It was just about time. Too long have i been waiting for some parts. I received my powerful 12V steppers and my favorite IRF540 mosfets. After several hours of brainstorming and many many failures, i came up with the final dispenser mechanism. I tried some more complicated ways, yet once more it proved that, "mechanics loves simplicity because it works".

So, first of all, i had to make a controller for my stepper motors. The motors i got are unipolar hybrids with 7.5^o step. I only want to rotate to one direction, so i made a very simple full-step controller. I did not want to have half-step, as this accuracy (7.5/2) would be way too much for my application. So, here is my simple unipolar hybrid full step stepper motor controller (as usual, i consider such circuits or theories as stand-alone entities and therefore i present them i different pages).

Then, i made a quick model to see if my idea works. It should work, as i have seen it working several times, yet i do not know if the motor, the speed and the worm pitch would fit my needs. oh i forgot to mention the design. I will use a worm from an old printer that i chopped once. This worm was pushing the ink. After 3 days of soaking inside some cleaning fluids, it was as clean as new. For my temporary model, i used a 0.5 lt water bottle and a 14mm plastic tube.:

I cut the top of the water bottle	I cut the tube to about 15cm length, and with the angle grinder i removed a piece from the middle	With the cone drills i made 2 holes one opposite the other for the tube to fit	This is the first test module

Then i had to somehow fix the worm to the motor shaft. Easy:

For such jobs, i use the cable connectors! Perfect and cheap coupling for low speed applications.	This is the motor assy

Using the stepper controller, i run a first test. The results were more than great! Full success. The motor torque is more than needed for this application, and the speed is high enough to empty the whole 0.5lt bottle in less than a minute. So, i began making the final module:

My new materials: A pair of 800ml PET containers with rotate-to-lock caps, the worms and an aluminum tube (not plastic).	I cut the aluminum tube to size, and drilled with the cone drill the container. The tube fits perfectly and firmly!	With the dremel i removed the piece from the tube	This is the assy with the worm inside. Looks great!

It took me so many days of thinking and theoretical problem solving of this module! And yet it took me less than 2 hours to make it work. I really cannot tell you how difficult it was to come to this final design. It looks ridiculously easy but it is not. So, i made a temporary base to test it once more, and here it is:

Absolutely ready to be mounted to the coffee machine! And of course, i made another one exactly the same as this one for the coffee... The project is coming to an end!

The base that i had above was only for test. Here is the final version of this module:

The new base is made of waterproof wood 16mm and 8mm acrylic glass	I cut a piece from the acrylic glass and marked-drilled the motor holes on paper tape	The motor is fixed on the acrylic glass plate and the plate itself on the wooden base	This is more rigid than before isn't it?

Now a base for the tank:

From the same acrylic glass i cut a longer piece	Marked and drilled 4 holes on the corners	I used the same piece as template to drill the same pieces on the wooden base	I made these holes through, and from the bottom side drilled them larger diameter to sink the nuts
4 M3 pieces from a ling screw will hold the tank platform	I used 2 screws for each one to fix it on the wood, one above and one bellow, sinked in the hole.	Then i put an extra nut on each one. The platform will be placed on these nuts...	...like this. Now i can level the platform parallel to the wooden base (and parallel to the motor shaft!)

And finally...

Using a precision measuring tool i leveled the platform with the base in all 4 corners	And then i placed the tank on the platform	I used hot-melt glue to fix it on the platform. The platform has larger in diameter holes, so that it can be moved (and adjusted) to it's plane...	...and it can also be adjusted to the plane of the base... After some adjustments, the shaft rotates absolutely free!

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