The oversized filter basket doubles as a brewing chamber. To keep things simple, there is no heating element, so you will have to fill the basket up with hot water from a kettle. As soon as you pour in water just off the boil into the basket, it immediately cools to around 95°C, absolutely perfect for brewing killer espresso.
Do not be fooled by the toy-like cutesy Robot looks, the Robot means business and is capable of pulling espresso shots like a professional machine costing 50x more. By pushing down the lever arms, the internal piston forces the hot water through the coffee creating the thick syrupy espresso. The machine is more than capable of producing that magic 9 bar pressure, but lever machines prefer somewhere in the region of 6-7 bar.
It might take some time to practice, but the Robot gives you the tools to produce great espresso shots. The biggest factor in the success of your espresso is on the coffee and grinder side. If the grind setting is not correct no espresso machine can make it work.
1. Using fresh coffee ground just before brewing is always preferable.
2. Fill the basket with hot water just off the boil up to 5-8mm below the rim. Do not weigh the water into the basket and potentially under-fill the basket.
3. Experiment with pre-heating the portafilter and/or basket for lighter roasts.
4. Tamp firmly and evenly, but don't go overboard with the tamping force.
5. Pre-infusion is letting the water soak into the coffee at low pressure before the main extraction begins. It is very beneficial for even extractions but the key is to main the pressure on the coffee during this time.
6. Do not pump the lever arms up and down to make coffee. It disturbs the coffee puck and ruins the shot.
7. Start out with a 16g dose and a 32g espresso (1:2 ratio) and adjust as needed.
8. The coffee dose in the basket range is approx.12g-20g but will depend on the bean and tools (filter screen or filter paper) used. A traditional espresso shot was always 1 fl. oz (29.5ml). Nowadays people use scales to measure the pressure weight. The quantity of ground coffee is the dose and the yield is the weight of the espresso liquid. So a 16g dose that yields 32g of espresso has a 1:2 ratio. You can experiment as you wish according to your taste.
Simple Basics of Espresso Extraction
Espresso is made by forcing hot water under pressure, through coffee. The Robot, and any espresso machine, is merely a tool that gives you the ability to do this. The main variables in using the Robot are the coffee, the water and barista. Understanding the relationship between coffee grind size and water flow is the absolute key to make good espresso.
In the simplified image below, the filter basket on the left has coarse ground coffee, on the right it has the fine ground coffee.
We can then use this knowledge of how grind size affects the coffee flow by applying it to our espresso and measuring how long the espresso takes to extract. The time it takes for this extraction will directly affect the coffee extracted by the water from the coffee grounds. A fast flow will mean less extraction than a slow flow.
How do we know which grind setting is correct?
The best way is to aim to extract the espresso in 25-35 seconds and how we achieve that goal is mainly by adjusting the grind setting. In the above examples assume only the grind setting was changed, all other variables (dose, pressure etc) were constant.
99% of all extraction issues can be solved by following those rules.
Pre-infusion and extraction
The beauty of using a manual lever is that you are in complete control of the extraction, you can vary the pressure and flow as you see fit. One of the most important stages of the extraction process is the pre-infusion stage; this is when you first add the water, the coffee is absorbing the water at a lower pressure before the higher extraction pressure. This causes the coffee to swell and is believed to set the foundations for a more consistent and even extraction. It is very beneficial to the quality of the shot.
After locking in the prepared naked (bottomless) portafilter and basket with the hot water, let the lever arms fall gently down under their own weight – keep your fingers under the arms so that you are in control as well. If the lever arms stay in the upright position, press them gently to start off with a 5 seconds pre-infusion and experiment from there.
Next push the lever arms down slowly and gently, do not release the pressure. Slowly hold this until you start to see coffee beads appear at the bottom of the basket. Pre-infusion is usually done at a much lower pressure then during full extraction. Depending upon your grind setting, aim to pre-infuse until seeing beads of coffee for around 5-10 seconds. Then press the lever arms down.
Lock in portafilter and let the lever arms fall or press them gently to start
Press gently and pre-infuse until coffee appears
Hold this position
Extract by pushing lever arms down
> 15 seconds
Shot times, the espresso stream and colour are great at giving you feedback if you have your grind setting in the right place. But the most useful tool you have is taste. If the espresso tastes good then you are doing well.
Adjust only the grind when starting out. Keep the dose and ratio consistent and adjust the grind as required. If you try and adjust both dose, output and grind at the same time you will be chasing your tail. As you get more experienced you can then adjust the dose and output ratio.