Ok, Here is my problem. I have a NS Oscar that I'm just getting to know, and a Mazzer Mini. Currently my preferred coffees are Intelligentsia Black Cat, and Metropolis Redline, and also 49th Parallel Epic. In an effort to improve my results, I recently got a scale which I believe is accurate, tho' I intend to calibrate it, and a click tamper to assure replicable tamping, as well as a naked portafilter to see what's happening to my extraction. When I weigh out 15 gms of coffee, it appears to massively overfill the huge basket in my NS naked portafilter. I tamp with an Espro click tamper to 30#. I extract about 1.5 oz that appears to have nice crema and a reddish brown hue over 25 seconds. BUT the coffee is WAY too thick and bitter. Am I using too much coffee? Is there something wrong with the Oscar's pressure or temperature?? Any ideas would be helpful. In the past, I just "eyeballed" a full portafilter basket and tamped by feel, and I got better, if somewhat inconsistent results. I DO redistribute the coffee before tamping.

Even if your shot looks great it seems over extracted by your description. Often the most beautiful shot are over extracted shot. Try grinding a bit coarser for a higher final volume in about the same time.

And if your using the stock basket of 58mm, I don't see any problem using a 15g dose.

How is the shot from the naked portafilter? Is it channeling, uneven extraction? What is the accuracy of the scale, 0.1 gram? It could a couple different things. Channeling (spritzes or uneven extraction), the coffee could simply be better at a different extraction ratio. I think the Oscar is a heat exchanger machine, what is your cooling flush timing like? The coffee may work better at a lower temperature.

Well, I tried to calibrate my scale, and it turned out to be TOTALLY off. Now I have a new scale, and I believe my dose and tamp are replicable. So is the coffee I'm using. My flush time is about 3 sec and I can see the spritzing stop. I'm ready at that point to dose and tamp. I definitely DON'T have my grind and tamp tuned in, as I can see some irregularity as the extraction begins. But the color and crema are more on target, and the taste is pretty darn good, if I do say so myself. I'm definitely making progress. Thanks.

Other than off-level, tamping is irrelevant as long as it's consistent. Concentrate on distribution.

cafeIKE wrote:Other than off-level, tamping is irrelevant as long as it's consistent. Concentrate on distribution.

+1 Tamping cannot create good distribution, only preserve it.