SISC Junior Member Joined: 3 Mar 2013 Posts: 10 Location: Sullivans Island Expertise: I like coffee
Espresso: Mini Vivaldi II Grinder: Mazzer Mini
Posted Sun Mar 3, 2013, 9:38am Subject: Mini Vivaldi II Consistently Inconsistent
I have a Mini Vivaldi II with pre-infusion.
I typically pull 2 double shots--- one for my wife and one for me.
The first shot is always slower than the second, and the volume of the second shot is always higher, suggesting higher pressure on the second shot.
The grind is the same, technique the same, weight in the basket the same, tamping pressure with an Espro is the same. Even if it isn't, that fact would not explain why the second shot is a faster pour with higher volume every time.
Jmanespresso Senior Member Joined: 18 Jan 2009 Posts: 2,108 Location: Westchester NY Expertise: I live coffee
Espresso: Alex Duetto II Grinder: Compak K10 - Vario Vac Pot: Yama-SY5/SY8/TCA5 Drip: V60, Beehouse, CCD Roaster: Hottop B
Posted Sun Mar 3, 2013, 12:12pm Subject: Re: Mini Vivaldi II Consistently Inconsistent
Little bit of stale coffee left in the grinder that makes its way into the first shot. IF you leave the hopper with coffee in it, or if you single dose. Its more noticeable with coffee in the hopper, less noticeable if you single dose, but happens nontheless.
Solution- Grind a gram or three of coffee and discard it before you pull your first shot. "Problem" should go away immediately.
Follow Your Bliss
Coffee makes your constantly overcome your prejudices and re-evaluate your own "received wisdoms" when it comes to judging cup flavors. -Tom Owen, SweetMarias
SISC Junior Member Joined: 3 Mar 2013 Posts: 10 Location: Sullivans Island Expertise: I like coffee
Espresso: Mini Vivaldi II Grinder: Mazzer Mini
Posted Sun Mar 3, 2013, 12:26pm Subject: Re: Mini Vivaldi II Consistently Inconsistent
Wouldn't stale coffee have less oil in it, and produce the opposite result from what I am experiencing? Seems that the first shot would pour faster and with greater volume, not the second.
Keep in mind also that the Mini VII has volumetric dosing.
I don't leave ground coffee in the grinder doser. Any left over coffee is less than a gram. I appreciate your comment, but I am having a hard time understanding the theory behind it.
Further, I get the same result even if I do 2 shots, wait an hour, and do 2 more. Hard to believe less than a gram of coffee would make that much difference in that short of time period.
My previous machine was a Silvia, and I never experienced this issue, and I am not grinding any differently.
Posted Sun Mar 3, 2013, 12:44pm Subject: Re: Mini Vivaldi II Consistently Inconsistent
I had a similar problem with my VBM. I found that the first shot took longer to come up to pressure. I started using a blank basket to pressurize the boiler before my first shot and the difference between my first and second shot went away.
Jmanespresso Senior Member Joined: 18 Jan 2009 Posts: 2,108 Location: Westchester NY Expertise: I live coffee
Espresso: Alex Duetto II Grinder: Compak K10 - Vario Vac Pot: Yama-SY5/SY8/TCA5 Drip: V60, Beehouse, CCD Roaster: Hottop B
Posted Sun Mar 3, 2013, 3:40pm Subject: Re: Mini Vivaldi II Consistently Inconsistent
Ive experienced this exact phenomena on four differfent machines and four different grinders. Two E61 HXs, a La Spaziale Vivaldi II and the Alex Duetto, and the Grinders are two Mazzer Majors, Baratza Vario, and Macap MXKR(63mm Conical)
Ive pretty much always been a doser grinder guy. But, I weigh out beans per shot, add them to the empty grinder, grind them through, and then empty the doser completely into my portafilter basket. Thats how Im grinding currently, and thas what Im describing.
