Open source screw counting machine

My recommendation is not to jumble them up in the first place.

If you have a bunch of small, used, jumbled-up fasteners, just chuck them in the bin. Small fasteners are cheap enough that it's not worth sorting them.

I have a storage bin rack on my garage wall, with one bin each for (new, used) * (nut, bolt) * (M4, M5, M6, M8, M10). (Actually, in practice, I don't have enough of anything except M6 to justify separating new and old, so only M6 is broken down that way).

But if you keep them sorted it saves a lot of time.

Some mechanism to separate individual items, a conveyor belt, maybe two cameras and then train some neuronal network on classifying the images. Training data is easily generated by feeding in a couple of boxes with known identical content. Not sure if you can get the neural network to generalize to before unseen dimensions, if not it will only work for sizes in the training set. Maybe some lights for more consistent lighting. Then you still need a bunch of containers to sort things into, maybe along the conveyor belt and pistons to push things into the correct containers or reject them because identification failed.

If you want to cover a wide variety of sizes including very similar sizes, then it could maybe become hard for a neural network to get the sizes right? So maybe just let the neural network classify the items and orientation, then measure dimensions in the image, maybe using stereo images. This will however now probably require manually labeling training images. Do you also want to read the grade and specification? Do you want to deal with coated, old, rusty or dirty items?

Interesting project, but that could take some time to get working reliable enough to be useful.

While I agree with that when I need twenty nails, if I needed twenty million nails I would certainly want to buy them by the pound, instead of counting them one by one.

For very large numbers, it is always easier to count them by measuring either the total mass or the total volume of the items, instead of counting them, and then compute the numbers by dividing to the mass or volume of an individual item.

That is why in all chemical reactions the recipes are given by measuring the ingredients in grams or milliliters, even if what really matters are the numbers of molecules that must be combined. Because counting one by one the molecules is hopeless, the numbers of molecules are typically expressed as multiples of the Avogadro number, which is the number of molecules that would be contained in one gram of a substance whose molecular mass would be 1/12 of that of carbon 12.

So not only the nails, but also all chemical substances are usually counted by the gram, by the pound or by any other mass unit.

you can buy trivial amounts (10-100) in small packages with precise count. non-trivial amounts are sold by weight because no one is counting them. the approximate count per pound is usually specified.

You could move to Europe, I've never seen screws and nails sold by anything except count, up to counts of 100-1000. Perhaps if I were to buy much more than that it would be by weight here.

Speed.

If I need a handful of 5/16" screws, then odds are that I will also need nuts, washers and possibly lock washers. Instead of having to count out 10 each of all of that, I just grab a handful of all of them, toss them into a bag and the cashier weighs them and tells me the cost.

yeah i came here to say, this is a job for a scale.

The linked youtube video may answer some of your questions.

The issue is that you need to built it twice, so that you can disassemble one to get the count of screws :P