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What can cause variable puck expansion - Page 4

Postby shawndo on Sun Jan 06, 2013 2:27 am

I recorded a couple of shots. I've tried different grinders and baskets, so the it's only espresso machine or barista that hasn't been eliminated as a possible problem. Please take a look and comment on which it might be...

(Sound is a little loud, might want to mute the video)

Shot 1 is 18g in an 18g VST



Shot 2 is 18g in a 22g VST

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Postby Peppersass on Sun Jan 06, 2013 4:44 am

What is the coffee you're pulling?

What beverage weight are you pulling?

Can you do a couple of videos with the Robur for comparison?

I saw two spritzers in the first video, but none in the second. In both videos the pull goes very blond for too long before you cut it. Looks like you should be grinding finer. That might take care of the spritzers, too, which can happen sometimes when you grind coarse and fill the basket to capacity.

I wouldn't worry about the multiple streams. That's typical with VST baskets.

However, you're getting a bit of a halo extraction, which means the coffee is less dense toward the edges of the basket. Try a NEWS and/or nutating tamp before the final tamp.
Dick Green
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Postby cpreston on Sun Jan 06, 2013 5:27 am

FWIW I have found that a rubber band stretched between the arms on the M3 will hold the basket in place hands free.
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Postby frank828 on Sun Jan 06, 2013 5:31 am

first thing that came to mind was how fast the flow started after you started the pump. i'd also suggest grinding finer. *just watched the second vid, flow started like 1/2 to a second slower. see if slowing it down even further would help.

also, like peppersass asked, how much beverage weight?
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Postby bmb on Sun Jan 06, 2013 6:16 am

By Scott's Rao book I would say that your shots are channeling, getting a little more yellow on one side before the others.
For my taste, the baskets you're using are too small for all that coffee ...
It seems to me that there may be left too little room for PI ...
I would use less coffee or get bigger baskets.
The Espresso Resource 18 and 21 gr baskets (I prefer ridgeless) work great for me. I take the 21 basket whenever I use over 17gr of grinds.
I wouldn't use either the funnel neither the hand for distributing, and would WDT with a toothpick, that needle feels much too fine.
Could eventually try the funnel, to dose into the basket, without holding it so near the grinder, just resting the basket in the table with the funnel on feels "better" to me (it's, just as I said, just a feeling).
Also your grind's looks "sticky" to me ... Mine looks "drier" ...
Perhaps the roast may be a little too dark or oily ?
My routine is:
1. Grind and dose into the filter.
2. Tap filter slightly on the rubber mat (one or two times from 1 - 2 cm high), just to accommodate the grinds, pre-leveling.
3. Distribute grind evenly with toothpick, eliminating eventual clumps, and allowing the grinds to level all the surface.
4. Repeat tap (as in 2). Now the surface should look smooth and leveled.
5. Tamp, as you do the first part of yours, just leveling and pressing with the fingers, may slap harder (as in OE's slap technique video) against the rubber mat. In this "diagnosis" phase, I would avoid pressing harder, as you do in the second part of your tamp, as you risk "breaking" the leveling already done.
6. I avoid touching the grinds with fingers or hand, also tamping too hard (making force may take your arm a few degrees from the vertical, without noticing it), and woudn't polish, as it might disturb the puck.
7. Extract.

I hope that some of these "alternative handlings" may help you find out what is going wrong with your shots.
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Postby shawndo on Sun Jan 06, 2013 9:06 am

Peppersass wrote:What is the coffee you're pulling?

What beverage weight are you pulling?

Can you do a couple of videos with the Robur for comparison?



I went back to Stumptown hairbender after i found that the same thing was happening with other beans. bev weight is right around 30g. I shoot for a .60 ratio.

If I grind more fine, then the flow won't be right. I'll try and dial in the Robur today, but I might need to pick up a few more bags of coffee.

It's good to know that multiple streams are typical with VSTs. Once I figure out my issues, I'm switching to a spouted PF so I won't have to obsess and look at it.
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Postby erics on Sun Jan 06, 2013 10:23 am

I'm switching to a spouted PF so I won't have to obsess and look at it.

Try a single spout PF and watch (uh oh, bad word :) ) the stream as the shot progresses. As the liquid loses its surface tension characteristics the flow will look like a snake.

Obviously, stop the shot the moment this is sighted.
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Postby shawndo on Sun Jan 06, 2013 7:25 pm

A couple of Robur E shots. One with WDT and the other without. Both are 18g in an 18gVST. I also switched the screen to the sproline one with the lower profile screw. (I did a few shots before I switched it and there was no difference)



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Postby frank828 on Mon Jan 07, 2013 3:57 am

what do you mean the flow wont be right?

those last two videos, i think the first drops come waaay too fast. seems to be barely 3 seconds from when you start the pump. i'd definitely grind finer.
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Postby _bm on Mon Jan 07, 2013 11:28 am

Hi

I would omit the firm tamp after (a slightly more intense) nutation so that the coffee bed stays more dense at the side than in the center. That's what I am doing fighting side channeling...

Regards
BM
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