DIY bean doser - Page 2

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#11: Post by bostonbuzz »

Kudos, I wish I knew the first thing about coding!

I say spring auger because that's what is really doing the work in horizontal axis grinders with an auger. The metal auger is sort of ceremonial but the big spring is really doing the work and not crushing too many beans being all springy and whatnot.

10-20 iterations, wow. :shock:
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Kran (original poster)

#12: Post by Kran (original poster) »

I know just enough about coding to be able to google and then apply to my application.

Now I understand what you mean by spring auger, like on an EK43. I was thinking more like on and Ode or Xeoleo, where it's one piece of metal. New wrinkle to think about, thanks.

10-20 iterations of the auger isn't bad at ~1hr per print. 5 iterations of the main body at ~12-16 hrs gets a little intense. I should really upgrade my 3D printer, but then I wouldnt have fund for my next grinder etc. Too many hobbies.


#13: Post by Pressino »

another_jim wrote:Um, you are thinking about the variance in weight of a fixed number of beans; this problem is how close you can get to a fixed weight with a variable number of beans. if it's 5 beans precisely per gram, you'll get 14.8, 15.0, and 15.2 every time. If the beans vary from 5 to 9 per gram, you can randomly chose beans, and stop when you reach either 15 or 15.1. Since no bean weighs more than 0.2 grams; you cannot skip from 14.9 to 15.2 with one bean.

If you can pick and chose, you can get even more precise. For instance, when you buy a three pound package of onions at the grocery, each onion is about 1/3 pound, but the package is usually within an ounce or two, since the sorting machines do some weight sensitive picking and choosing
Right, that was exactly my point. If, say, all your beans weighed 0.2 grams you could get 15.0g (or any other whole number of grams) exactly all the time. But some of them are going to be a bit heavier and some a bit lighter (not to bring in the matter of fragments). So you do need to "pick and choose" to some degree to get more accuracy. The smaller the particle size/weight, the better the augur system works for measuring those particles. Of course, your desired accuracy is also an important consideration. RCBS, for example, has powder measure scales that work quite well for reloading purposes, within a given range of powder characteristics.

As regards very accurate measurement of coffee for dosing purposes, higher weight accuracy and resolution can be achieved by measuring ground coffee, rather than whole beans, which I believe is how most (all?) dose-weighing grinders work.