Continuing from the previous post on flow-rate hack and gravimetric espresso project, I have been able to control the pre-extraction flow-rate, extraction flow-rate and extraction pressure of the espresso using a low-cost hack.
Disclaimer: I am not liable for any damage, death or injury caused through the use of this hack.
The AC voltage controller which is hooked up to the Ulka vibration pump.
In this video, the AC voltage controller (pump controller) was gradually tuned to allow soft and slow infusion. During the extraction phase, the controller was tuned further to alter the extraction pressure.
The following parameters were used:
- 20-g dosage in portafilter
- 50-ml target yield
- IMS 20-g basket
- machine set to 9-bar max
Gravimetric dosing was enabled to cut-off the pump automatically when the target yield is reached so I can focus on toying with the pressure.
And the result? The coffee was obviously tastier than another coffee made with the same parameters except with a flat extraction profile.