Mazzer Major - arduino mod

[woodenteapot]

Hi everyone,

I started a home project this week to modify a Mazzer Major doser variant to become electronically controlled.

Since I single dose my grinders at home, I want to eventually press a button and have close to zero grind retention.

So my plan is for the arduino to:

1. Start grinder for a set time
2. Stop the grinder, activate a blower (I'm going to trial using a fan for now)
3. Start grinder for a short burst while blower continues to push grinds out

I see a flaw in my plan in that using a fan would aerate the ground coffee and make them go stale faster... I would like to use the fan in short bursts but I'll have to see how it goes... If I can find some sort of air pump with an accumulator to burst air, that'll be ideal, but I haven't come across one that isn't custom made.

My progress so far:

• Figured out how the electronics internally work
• Programmed my Arduino board to enable the user to change the grinder run time and run the grinder
• Tested the setup to switch the grinder on via the Arduino controller

Problems faced:

• The Mazzer Major motor controller is weirdly setup, one switch switches the motor on, but another switch is required to stop the motor (this is done via the "twist start" or doser lever switches and the doser "full" switch near the grinder chute)
• I only had one relay switch for the Arduino board, so I'm waiting for another relay to arrive

I've attached a video and some photos of the progress so far (you can see from the images, it's DIRTY, I got it secondhand from a cafe that changed owners). Not very much documented here cause I only thought of documenting it for you all later after starting the project.

I'm open for ideas if any of you have some! I'm happy to share my Arduino code when everything is done too!

[Andy]

Great home baked project, thanks for sharing.

As for the blower, my first thought is something like a fish tank bubbler with a homemade reed valve that could be as simple as the neck off a balloon to provide some back pressure before release but something like a pushbike tube valve might work too.

Will be interesting to see what you end up with.

[Dimal]

Very interesting indeed....

For an Accumulator, a small R/C aircraft fuel tank is pretty strong and can be pressurised. As for a quick release, maybe a servo operated clamp on the "balloon neck'/10mm thin walled silicone rubber tubing, as Andy suggested...

Mal.

[fg1972]

From RC planes you can also get fairly small air tanks used for air operated landing gear and or brakes. These tanks are usually pressurized with a bicycle pump or even those hand held battery operated pumps.
There are all sorts of valves that are usually operated via a servo to release the air.

[Dimal]

Yep...

That's right about the gear pneumatics. The only ones I've ever seen were quite small in volume though, and I'm not sure if even the largest valves were of sufficient cross-sectional area and quick operation, to exhaust the tank instantaneously, as it were. Mind you, when I was last active in R/C aircraft was about 20+ years ago. I sometimes forget that time moves a lot quicker these days...

Mal.

[woodenteapot]

Wow, thanks for the input guys! I'll look into what I can get my hands on (without blowing too much money at it - the wife may not take it too nicely)

Really interested in the idea of using a balloon or bicycle inner tube (I've got lots of punctured ones) to hold the pressure.

RC airplanes is something I haven't thought of looking into for pneumatic pumps, might be worth looking into.

Cheers,

Mark