighing dishes connected to the other two cuts the core is done.
Now make the outer shell somehow (made of legos in the pic) and attach the middle string.
Now check which side is heavier and cut some wood of the skewer to tare that.
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This is close-up of the main part, the knot from the drawing will ensure right direction of the skewer.
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And this is "the locker". It will lock these arms so one can manipulate with dishes freely.
This scale works very well, just needs no airflow (do not breathe directly at it during weighing) and few seconds to let it stop oscilating and point the answer. 1mg seems to move the pointing end of the arm over 1mm. The scale on the pictures has been giving great results, with an accuracy equvalent of a 0.0005g digital scale.
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