On 2009-09-14, Denis G. wrote:
On Sep 14, 9:35*am, "Ed Huntress" wrote:
"Ed Huntress" wrote in message

...







"Denis G." wrote in message
...
On Sep 13, 10:39 pm, The Dougster
wrote:

[ ... ]

Let's say I keep a pint or a quart of Gorilla Glue in the home
refrigerator where it's cold and dry, and I let it stand on the
counter overnight before any day I want to use it, so the temperature
is repeatable. Let's say I can measure volumes to 10 ml or weights to
1 gm, whichever is more appropriate the task. Let's say I scale my
projects to use up as much glue foam as I can make with one precious
drop of water.

[ ... ]

Here's a tougher question:

How would you dispense 1/10 drop of water?

[ ... ]

For U100 syringes used by diabetics, each unit is 10 microliters. *A
drop of water is 50 microliters. *To dispense 1/10th of a drop of
water use a 1/2 unit on a diabetic syringe.

Hey, here's something curious. I just tried this, and got funny little
drops, much smaller than I would get with an eyedropper, for example.

I took a 30-unit syringe, filled it with water, and counted the drops in 5
units. I got 11 drops -- close enough to 10 -- but they were really teeny.
These were drops that would detach themselves and free-fall as I held the
syringe point-down; just ordinary drops.

That's exactly 1/10 the size you're describing -- one drop from this syringe
is 5 microliters. I see from some references online that this is the same
size as a drop of water dispensed from a Pasteur micropipette.

So is the size of the drop that dependent on the opening from which they're
dispensed? This was a 30-guage needle. I'd have to mike it to see the size,
but it's *really* thin.

[ ... ]

You're probably right on the difficulty of dispensing it accurately.
It was only a ballpark method with commonly available tools if you
didn't want the expense of buying a micropipetter. I suppose you
might be able to make your own micropipetter by attaching a dial
caliper to a syringe.

Instead of the dial caliper, set up a frame to hold the syringe,
and use a micrometer thimble assembly to advance the plunger.

To get real accuracy you probably need to
develop the art of dispensing small volumes or just get the right
tools.

Or make the tools.

Enjoy,
DoN.

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