I feel like I should be writing a blog - "Area Man stunned by revelations already well understood by others". Kind of an autobigraphy....

Anyway, with the help of the kind folks here I have grasped the basics, am able to pull good shots, and now really don't like that which squirts out of 6 week old jura $uperautomatic. Thanks all! This all with a handful of dark or med-dark espresso blends.

https://www.trebilcockcoffee.ca/coffee
http://anthonysespresso.com/Coffee/Anth ... occo%20Bar


I have been buying locally roasted, very fresh coffee beans and enjoying the eye-opening ride and the variety, and was gifted a small container of a lighter medium-roast Colombian, and thought I'd give it a shot. (or several) http://www.chaloscoffee.com/#!product/p ... dium-roast

Suddenly (!) the grind was WAY out and the cup overflowedeth in seconds. I ground finer, same thing, ground really fine, choked the shot, ran out of coffee before I could dial it in. Switched to a darker roast, tweaked it, and am now enjoying a really delicious after dinner espresso.

(I should mention that I have a commercial grinder so it is tricky to be economical with the coffee. Kind of like buying a dumptruck when you need a wheelbarrow. This will be another chapter in the autobiography, with several examples.)

Anyway, all this to ask - what gives? How does the degree of roast impact the absorption or resistance or whatever it is that creates the magical 9 bar vs 30ish sec puck-balancing act?

Thanks all, great fun.

Dave

Fines production maybe, due to how bean shatters or pulverizes during grinding depending on how compromised (roasted) its structure is. Darker roast might seem to have more volume when ground too.

Changing roast level requires a rethink of grind, temperature, and dose. A lighter roast might work better hotter, and finer or just using bigger dose.

How old are the grinder burrs? Worn burrs can give those results.

Unless you have a really good grinder (what some on HB refer to as Titan class, which is a step up from an ordinary commercial grinder) it can be very hard to pull a good shot with lighter roasted coffee. Lighter roasts need a finer grind to get a decent extraction and a grinder that is not up to the task lacks the precision to dial it in properly - resulting in either too fast a flow or choking it with too much fines. Better grinders allow going finer without overproducing fines. Darker roasts are much more forgiving with a subpar grinder as you can get away with a coarser grind. At least that's been my experience.

The grinder is a San Marco SM90, so a physical titan, but probably not "Titan class" to the cognoscenti. It is a stepped commercial grinder, quite precisely machined, and very fine thread pitch vs others I've examined, (also, ZERO play evident between steps, in practical terms - so, if not titan class, it may not be too bad either) Unfortunately, I could have been more methodical before I blew through the coffee, and jumped several steps to "way too fine" before running out, so I cannot say whether the ideal was between steps or not.

All irrelevant if the burrs are dull...
The burrs are chronologically old, feel sharp, but I don't really know how to assess. I expect they are the 1985 originals. The grinder and the machine were purchased from the adult children of a very elderly italian couple who were selling their elderly parents' home. The folks had imported the machinery and a fantastic custom-made espresso bar from italy for their rec room. (mid 1980s) The commercial fridge in the bar and the sink had never been connected... So, very little use, and the whole shebang basically sat unused for decades. See what I mean here:
Startup of long dormant La San Marco 85-12-1 - process? ?

Great info, food for thought, and helps explain my experience. Obviously will need to try again to confirm.

Thanks!

Dave

Sounds like it's worth starting with being more methodical in dialing it in. If you continue to have issues, then I'd go with Gary's recommendation and try some new burrs before changing your grinder. Good luck!

If you can get to the burrs, see if they will shave your fingernail. If not they're worn out. Also stepless is easier to dial in generally than stepped unless you're dealing with an HG-1 where the settings, I'm told, are very close. Ken, since you have one maybe you can speak to that point.

I can, and did when I first got it and cleaned it, and I know they won't do that. OK, good to know. Will start there I think. Great help gentlemen!

Dave

Darker roasts and lower grown softer beans tend to produce more fines when ground. Take a dark roast bean and a light roast bean and break them in half with your fingers. The dark roast bean will break and crush much easier. They do the same in the grinder. A light roast or exceptional hard bean like many African origins or peaberry varieties will take a finer grind due to the way the bean fractures in the grinder. That is one of many possibilities, older beans will also gush at the same grind setting. Just tighten up your grind, unless the beans are old. In that case, open up the grind and dose higher, or put them in the flower bed for fertilizer.