axboe Senior Member Joined: 8 Jan 2013 Posts: 8 Location: Denmark Expertise: I live coffee
Posted Wed Jan 9, 2013, 12:12pm Subject: Re: Problem with continuous shots on Simonelli Musica
Coffeenoobie Said:
I also notice a lot of movement in your streams, I believe you are getting heavy channeling. The first pull the right side sputters a lot. That is probably cutting down on your taste and crema. I am used to a lot of crema using a bottomless portafilter so your shots look very thin to me but that might be my fresh beans as well.
The beans I used in the video were freshly roasted this morning, so should be very fresh as well. But you are right, it does seem sputtery compared to the video you linked below. So if we focus on that, you think it's due to the tapping I do? That's easy enough to stop.
Coffeenoobie Said:
I also wondered how the first shot was good on an HX the others not. That also makes me question your temps and is part of what I wanted to see. Your 2nd shot crema looks very gold in the video, that also points to under extraction.
So if we assume the chanelling is due to the tapping, the under extraction is due to not tamping it hard enough? As you might have seen from the video, I'm using a Vario grinder. It's set between 1 and 2, so the grind should be adequately fine.
Coffeenoobie Said:
I believe you might have a 2 fold problem. Temp and channeling. You are drying the portafilter between pulls right?
I'm making coffee like a german, great :-). But thanks for the two links, I do see how my extraction is more like the 2nd one and not the 1st, though not quite to the same degree.
axboe Senior Member Joined: 8 Jan 2013 Posts: 8 Location: Denmark Expertise: I live coffee
Posted Wed Jan 9, 2013, 12:15pm Subject: Re: Problem with continuous shots on Simonelli Musica
calblacksmith Said:
Also, there are some other things here that threw the discussion a little off, namely you are using the wrong terms for what you are talking about. Some of this is the confusion that I tried to help with above with pressure but you also are talking about pods, pods are a pre ground dose of coffee, in paper wrapping. You place the entire pod, paper and all into a special porta filter basket that is designed for pods, no tamping, just load the PF and pull your shot.
Ahh, sorry, yes I was using the wrong terminology.
calblacksmith Said:
Your machine is a Heat Exchanger based unit. The temp is adjusted and maintained by a device called a Pressure Stat. It measures the pressure inside the boiler and cycles the heater on and off to keep the same pressure in the boiler. With a closed boiler, the hotter it is the more pressure there will be in the boiler.
You say that after it has been on for a while, the shot is good but the next is not. In your video, you did not do a cooling flush which tells me that your boiler is too cool, regardless of what the gauge says. The water from the brew group when first activated when the machine has sat idle for a while, should be too hot, it should flash to steam until the over heated water in the brew system is purged, this is only 2 to 4 oz or so and is not a big deal. For an idea about how your system works, I am cut and pasting from another post I made which explains how it works.
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,314 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Wed Jan 9, 2013, 12:27pm Subject: Re: Problem with continuous shots on Simonelli Musica
Dry might be an over statement but a wet spot is not good for even extraction. Any damp spot affect the way the water runs in the puck. If you watch good baristas they just wipe the portafilter down with a dry rag to remove the stuck damp grounds. I also really like my bottomless portafilter, it really lets me see if my puck is not perfect. I get sprites sometimes, mostly just micro sprites now but in the beginning.... messy pulls!
Even after a year of two pulls a day (4 on weekends) I am still not perfect but I believe that my pulls are better than anything you can buy in 25-50 miles range from my house.
Coffeenoobie
Buying advice: GRINDER GRINDER GRINDER. Don't cheap out on the grinder. My coffee treasure map... Click Here (maps.google.com)
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,661 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Wed Jan 9, 2013, 12:33pm Subject: Re: Problem with continuous shots on Simonelli Musica
axboe Said:
The beans I used in the video were freshly roasted this morning, so should be very fresh as well. But you are right, it does seem sputtery compared to the video you linked below. So if we focus on that, you think it's due to the tapping I do? That's easy enough to stop.
TOO fresh is not great either, you really should let them degas for a day or three, depending on the coffee. Too fresh and you get a lot of outgassing in the pull, which could be messing up the pull.
axboe Said:
So if we assume the chanelling is due to the tapping, the under extraction is due to not tamping it hard enough? As you might have seen from the video, I'm using a Vario grinder. It's set between 1 and 2, so the grind should be adequately fine.
