What is puckology?
Puckology is simply analysing the spent coffee puck after a shot has been made. Whilst it is by no means scientific, it can provide useful feedback regarding the preparation of the coffee before brewing and extraction during brewing.
With the Robot, however, spent puck analysis is not possible because the results are very misleading. After pulling the shot and then raise the arms again to remove the water, this draws air from below the basket, up through the coffee. It will therefore dislodge the puck or even form a crack in the cake. So it is largely meaningless on the Robot.
For example if we refer to the photo below of a used coffee puck from a very good espresso shot. You will notice a large crack in the cake, we would therefore assume channeling had occurred and our preparation was not ideal. However because we have raised the levers, air has been introduced and cracked the puck.
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What if I have an uneven espresso puck
1. Tamping is key. Make sure the espresso puck is level and flat before and after tamping.
2. Try the 'tap' technique. Test the result by using or not using the WDT. Then level the basket via horizontal and vertical taps before tamping.
3. Observe how the coffee emerges by using the naked portafilter. Water follows the path of least resistance and then starts channelling.
What if the espresso puck has "donut" extraction
1. Try preheating the basket and portafilter. Pour some hot water in will work.
2. Grind finer (always the key if you cannot get pressure)
3. Increase the espresso grams. (to 17g or no more than 20g)
4. Use fresher beans.
Most important - Keep it relaxed and simple when preparing the coffee grounds. The water may be channelling, which the uneven puck is a common problem and can be solved by stirring the grinds.