Ive been thinking the pump pressure on my San Marino CK was too high. To get a 60ml shot (from the double) in 25 seconds, I have had to adjust the grind down finer than I use on the Silvia. Then the shot seems burnt and over extracted.
So I unscrewed the spout on the PF and attached a pressure gauge. The pressure built up smoothly to 6.5 bar over about 6-8 seconds, then held steady. Much lower than I had expected.
Is this too low? And if so, and I increase it, wont I then have to grind even finer?
I then put the gauge on the Silvia as a comparison, and she pumped upto 10.5 bar over about 5 seconds.
So can someone explain to me why it is that if the grind and tamp are the same, I get a faster extraction from the CK with 6.5 bar, compared to the Silvia at 10.5 bar. The only other differences between the 2 (as far as I can see) is that the Silvia does take about 2-3mm more in the basket. Is this enough to make the difference?
The other variable is the jet size. I pulled out the jet on the CK and it is tiny. I measured it at about 0.8mm. I have read somewhere that this is about right.
Any help and advice gratefully accepted.
Cafeoholic.
So I unscrewed the spout on the PF and attached a pressure gauge. The pressure built up smoothly to 6.5 bar over about 6-8 seconds, then held steady. Much lower than I had expected.
Is this too low? And if so, and I increase it, wont I then have to grind even finer?
I then put the gauge on the Silvia as a comparison, and she pumped upto 10.5 bar over about 5 seconds.
So can someone explain to me why it is that if the grind and tamp are the same, I get a faster extraction from the CK with 6.5 bar, compared to the Silvia at 10.5 bar. The only other differences between the 2 (as far as I can see) is that the Silvia does take about 2-3mm more in the basket. Is this enough to make the difference?
The other variable is the jet size. I pulled out the jet on the CK and it is tiny. I measured it at about 0.8mm. I have read somewhere that this is about right.
Any help and advice gratefully accepted.
Cafeoholic.

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