Walk up to my espresso area. I haven't brewed in 4 hours, and Im using the Mazzer Major in single dose mode. Looking at the grinder and the doser, its clean except for maybe a SPEC or two of coffee. Now, from here if I: -Weigh out 18grams of coffee, grind it, and empty the doser completely into the portafilter, the shot will pour how it will pour. Taste is slightly off because the machine has sat for a while(save that debate for another day), so I generally toss this shot anyway, but its not terrible. Little thin, little harsh, little bitter.. I can definitely do better. Weigh out 18 more grams. Grind em and dose em just like before. THIS shot will pour faster. Not majorly faster, but if the first shot was slightly i ristretto territory, the second shot is a solid normale. If the first shot was already normale, the second shot will be a bit too fast and underextracted.
This has been the case, on every machine and grinder combo I have owned. Now..
-If I was too grind through less than half a scoop of coffee and toss it, and THEN pull my shot, the first and second shots will be as similar as my dosing and tamping will allow.
-After a long idle period, if I walk up to my empty major, and turn it on, it will spit out a bit of coffee. Just a bit, .5grams at the most. The way the Vario is designed, I haven't seen this happen, and it most certainly happened on the Macap. The Macap would be sometimes a gram or more. But a flat burr mazzer will be around a half gram.
I think its not that its stale coffee slowing down the shot, but that its MORE coffee. When you single dose a mazzer flat burr, and brush the chute and dose the doser clean, you will get back exactly what you put in. I consistently put 18grams in, and 18grams out. IDK where that little bit extra comes from at the start of a session, but I know its there. Perhaps it is grounds that were previously compacted around the burrs or burr chamber and have came free over the idle period. There is also a slight amount of coffee ON the burrs, in the nooks and crannies.
And you might say that a half gram of coffee cant possibly be causing this issue. I say no way jose. Dial in a shot at 16grams on the nose. Then pull another shot, same grind same everything, but use 16.5grams. As much as .2grams can affect the flow of a shot, and half a gram is enough to be the difference between right on the money, and slightly off the mark.
I mean no disrespect, just trying to explain my theory. I am firmly convinced this is what is happening but if anyone has a different theory, I am open to it.
Follow Your Bliss
Coffee makes your constantly overcome your prejudices and re-evaluate your own "received wisdoms" when it comes to judging cup flavors. -Tom Owen, SweetMarias
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,018 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Sun Mar 3, 2013, 3:44pm Subject: Re: Mini Vivaldi II Consistently Inconsistent
Interesting. Well the mini is a vibe pump they ramp up in pressure and limited to grind and opv compared to a rotary that is set to pressure and is there in a moment and grind has little effect. Volumetric dosing, well not all are the same and I have no idea how spaz does theirs, volumetric dosing as I see it delivers 2oz of water to the group whether there is resistance or not so grind would have nothing to do with it, but this is the most advanced way to do volumetric dosing, most machines will not have this.
Personally I would go with the advice from purging your grinder of a couple of grams or what ever is recommended for your grinder and reinvestigate the problem. Next I would consider the pump, If it is ramping different from first shot to second it would give the results you are getting/
SISC Junior Member Joined: 3 Mar 2013 Posts: 10 Location: Sullivans Island Expertise: I like coffee
Espresso: Mini Vivaldi II Grinder: Mazzer Mini
Posted Sun Mar 3, 2013, 4:30pm Subject: Re: Mini Vivaldi II Consistently Inconsistent
I appreciate your reply, and I will try your suggestion.
However, I brush the intake thoat of the grinder after each use, and grind whatever is left in there. I also brush out the outlet, then turn it on again, then brush again. I then clear the doser. I have followed this procedure for years. The amount of left over coffee, as I said, is probably less than a gram---and it is likely to be distributed to both shots. Also, I never had this problem with the Silvia.
I therefore believe that the problem is related to the pump/valving/volumetric dosing system of the Mini VII. But again, I will try your suggestion.
I hope that someone with a Mini VII who has experienced a similar problem will chime in.he If I am the only one, then it must be a technique issue.
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