Hi there,
I'm in the planning mode to make myself an awesome drink dispencer which will be placed in my home bar, but to get started, i need some kind of pumps or dispencers, and tubing.
Can anyone point me in the right direction? I'm gonna pump both sodas, syrups and base alcohols, i also want them to be very acurate, down to 1ml, maybe 2-3ml acuracy is enough, but it needs to be pretty acurate.
Any ideas? where to buy? What to buy?
Cheers,
Jan
jastrup:
Any ideas?
To get accuracy like that, you're going to need what is called a "peristaltic pump" - the problem is, most of them run slow and steady, and are generally meant for medical device (blood and other liquid measurement, mainly). Thus, they tend to be very expensive, especially if you want larger volumes or higher speed.
The cheapest version of such a pump I have seen, is currently being sold by AdaFruit. Note that for food-grade use, you will need to change out the tubing:
Note that it only outputs 100 ml/minute, which is a very, very low rate. What you might do is a two-stage system; use a higher-speed pump (windshield washer pump would be perfect - RockAuto.com will have them cheapest) to fill at a quicker rate, then shut that off and run the peristaltic for the final amount (you would need to modify the pump to include some kind of rotation sensor - magnetic hall-effect switch or optical - monitoring the rotations would allow you to meter the amount of liquid). Of course, you still wouldn't know how much has been pumped; for accurate measurement, you need some kind of flow meter to measure the output - especially if doing the two-stage version. AdaFruit also sells one:
The problem with it is that in order for it to work, it needs a higher rate than what the peristaltic pump they sell can provide; so maybe you put it only after the high-speed pump, and then plumb from that to a Y-connector to a single output. Plumb the other side of the Y-connector to the peristaltic, then plumb a line from each pump into the bottle or whatnot holding your liquid (so two lines per liquid).
Then run the high-speed pump while monitoring the pulses from the flow meter; when you get "close", shut off that pump, then start running the peristaltic pump, and monitoring it's output pulses to fill the final amount.
Thank you alot for your answer, that helped me alot on my way, but - I've been doing some more research along my way now, and found out that maybe using two tubes into a bottle will do the trick. One tube that pressurizes the bottle up too .. lets say 5-10psi, and one tube for liquid flow connected to a solenoid valve, I might be wrong here, but this might be the best option so far.
I also thought about using windhield washer pumps at first, but i realized pretty fast that it would not be acurate enough.
I'm gonna keep digging around too se what answers i can come up with, but one thing is for sure, I'm gonna complete this project one way or another, and I'll be sure to update folks along my way.
Again, thanks for your answer, and if you have any other tips for me, just shout it out.
Check for posts by Jim_Socks; he was building a similar device - don't recall if he ever mentioned the specific dispensing hardware he was using though.
Can you put the drink glass on a scale and add ingredients by weight?
Thanks for the Jim_Socks tip! 
And yes, I guess i could use a scale of some sort to measure the contents, but then again, more things that could break, and i doubt it will be as acurate as i want it to be.