This Instructable will show you how to craft water balance , from used water bottles.

Step 1: What we will need.

Empty water bottles 2l,1,5l ,scissors,blade,pen,a sheet of paper,graduated jar,colorant,glue,water.
This is a neat idea, building a scale by using the displacement of water.&nbsp; In response to therealgrovemachine, this tells you the weight (in grams) of whatever you place in the inner bottle.<br />
so what the heck does it do??<br />a barometer??<br />
Nice and original idea! But....after checking Archimedes' principle at <a rel="nofollow" href="http://en.wikipedia.org/wiki/Buoyancy">http://en.wikipedia.org/wiki/Buoyancy</a> and a lot of hard thinking, I believe that the scaling method dchall8 proposes is the only correct method. I believe that the shape and material of the inner container determine the scaling. Picture putting the same I'ble apple on a styrofoam disk in the I'ble bottle: I guess that with bara1962's linear scaling, the apple would suddenly almost weigh nothing. Still, with a calibrated scale, it is a project great in its simplicity.<br/>
Rats. My memory is shot. I couldn't remember what a water balance was. At first glance, I thought it was measuring volume. (Instructable anyone?) Step 8 does actually explain it quite well with photos, but I would like to see small paragraph at Step 1 explaining what a water balance is for and why I would want to craft one. Just my wish list. Great Instructable. Very good use of photos.
ooooh!, klever... but you might want to use a smaller inside bottle, then the water would rise faster, meaning an more acurate scal, and you could glue a platform to the inside bottle,
No, a <em>wider</em> inner bottle would create a faster-moving level.<br/>
so, a slighter movement would make the fluid move more, this with less weight, the fluid goes up more, thus it's preciser, its like zooming in on the scale, the differences get bigger, so you can see it better...
if you agree with me, why did you start with saying i'm incorrect(first word:no)
Because you were wrong to say that a <em>smaller</em> inner bottle would increase accuracy. My third word was &quot;wider&quot;.<br/><br/>You had the right concept, but took the wrong route.<br/>
yeah, i made a typo... sorry :-)
You mean a smaller outside? Kitemans right, more surface area with a <em>wider</em> bottle on the inside.<br/>
This is clever. Your scale looks linear. Given the oddball shape of the inner bottle I would not expect it to be linear, especially near zero. I guess I would calibrate the graduated cylinder with a calibrated scale first. But that's just me.
I agree.
This is a very clever idea, well done.

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