The Gaggia will be hacked to have extra functions, like a paddle, pressure sensors, preinfusion, display, ... wifi?!
Here are already some examples of hacked Gaggia Classics:
- Project Coffee: Es(pi)resso Machine
- Espressuino – DIY PID, Bluetooth and Preheat Coil on Gaggia Classic
(There are plenty more but I can not find them right now...)
I take no responsiblity nor liability that any of this information is correct.
Bill of Material
- 6.3mm PCB tabs
- Solid State Relais 1A
- Solid State Relais 10A
- Atmega like microcontroller
- 5V 4.5W Power Supply
- 230V Optocoupler
The first iteration will contain a "fake" paddle, where some range will be off-state, then a preinfusion range and then the full pump power.
A prototype made from plywood works great, and even looks good!
The paddle position is measured with a potentiometer and is also the axis of the paddle. If you take a look for example at the La Marzocco Strada paddles, you will see, that they use a wiper ring to measure the position. This seems to be a much better choise, because the potentiometer will probably break because of the high moment caused by the long lever arm.
Also this prototype was never got intro production, because I own a Auber PID now... I had some design with a proper bearing and also some spring loaded ball indentation marks but that even got never into prototyping.
For all that are interessted, here are the openscad files: GitHub: gaggia_paddle.
One easy to implement preinfusion is to let the pump run for some seconds, then switch it off, but do not open the solenoid valve. We can do this by using two solid state relais, one for the pump and one for the valve. 1A should be sufficant here - the pump needs about 50W and the valve about 15VA.
The Auber PID takes another route and just fires the brewing for a few seconds, then stops and the runs the brewing just normal. I had a talk to their technicans about adding a second SSR to control the magnetic valve seperately. They said that they had the same idea first but came to conclusion that it is not neccessary to have all this trouble. They told me, that the results are nearly the same.
Everything should be integrated in a way that it can be easily switched back to the default configuration. For this we will use 6.3mm pcb tabs and reproduce the back of the switch configuration.
This Image from partsguru can come handy here:
But beware: as I read, not every Gaggia Classic has the same color coding nor the same circuit. Some of them are different! Check other possible circuits before doing something wrong!
You will need 3 switches for that. The important thing is, that on the third switch, the lamp is always connected!
The first one is a SPST with an included lamp. The steam switch is a DPDT and the brewing switch is a SPST with a seperate controlable lamp.
I once tried to rebuild the complete switch assembly because the frame broke and a replacement part costs about 50€. Therefore I looked into the "arcolectric 1500, 1550 and 5500 Series" (see Datasheet at Farnell).
If I remember correctly you would need a 1560 switch for the steam, 5503 for power and a 5508 for the brewing. The terminal style would be "C". The body, rocker and printing style you'd to choose for yourself. So I would have choosen those 3 switches:
- C1560AAxx (Steam)
- C5503PAxx (Power)
- C5508PAxx (Brew)
But unfortunately, not all those combinations are easily orderable.
For prototyping I created a replica of the top plate from plywood. Therefore I needed to measure it beforehand.
So here is a drawing of the dimensions. This drawing was created with Autodesk Fusion and also is available as PDF.
For explaination: there are (at least on my machine) four mounting points for screws, where only two are used in the orignal version. The rectangular cutout is for a PID controller. The circular cutout in the bottom right is the position of the water inlet.