When trying to trouble shoot a pull, you try to eliminate all you can first. A very common way to crack the puck and allow a way for water to get through in a stream (channeling) is to bang the PF on the counter, tap it with the tamper or disturb it loading it into the machine by having the basket too full and the puck hits the screen when you lock in. You should have a slight gap between the grounds and the screen. A U.S. Penny or Dime is about right more or less.
Tamping has very little to do with anything. All you are trying to do is to present a consistent resistance through the puck to the water. You can not tamp near as hard as the water pushes when brewing, 9 bar is about 140 psi (from memory) Under extraction is when you do not get all the flavor from the beans, this indicates you did not run the shot long enough or the grounds were too large to extract in the time you use to pull the shot.
Just be consistent with the tamp, some place about 30 pounds of pressure and all will be well.
axboe Said:
I am not! I have never realized that this is important. This is good, I'm learning :-)
Yes, you need to dry between the shots, a wet grounds basket can keep the puck from sealing against the basket and thus allows the formation of a place that may channel. ------------ reference to my post follows:
Your welcome. The more you understand how your machine works, the easier it is to learn how to use then fine tune it.
There is a screw adjustment on the Pstat, small movements can have a big impact depending on the make of the Pstat. Go slow and only make one change at a time.
Like I pointed out in the paste, the water in the HX system should be boiler temp if the machine has sat for a while. The water in the boiler should be hot enough to make a lot of steam, the hotter it is in the boiler, the larger volume of steam you get from the wand. This will also warm the water in the HX tube to the same temp so when you walk up to a machine that has been sitting for a while, you should get brew water flashing to steam for the first few seconds/oz. This water is too hot to brew with and you can scorch the ground coffee, ruining the taste. It seems that you do NOT flush for your first pull, give it a try and if you get little or no steam from the group head (no portafilter in place) then the boiler is too cold. A warmer boiler will also have a higher reserve heat factor thus causing the water in the HX system to warm faster so you can pull the shots closer together and still have good heat.
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Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,314 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Wed Jan 9, 2013, 12:46pm Subject: Re: Problem with continuous shots on Simonelli Musica
I assume that your Musica has the same pstat I have. It takes a full turn to move the temp you will see the +- by the yellow thing you have to move to get to the adjustment screw. The musica has a better thermosiphon than my Oscar, (something I hope to fix in mine in the next few weeks) but I believe you still need a short cooling flush before the first pull of the morning. (an oz or 2) After that it should rebound while you are grinding the next shot. That is why I was looking at the videos. But neither person did a cooling flush that I saw but I have no idea how much it was used before the camera started rolling. I would research this if I were you, you might not need a flush but I don't know, my Oscar is one model below yours but a lot of the same guts are in both. I clearly need a flush, steamy hot water comes out if it has been sitting a while. And I feel like you should have steamy water or water right below the steaming point if yours has been sitting a while too even with the better thermosiphon. But I don't have your machine so I am not 100% sure.
I watch the water and see what is called the water dance to judge the temp. When it is right the water settles down to a steady stream. Before that it sputters and spits and may have steam if it has been sitting a long time. I drain 4-6 oz out before I pull my first shot of the morning. I put some in my measuring shot glass and some in my cup and it warms them. If there is a good sized gap between pulls I might only drain off 2-4 oz before pulling the next shot. If I am doing shots as fast as you were I would only drain the first shot and not the others. If Oscar is busy he is not over heating. A bored Oscar is an over heated Oscar.
NS should be able to tell you if it needs a cooling flush first thing. I am pretty sure it needs a short one if it is sitting doing nothing. (2-4 oz)
Coffeenoobie
Buying advice: GRINDER GRINDER GRINDER. Don't cheap out on the grinder. My coffee treasure map... Click Here (maps.google.com)
Sorry for the late response, but I had some travel which both prevented me from posting and brewing! Anyway, I went through the suggestions, and what worked for me, was to do a proper cooling flush before brewing. The shots are better now, and more stable.
Another thing that influences the shot variance is the coffee being used. As mentioned earlier, I roast my own as well. So I tend to use different beans, even mixes of them. I have some favorite ones I use, and then I experiment with new ones too. What I've found is that if the coffee is roasted too lightly (new mixes of coffees, sometimes I'll "ruin" one), then I very easily get channeling. Not sure why that is, to be honest, but experimentally I've deduced that this is why that sometimes happens. If it's roasted too lightly, then I get too high volume and light crema for every single shot pulled.
Oh, and I also dry the portafilter before use to avoid channeling. That was another great suggestion in this thread, something I didn't realize before.
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