A sensor to weigh very small weights

I would like to build an Ardrino unit to accurately measure small weights, specifically bullet reloading components such as projectiles and gunpowder.

So in the first instance as a learning thing I want to detect what is known as a squib round. So the completed round of ammunition weighs about 300grains (1 grain = 0.0647 grammes) or about 20 grammes. If the loaded round is a "squib" it will be missing the 45grains of gunpowder so only weigh 255grains (16.5grammes) I have been looking for a sensor to use for this to no avail, any ideas please?

In the second job I want to be able to dump 1000 projectiles into a hopper and have the ardrino separate them out by weight into batches. The nominal weight would be anything from 50grains to 230grains. (3grammes to 16 grammes). It maybe I need a second, finer sensor for this job.

gzcwnk: I would like to build an Ardrino unit to accurately measure small weights, specifically bullet reloading components such as projectiles and gunpowder.

So in the first instance as a learning thing I want to detect what is known as a squib round. So the completed round of ammunition weighs about 300grains (1 grain = 0.0647 grammes) or about 20 grammes. If the loaded round is a "squib" it will be missing the 45grains of gunpowder so only weigh 255grains (16.5grammes) I have been looking for a sensor to use for this to no avail, any ideas please?

Tried google much? There's lots of information about similar projects. This 20 gram x 0.001 gram scale ought to meet the weight requirements for your first "job." (No Arduino required for the first "job," far as I can tell from your post.)

And you could hack that scale for your second "job." I did that with their 200 g scale - wasn't too hard to do. This 20 g scale would be more physically "delicate" and subject to damage from accidental rough handling or whatever.

What's your experience with building this sort of thing?

I want to be able to dump 1000 projectiles into a hopper and have the ardrino separate them out by weight into batches

That will probably take some mechanical engineering skills. How do you imagine this working?

A lot of digital balances have serial ports.

I have two balances which have RS232 serial ports. It's pretty easy to convert the RS232 signal to a microcontroller friendly signal. A MAX232 can be used to go from RS232 to a 5V logic and a MAX3232 can be used for 3.3V logic devices.

jremington: That will probably take some mechanical engineering skills. How do you imagine this working?

Probably like this. A bit larger if he's weighting lead bullets though.