Can someone explain the Normcore tamper to me? - Page 4
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Deephaven
That is my understanding of the normcore as well. When you bottom out there is the spring applying force between the shaft you are pushing on and the coffee. The spring then limits the overall force to "25lbs". I put the weight in quotes as springs all follow Hooke's law so if have a higher dose than expected it will be more force and a lower then less force but should be consistent for the same height of coffee in the portafilter .
That being said I have done no testing on mine, haven't taken it apart and looked at it to verify, but any other design makes zero sense....
That being said I have done no testing on mine, haven't taken it apart and looked at it to verify, but any other design makes zero sense....
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LittleCoffee (original poster)
I've been ruminating on this some more and I think people are right - you are supposed to bottom out the Normcore, which gets you consistency by passing any force greater than that needed to bottom out through the portafilter via the sliding collar. You still have the problem that depending on the length of compressed spring you need to reach the "bottom out" point (which depends on how much coffee you have in the PF) the bottoming out pressure will vary, but hey it's a cheapish tamper.
Now the Barista Hustle article quoted earlier has this chart in it:
Is this an accepted view of the world? It seems theoretically very simple - perhaps a bit too simple for my liking. But in any event, I was curious as to whether at "bottoming out" pressure I'm getting to the horizontal part of the chart or not. So I did this:
1. Using bathroom scales and the weakest Normcore spring (I still can't bring myself to call it the 15lb spring) I saw that just before I bottom out I get to around 25lb of pressure. With my 14g of Sumatran Mandheling I got 28g of coffee in 28s with an extraction which looked good on my naked portafilter (and after having sacrificed some beans to the grinder retention gods). I made a cappuccino so you'll forgive the lack of precise tasting notes, but past experience tells me this is a well extracted shot.
2. I then repeated with the middle spring (25lb sic) keeping everything the same (to the best of my ability!). It was just before bottoming out somewhere around 47lb of pressure. The shot extracted in 30s, which is a level of variation I would not describe as statistically significant for my set-up/skill level. However, the following shot extracted in 37s with the medium spring. I still don't know whether that's because of the heavier spring/tamp pressure or because of my inconsistent technique.
So on the face of it, that chart is probably how things work. But it's still unclear whether the 25lb spring gets to the horizontal section or not.
Happy tamping!
Now the Barista Hustle article quoted earlier has this chart in it:
Is this an accepted view of the world? It seems theoretically very simple - perhaps a bit too simple for my liking. But in any event, I was curious as to whether at "bottoming out" pressure I'm getting to the horizontal part of the chart or not. So I did this:
1. Using bathroom scales and the weakest Normcore spring (I still can't bring myself to call it the 15lb spring) I saw that just before I bottom out I get to around 25lb of pressure. With my 14g of Sumatran Mandheling I got 28g of coffee in 28s with an extraction which looked good on my naked portafilter (and after having sacrificed some beans to the grinder retention gods). I made a cappuccino so you'll forgive the lack of precise tasting notes, but past experience tells me this is a well extracted shot.
2. I then repeated with the middle spring (25lb sic) keeping everything the same (to the best of my ability!). It was just before bottoming out somewhere around 47lb of pressure. The shot extracted in 30s, which is a level of variation I would not describe as statistically significant for my set-up/skill level. However, the following shot extracted in 37s with the medium spring. I still don't know whether that's because of the heavier spring/tamp pressure or because of my inconsistent technique.
So on the face of it, that chart is probably how things work. But it's still unclear whether the 25lb spring gets to the horizontal section or not.
Happy tamping!
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Blernsball
Yes. Or at least it should be.Is this an accepted view of the world?
Once the puck has been fully compressed, tamping any harder doesn't do anything. Voids between grounds have been eliminated. There is nothing left to do. It doesn't take much force to compress it fully.
If you are not compressing the puck fully you are needlessly adding another variable that is hard to control.
I suspect the origin of the guideline to use a certain amount of force when tamping was to make sure baristas in training compressed the puck fully every time. Unfortunately this lead to home baristas turning it into another specific variable that now needed to be obsessed over. Which then leads to all kinds of gadgets.
If you want to know how much force you need to compress the puck fully, measure the depth of the puck in the basket as you increase the force. You'll see it eventually reaches a maximum. For the normcore, try with the lighter spring, then the medium. If the medium doesn't compress the puck any more then the lighter one then you are have reached maximum compression and don't need to worry about it.
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