A view from the top.

[Tex]

But those were from '04-'06, they've changed their tune since then.   

Rule of thumb a) "puck expansion during the pull is a given, but there needs to be some headspace before the expansion occurs."

Rule of thumb b) "taste of the espresso trumps rule of thumb a)."

Before is the operative word there Peter. The top of the puck should not come in contact with the screen or screw when the portafilter is inserted.

[Tex]

After I pull a shot with a Gaggia I check the puck. There should be a divet from the shower screen screw, and a slight impression from the outside edge of the shower screen holder plate.
 
 Anything other than these impressions in the puck indicates problems with  distribution techniques.

I suspect because you have problems with your distribution techniques you are updosing to compensate.

You suspect? I thought you'd read something, somewhere, that said I was incorrect?

I just present the facts as I see them - folks can argue with them if they wish. I also presented the opinions of others - folks can argue with them if they wish.

Where's that brass billy goat animated GIF?

[EricBNC]

I just have a different opinion.  Your grounds look different than what I see at the end of my shots. The particles look much larger in your wet basket shot - mine are like fine silt.

Here is some old world old school thought recovered from H-B:

Marino Petracco in Espresso Coffee, 7.5.4, Illy & Vianni, eds wrote:

"During expansion, wet coffee grounds exert a pressure comparable to the wooden wedge once used to split marble ... On account of this behavior, an empty space is left above the ground coffee cake inside the extraction chamber. The actual expansion of the coffee cake varies by blend, roasting degree, and dose, and determines the minimum headspace (around 5mm to 6mm) needed to prevent over-compaction."

[Tex]

I just have a different opinion.  Your grounds look different than what I see at the end of my shots. The particles look much larger in your wet basket shot - mine are like fine silt.

Here is some old world old school thought recovered from H-B:

Marino Petracco in Espresso Coffee, 7.5.4, Illy & Vianni, eds wrote:

"During expansion, wet coffee grounds exert a pressure comparable to the wooden wedge once used to split marble ... On account of this behavior, an empty space is left above the ground coffee cake inside the extraction chamber. The actual expansion of the coffee cake varies by blend, roasting degree, and dose, and determines the minimum headspace (around 5mm to 6mm) needed to prevent over-compaction."

When you can't argue the facts, just argue - right Eric? Nothing you quoted contradicts what I said. I'm done with this thread if all you're going to do is grasp at such weak straws to further your specious contentions.

BTW: What happened to all those examples of what you read?

[EricBNC]

Sounds like you are attacking the messenger instead of refuting the message - good to know then that my facts are solid. 

Tighten your grind a bit and you will be fine.

[Tex]

Sounds like you are attacking the messenger instead of refuting the message - good to know then that my facts are solid. 

Tighten your grind a bit and you will be fine.

Like I said, "Nothing you quoted contradicts what I said."

On account of this behavior, an empty space is left above the ground coffee cake inside the extraction chamber.

This means leave a gap between the dry puck and the screen. After the puck is saturated it will expand, filling the void in a properly dosed puck.

I'm still waiting for any links to anything that contradicts what I said?

[EricBNC]

Because I care - and because I want you to have the best espresso possible I give you some reading:

http://www.home-barista.com/tips/what-about-overdosing-makes-channeling-more-likely-t5373.html

[Tex]

Because I care - and because I want you to have the best espresso possible I give you some reading:

http://www.home-barista.com/tips/what-about-overdosing-makes-channeling-more-likely-t5373.html

Come back when you've enough experience to comprehend what's being said in that thread.

[EricBNC]

That is a childish thing to post, Tex.

[staylor]

After I pull a shot with a Gaggia I check the puck. There should be a divet from the shower screen screw, and a slight impression from the outside edge of the shower screen holder plate.
 
 Anything other than these impressions in the puck indicates problems with  distribution techniques.

How about this...

Tex, it's nice that you have a routine after you pull a shot on your Gaggia. It's nice that you think there should be a divet and slight impression after you pull a shot on your Gaggia. It's nice that you think when you pull a shot and check your puck that if there isn't any divets or outer edge impressions that your distribution technique was incorrect.

It's nice that your opinion is just that... your opinion. It's also nice that facts are different than opinion.

Your technique applies to you. It doesn't apply to me, or a lot of people.

[John F]

A view from the bottom.   

[Ray T]

Looks like your puck is smiling John must have been pulled Naked