Cafelat with Timemore Slim Plus - Page 4

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Veganpotter (original poster)

#31: Post by Veganpotter (original poster) »

jpender wrote:That's something that you ought to figure out, regardless of the amount of water you decide makes the best cup. Extra water should have no impact on the permeability of the puck. So it's due to some side effect of adding more water, not the water itself. Whatever is going on it's unusual. I would bet it would be obvious if someone here could see what you're doing.
Yup, it doesn't make a ton of sense or any really :D I definitely pour slowly and move the landing location so I'm not getting excess pressure on one side of the shower screen.

Veganpotter (original poster)

#32: Post by Veganpotter (original poster) »

I tried a shot with the paper filter under the puck. I definitely stayed over 6-7 bars over about 25 seconds. But I also lost the qualities I love of not having paper filtration. So paper under the puck is a no-go. Someone commented on the forum a while ago about wishing there was an ultra-fine screen. I'd totally pay for one if it were available.

*I also tried a 19g shot later that stayed over 5 bars and was pretty decent. I'll try 20g in the morning but I don't really want to have to pull huge shots to hit high pressures.

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Jeff
Team HB

#33: Post by Jeff »

A video, at this point, would be very helpful. A photo of a pinch of your grinds spread out in white paper and a mm or sharp inch ruler might help too.

Judokus

#34: Post by Judokus »

jpender wrote:Extra water should have no impact on the permeability of the puck. So it's due to some side effect of adding more water, not the water itself. Whatever is going on it's unusual. I would bet it would be obvious if someone here could see what you're doing.
The air pocket above the water will influence the pressure built up when pulling the levers. Since air is compressible the force on the lever will not directly translate into pressure. So if fully filled with incompressible water the puck might be compressed too aggressively in the beginning. With my Caravel I can tell from lever feedback when some air is still trapped above the water.
Apart from temperature only for this reason I would recommend to use as much water as possible. May be try a Mord gentle pressure ramp up then.

Sib

#35: Post by Sib »

Veganpotter wrote:I've even tried tamping with a good 100lbs of force and it makes little difference from the typical 30ish pounds.
Have you tried a (much) lighter tamp?

I had a similar problem, which I also tried to solve by tamping harder and harder. After looking at the Cafelat Robot video uploaded by Cafelat, however, I came to the conclusion that perhaps I was tamping too hard.

When I tried an extremely light tamp, suddenly the resistance in the puck increased manifold!

jpender

#36: Post by jpender »

Judokus wrote:The air pocket above the water will influence the pressure built up when pulling the levers. Since air is compressible the force on the lever will not directly translate into pressure. So if fully filled with incompressible water the puck might be compressed too aggressively in the beginning. With my Caravel I can tell from lever feedback when some air is still trapped above the water.
The force to pressure relationship is always P=F/A, regardless of how squishy it feels. Air affects the travel of the lever(s). If less air results in greater puck compression or briefer preinfusion wouldn't you expect that to decrease puck permeability?

mikelipino

#37: Post by mikelipino »

Maybe it's the difference between statics and kinematics? While the pressure equation is right any any point in time, there's a lot going on during a shot that can change all the variables. Just as a mental model, it's possible that a looser tamp and slow ramp of pressure (either intentionally through preinfusion or with the larger air cushion) would allow grinds (especially fines) to migrate to spots of higher flow in the puck and work to normalize flow across the puck. In highly tamped and quick pressure build shots, grind migration would be more limited, and only water would be able to travel to high flow spots and channel.

This has all the earmarks of a linear algebra problem if the above is in the ballpark. And I'm too far out of school to even attempt it! :D

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jpender

#38: Post by jpender »

Modeling puck dynamics sounds really hard. But trying it is easy. Who hasn't done this with their Robot?

I've never had a gusher due to high fill height or bringing the hammer down immediately. Never.

Judokus

#39: Post by Judokus »

jpender wrote:If less air results in greater puck compression or briefer preinfusion wouldn't you expect that to decrease puck permeability?
Yes, that would be my expectation. At the same time, the reduced puck permeability (or increased flow resistance) might increase the risk if uneven extraction and/or channeling.
Again, from observation with my caravel, I get much better and consistent results if I increase pressure above moderate preinfusion only after drips built below the whole filter screen. And then also a moderate pressure ramp up helps to engage a nice steady Extraktion. The pressure (from lever feedback) doesn't feel smaller then. Although the puck might feature less resistance which might be compensated by higher flow.

jpender

#40: Post by jpender »

Judokus wrote:Yes, that would be my expectation. At the same time, the reduced puck permeability (or increased flow resistance) might increase the risk if uneven extraction and/or channeling.
Okay, maybe bringing the hammer down quickly could increase the risk of unevenness/channeling. But the OP is describing a 3-4 bar shot.