Grind too fine?

[artisansweets]

I just got a slightly used Rancilio Silvia machine. I can't figure out all the components to get the perfect shot. It seems as if the grind is to fine and when tamped there is very little water that gets through. The shot dribbles out and is not complete within the 20-30 desired time. I've tried a slightly courser grind and it was a bit better but almost to watery. I have had a few successful shots but haven't figured out the common denominator.
Any suggestions?

 

[cafemakers]

Assuming that you (correctly) shoot for a target extraction time within the approximate range of 20-30 seconds, there are 4 remaining variables that you can control in this equation:

1) grind
2) volume of coffee
3) tamp pressure
4) volume of water

We will assume for now that the machine is calibrated to properly control the 5th and 6th variables, the temperature and pressure.

As a guideline, I suggest that you first measure the volume of coffee that you are placing in your portafilter - best to use a gram scale if you have one available. The volume of coffee in your charge should be in a range of 7-9g per shot (2x for a double basket) - it is also acceptable to use more or less coffee, but you will need to adjust your grind to be more coarse or fine, respectively for the equation to work.

Next, practice tamping on a simple bathroom scale. The pressure exerted should be within approximately (again, we deal in approximates here) 30-50 lbs. Like the note above, you can use more or less, but will need to grind more coarse or fine to adjust.

Now that these two variables are close to being fixed and you can eyeball the extraction volume in a measured shot glass, you can run test shots with your machine until you tune in the combination that works best for you. Note that a good burr grinder with fresh burrs will go a long way to improve the consistency of your output - also pay close attention to the coffee freshness and water quality used; I suspect that from the specific nature of your message that you have already researched this.

There are a few other points of procedures mentioned in the example we provide online from our commercial training curriculum, here: http://www.cafemakers.com/espresso-steps.pdf

If you are working within the parameters suggested above and still find that you are not obtaining ideal results, I suggest that you may want to have the machine reviewed by a technician for possible service problems. Temperature and pressure instability will cause poor and sometimes unpredictable results.

Be sure to write back and let us know how it turns out.

Best of success!

Andrew

 

[artisansweets]

Thanks for your insightful response. I will let you know how it goes.