Oh, I had forgotten about Al's Rule. Jeremy goes into more detail in "How Al's Rule Saved My Life." The conclusion is excerpted below:

jrtatl wrote:The beauty of Al's Rule is evidenced only after I have my grind dialed in to the 60 in 30 ideal. When I wake up the next morning, my grind will be off slightly, due to many factors. I can still get a great shot just by watching the pour as it leaves the portafilter. If it starts by dribbling a bit, and then proceeds to a slow stream, I know my resulting volume will be low, so I need to increase the time of the pour. If the shot starts out with a steady stream, I know my resulting volume will be larger, so my shot time has to decrease.

A good feel for Al's Rule also helps when I try to judge a shot based on volume in the cup. If my cup is filling fast and it looks like my shot volume will be high, I cut the shot early to preserve Al's Rule. Conversely, when the cup is filling at a snail's pace, I let the shot run long.

After I got a feel for Al's Rule, I was able to relax, and stop timing every shot. I generally time enough shots to get the grind dialed in. Then, I can pull shots based on feel, and tweak the grind (and time the shots) as necessary.

I just remember that low volume shots should take longer, and high volume shots should take less time.

Excerpted from Al's rule: "...for every 10ml of espresso above 60ml, subtract 1 second of extraction time.....So, my 50ml ristretto should extract for 31 seconds. The 90ml lungo I make for my wife will need to extract for only 27 seconds"

I know these are just guidelines but is he really saying he can adjust his grind to get a change in flow rate of 10ml/sec (for a double)? That must require incredible finesse: the difference here between a 45ml ristretto and 90ml lungo is just 4.5 seconds! Then to be able to judge that by eye... However, if the practical part of the rule is this: fast pour stop short, slow pour stop long then that seems more feasible, at least to a newbie.

Anyway, thanks for the clarification Jim, I'll have to disassemble my grinder and adjust it internally to get it to grind finer than it does now, but if it works and improves the shots I'll post another video.

cannonfodder wrote:I knew the general idea of longer times for the lower volume but I did not realize that that much time was needed. I would have thought that bitterness from over extraction would be a problem.

I'm not very experienced at describing individual flavours in coffee (I'm still new to espresso) but in this case the shot wasn't bitter, more... sweet, reminded me of marzipan. Whether or not that is what it was supposed to taste like is another matter, I've never had a real ristretto.

Thanks for the continuing advice

DC

DC wrote:However, if the practical part of the rule is this: fast pour stop short, slow pour stop long then that seems more feasible, at least to a newbie.
DC

i dont really see anything 'newbie' about this. i do fail to see whats so complicated. its coffee, going into a cup. lol.

you have a cup that can only fill so much. the cups i use for singles hold ~1.5oz, for doubles, ~2.5oz.
if i know the total volume of the single cup is 1.5oz, and i want a ristretto, i stop it 2/3 full. if it takes 12 seconds, i get mad and adjust grind or use more fresh coffee. if it takes longer, i let it run without overextracting. i dont care if it takes 40seconds, it still comes out good. either way, i wind up drinking it, since i run a household, not a coffeehouse, and it gets expensive to always dump shots..

Well, we won't have to guess who just got their bottomless portafilter. So how'd it taste, and what was the adjustment mentioned in the video?

You beat me to the follow-up post. Work called, had in IT issue to take care of and got distracted by another thread.

This was the second shot using this blend so I am still chasing the grind and dose. You should have seen the first shot. I squirted the camera lens with a channeling jet. Complete melt down.

Play by play. I used a quarter pump to preinfuse (no coffee showing yet) then ran a full pull. The shot started off pretty good. A little center weighted but not bad. Nice coloring and even flow. Half way through the pull I wiggled as I shifted my stance. I am sure there was a flux in the pressure but I doubt that had anything to do with the shot's problem.

Three quarters through the pull the blonding started. If you look close you can see the beginnings of a couple of channeling jets. Small blond streaks suddenly appear and then disappear. That is the beginning of the end. After that some wholesale blonding and channeling appear. No jetting but you can clearly see the shot blow.

The shot tasted mediocre. I still got volumes of crema in the cup, quite dense actually. I had some nutty overtones with a little background fruit, pleasantly sweet but bitter in the aftertaste due to the blonding/channeling at the end of the shot.

Tomorrow I should have the grind dialed in (needs just a touch tighter). Then an adjustment in the dose and lever pressure to fine tune for the blend.

More to come.

another_jim wrote:The dwell time, that is, the time between turning on the pump and seeing the first drops, varies from machine to machine. **Do not** attempt to control this with tamp and grind, that won't lead to good shots. However, when using a vibe pump, by the time you see the coffee, you want the pump to have reached maximum operating pressure, which means that it runs quiet. In your pour, the pump stayed noisy for another six seconds. I would play a bit and see if the shots improve if you can get the visible flow to start at the same time the pump goes quiet.

Thank you, thank you, thank you...

I was extremely concerned about the dwell time. I have a Quick Mill Vetrano that I am just learning about and I could not get the dwell time longer than about 6 seconds. I kept making finer and finer grinds and all it did was make the flow of coffee come to a dribble and a shot pull at over a minute.

I think I have a good combination of grind and tamp now that I have this little tidbit of info. My bottomless PF is due here Thursday so I will start my video escapades to see if I can refine my skills and attain the perfect shot.

Thank you again for that little nugget of info. You saved my mountains of time and wasted coffee.

The Single, Revisited

You may need aspirin for this one as it's my first crappy attempt at video which I will improve but it shows the problems I have been having with stalactites that hang around too long. Another thing I noticed is very frequent "dead spots". I would have cut the extraction shorter but I didn't have a free hand so I let it go to the end of the programmed dose. Don't even strain to see the cup shot - it's too dark.

The pump was activated at the 2 second mark

Again, sorry for the quality and I will find a way to improve it with this little digital camera I am using.

Although the shot tasted good, I obviously would like to improve technique so fire away!



Edited to add: Vivaldi II machine, mazzer mini E and WDT used.

I just recently picked up a VII and haven't had too many issues on the pour side if I am careful with the dose and tamp. I get a pretty even start and a centered cone pretty quickly. It is real easy to overdose the S1. It looks to me like you are getting alot of channeling around the outer perimeter of the basket. The shot started from around the edges as well. Are you drying your basket before filling with coffee? A wet basket makes it tougher to get a good seal around the edge of the puck.

Cheers

Ian