HI
For my hobby project I am looking for a solid flow sensor so I can control the amount(mass) of coffee beans to dispense to the milling compartment.

 

HI
For my hobby project I am looking for a solid flow sensor so I can control the amount(mass) of coffee beans to dispense to the milling compartment.

You can arrange an assorment of bins (like segments of a paddle wheel) with each segment having a well-known volume. You can then count the number of turns, or fractions of a turn the wheel makes, as it dumps and reloads its contents. It should be an easy job to calibrate the mass of each bin's worth of beans.

 

The mass of a given volume of beans will vary quite a bit depending on moisture content. French Roast will weigh less than City or Full City Roast. If mass measure is what is truly wanted, some type of spring scale could be used. Run the feed into the scale until the pre-determined weight is measured, then dump into the burr-mill.

The beans are normally measured by volume, though, are they not? KL7AJ's idea would certainly work for an accurate volume measurement.

 

Use a conveyor belt to move the beans on a sensitive scale and then use a mechanism which will take the beans from the scale for further processing.

 

As a coffee roaster myself, it really is best not to grind the beans until just before you brew. It's still better coffee, if you grind a few days worth in advance, but it only takes a minute or so. The best cup is the morning after roasting, still noticeable better a week later. Wouldn't even care to guess how long store coffee has been sitting. Starbucks... get about the same out of a vending machine, but some people seem to like that smokey taste.

Are you looking to grind coffee for your personal consumption, or in bulk for a restaurant, or Starbucks? For bulk, would just regulate the speed of the feed into a hopper. Just run it about the same speed as the grinder. Maybe some cutoff if the hopper reaches a certain level, to avoid over flowing, just in case the mill doesn't keep up consistantly (different grind, variety of bean, time to clean).

 

Thanks Harvey for your assistance.Can you please tell me, is it possible to make hopper in home.On google it is quite expensive

http://www.home-espresso.com/category/03.025.grinderparts.hoppers/

Is there any guide which explains the working ,a flow control and interfacing with microcontroller.
I only able to found about hopper on wiki especially in paintball section

http://en.wikipedia.org/wiki/Paintball_marker#Loaders


Also just regulate the speed of the feed into hopper can you please elaborate ,do I need to store beans in compartment above the hopper or can I store directly into it.

 

I was just trying to visualize what you are trying to do. Personally, I just dump about 1/2 cup of beans in the bur grinder and push the button. Grinding a large quantity in advance isn't something I need to do. The coffee is ground, in about the same time as it takes to get the coffee pot ready to brew.

Those hoppers you linked to, are expensive because they are replacements, most likely for some stylish, high-end, name... You got to pay to brag...

You should look over the web, for further reading on coffee beans, home-roasting, and such. There is a lot of of information you should consider. Anyway, I store my beans air-tight, and in out of the light, room temperature. Don't know if this is ideal, but good enough. I'm not overly precise or picky, close enough to what I've read (been a few years since I got into roasting coffee).

Still not entirely sure what you are working on, or hope to achieve in this. I mostly roast for personal use. I'm not the most consistent roaster, since it takes about 18 minutes/pound, I get side track easy... Anyway, the freshly roasted beans, if not done StarBucks-style (burned), have almost a natural sweetness for a few days. It's not something you find in store coffee. I still like coffee, regardless of how long it's been on the shelf, it just something most people have never experienced.

Best I can offer, is search the web for home roasters, and see what other people have built, or what you can buy. Look at what you have on hand, or can acquire, and what sort of construction skills you have. I'm pretty weak in the fabrication department, not pretty, but functional... My first coffee roaster was simply a hot-air popcorn popper from the '70s, been sitting on a shelf almost forgotten, until I saw it on the web used to roast coffee, bought some green coffee, been hooked every since. The roaster I use now, also from a web design, is the top portion of a table-top convection oven, and the bottom portion of a Stir-Crazy popcorn popper (which need the heater disconnected, and a few other mods).

 

I am trying to automate the the process of grinding required amount of beans , tamping it, brewing it then adding milk to it and sugar.In other words I am trying to build a coffee machine (small scale version for personal use).

It is a big project of mine.The first stage is grinding the required amount of beans like 5ml ,10ml.

I can find lots of liquid flow sensor but could not find powder.KL7AJ suggested paddle to control flow.I am thinking of using servo motor so I can accurately control the rotation.Is it possible to use liquid flow sensor for coffee bean.

 

Okay, so you want to just push a button, and fresh cup of coffee (espresso+, spare the profanities) comes out. Sorry, I drink straight black coffee, same with espresso.

Sounds like a cool project though. Would be tough to consistently and accurately measure the beans themselves, as they vary in size and density. Even in the same bag, some varieties of green beans are of various sizes, some are pretty consistent. After roasting, much of the moisture has been driven out, some beans expand quite a bit. I've got a hunch regardless of how you measure the beans, you will either have an excess of ground coffee, or be a little short. Measuring after the grind would probably be better. A timer on the grinder would be close enough.

Don't know a lot about make espresso, I just pack it in there best I can by hand, never measured anything, just fill it up until it packed down pretty good near the top of the filter. My bur grinder also produces some fine dust, that collects and needs to be removed, which I save for the espresso machine.

I'm starting to see ways of doing the grinding and tamping, using just volume measurements (PVC tubing), but not too sure how to automatically move the filter into the machine, needs to be twist-locked into place, quite a bit of pressure there.