Category: Coffee

  • 3D-Printer and Your Coffee Grinder

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    Two weeks ago I acquired a 3D printer; specifically the Printrbot Simple Metal Kit and, after some warranty help, it’s printing well. The first thing I printed was the fan shroud for the 3D printer itself, as recommended by Printrbot, but the next things were for my own design. I printed a set of three…

  • Coffee to Water Ratio

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    A friend of mine (thanks Marc!) forwarded the linked article to me last week.  While it is more of a coffee tease sort of thing than anything else, it just so happens that the article discusses the coffee/water ratio used by some of these gluttons.  You’ll be surprised how modest my recipe looks. New York…

  • Coffee: Model Fitting Goodness

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    You have seen the response function contours through the stationary point, and you have seen the 3D response function visualizations. You may recall that I have two competing models, one is derived from the experimental data design for the response surface, and the other is all that data and the screening results too. Is either…

  • Coffee: Visualizing the Response Function

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    I have been calling my 3D response function a “surface”—which is linguistically feckless at best. Of course, I have some company, the immortal Box, Hunter, and Hunter call the experiment design a response surface method. So note carefully, the response function is not a surface, it completely fills a volume. Naturally, this is hard to…

  • Coffee: Analysis & Results of the Response Surface

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    I have executed the experiment design discussed Coffee: Design of the Experiments (Part 2: RSO). This “response surface method” experiment design is carefully crafted to provide the data necessary to fit a formula of the form q = b0T2 + b1t2 + b2r2 + b3Tt + b4tr + b5Tr + b6T + b7t + b8r…

  • Coffee: Considering Cold Extraction

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    I won’t start the cold extraction experiments until I finish the response surface set, and possibly until I perform some local optimization using the RSO outcome. To warm up, paradoxically, here are some thoughts on cold extraction. The basic process, everywhere I’ve read about it, is to put grounds in room temperature water for a…

  • Coffee: Design of the Experiments (Part 2: RSO)

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    In Review The results of my 4-trial fractional factorial experiment (main effects) showed that extraction time is the most important variable, and that temperature and C/W ratio are less important. In the interest of completeness this experiment will not simply vary extraction time, but rather seek to efficiently find the maximum. Lessons from the Screening…

  • Coffee: The Detestitron

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    Please, when you are shopping for a grinder, don’t believe anything you hear (except what I tell you…). A blade grinder is probably as good a grinder as you want to afford. Don’t presume that a burr grinder will automatically produce a more consistent grind. Take, for example, my manual burr machine. Compare the grind…

  • Coffee: Analysis & Results of the Main Effects Study

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    I have conducted the trials in the following table. Actual Values Statistics Jargon Trial r (g/ml) t (sec) T (F) r t T Q 1 0.035 10 205 -1 -1 +1 2.5 2 0.075 10 185 +1 -1 -1 3 3 0.035 300 185 -1 +1 -1 4 4 0.075 300 205 +1 +1 +1…

  • Coffee Design of Experiments (Part 1: Screening)

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    I will invoke a variety of principals from experiment design methods. The truth is, though, that I’m self-taught in experiment design. It is altogether probable that there are better ways of conducting this experiment which my ignorance has hidden from me. I’m open to suggestions! Quick Review The variables in control are temperature t, extraction…