Slower shot time?

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Amos98

#1: Post by Amos98 »

Hey everyone,

My shot times were different this morning than they were yesterday morning, even though I did everything the same. Specifically, I pulled a shot yesterday on a Decent DE1 with a grind setting of 145 on a Bentwood Vertical 63 grinder and the shot took about 32 seconds (the previous shot was about 35 seconds at 141 a few minutes earlier). This morning, I pulled two shots at 145 again, and both took about 53 seconds. I didn't change anything today -- 18g of Monarch by Onyx Coffee Lab, RDT, ground directly into portafilter (18g +/- 0.1g), deep WDT with a Decent puck rake, tamped with a Force Tamper @ default pressure, and used a Bplus puck screen on top of the puck. Everything remained exactly the same, but for some reason, the shots this morning pulled much slower than yesterday.

Does anyone have any idea why this would happen?

Thanks, I really appreciate your thoughts!

GDM528

#2: Post by GDM528 »

What were the DE1 settings?
Water quantity added from RDT consistent?
Presuming, but gotta ask: puck screen thoroughly rinsed from previous use and inserted in the same orientation?
Puck raked til level?
Tap the basket to settle the grounds?
Rotate Force Tamper before compressing?
Exact same bag of coffee, and not close to bottom of bag?
Light/medium/dark roast?

This has me wondering if the DE1's control algorithms are too narrow and aggressive, e.g. allowing wild fluctuations in shot time in order to maintain the programmed pressure (or whatever you fixed), triggered by subtle variations in puck resistance...

User avatar
Jeff
Team HB

#3: Post by Jeff »

Can you provide a Visualizer link of the two shots?

Amos98 (original poster)

#4: Post by Amos98 (original poster) »

Thanks, Gary and Jeff, here are links to the shots (first link was yesterday and other two are from today):

https://visualizer.coffee/shots/55ef777 ... 3a767bebde
https://visualizer.coffee/shots/4c533b8 ... cab7e8dc47
https://visualizer.coffee/shots/97197f3 ... 1c52163641


As for the DE1 settings, I was running the stock Gentle & Sweet profile. I used the same spray bottle for RDT. I always thoroughly wash the puck screen with soap and water before using them again. I also place them with the Bplus logo facing up. I raked to make the surface as level as I could. I tapped the portafilter once to settle the grounds before removing the decent shot collar. I don't rotate the tamper before compressing -- iIve never seen this having an effect and from what I've seen from various people online, I didn't think rotating was necessary. It was the exact same bag of coffee. It's less than half used. Although I dumped the bag into a Fellow vacuum canister, so who know where in the original bag these beans were.

Thanks again!

User avatar
Jeff
Team HB

#5: Post by Jeff »

The second two overlay with each other quite well. It's hard to know just how well at such low flow rates (compared to what I know), but it looks like you're probably within 10% or so in the mass-flow over time. (The mass flow is "stepped" by about 0.1, balancing between smoothness and speed of response).

Overlay diagram, can time align as well as clicking "off" all but the mass-flow rate or possibly show just the mass in the cup
https://visualizer.coffee/shots/4c533b8 ... 1c52163641

There's a big shift from that first shot. Were the ones before that similar to it?

I'm thinking something shifted or changed in the Bentwood. Though it is a simple and robust mechanism, maybe something was "stuck" and then let loose, allowing the burrs to slide a tiny bit closer? I don't know.

GDM528

#6: Post by GDM528 »

I got some serious DE1 envy issues... Picture me standing at a traffic intersection, holding a cardboard sign that says "Will Work for DE1".

The different horizontal scales are kinda distracting, but one thing that jumps out at me is what appears to be significantly different pre-infusion outcomes. The earlier shots were likely visibly wetted, whereas the latter shots appear dry until 5 seconds into the pull - yikes.

When my shot prep is the same, a puck that's slow to pre-infuse is a better shot, so, congrats! I think it implies a more uniform puck with no sneaky channels - assuming absolutely everything else is the same. I start the pull once I see the liquid 'image' formed on the bottom of the basket and use that image to adjust how I pull the shot. If the DE1 doesn't have a wait-for-drips function I'll put my cardboard sign away.

What was the taste difference between the short and long shots?

GDM528

#7: Post by GDM528 »

Jeff wrote:I'm thinking something shifted or changed in the Bentwood. Though it is a simple and robust mechanism, maybe something was "stuck" and then let loose, allowing the burrs to slide a tiny bit closer? I don't know.
With my 64mm flat burr grinder (DF64) I've observed a significant shift in puck resistance based on the feed rate of the beans into the grinder. Is it possible for the Bentwood's feed path/mechanism to fluctuate the flow of the beans into the burrs?

Amos98 (original poster)

#8: Post by Amos98 (original poster) »

GDM528 wrote:What was the taste difference between the short and long shots?
Oddly enough, they were all drinkable. The short shot yesterday definitely tasted more acidic whereas the long shot tasted bitter, but not too bad. I was expecting it to be totally undrinkable, but it must have had a pretty even extraction.
GDM528 wrote:Is it possible for the Bentwood's feed path/mechanism to fluctuate the flow of the beans into the burrs?
From what I understand, the way the Bentwood pre-breaker system works is that it feeds the beans into the burrs at the same speed no matter how they initially enter the grinder, so I don't think this is the issue, unless the grinder is not working properly.
Jeff wrote:Though it is a simple and robust mechanism, maybe something was "stuck" and then let loose, allowing the burrs to slide a tiny bit closer?
This is what I've been worried about. I opened up the grinder a few days ago to check retention and calibrate. Everything looked fine. Maybe I'll open it up again and check to make sure I didn't leave a screw loose or something, but this seems unlikely given the simple design. Although it's always possible I screwed up some mundane detail.

Thanks again everyone.

Amos98 (original poster)

#9: Post by Amos98 (original poster) »

GDM528 wrote: The different horizontal scales are kinda distracting, but one thing that jumps out at me is what appears to be significantly different pre-infusion outcomes. The earlier shots were likely visibly wetted, whereas the latter shots appear dry until 5 seconds into the pull - yikes

This got me thinking. I actually did change one thing -- I gave two sprays for my RDT yesterday (fast shot), but only 1 today (slow shot). Could this have made any difference? It doesn't seem like such a slight change could have had such a large impact....

GDM528

#10: Post by GDM528 »

I RDT using a small spray mister, typically 3-ish pumps, shake-shake-shake the beans, drop into grinder and let it sit for a minute to let the static charge equalize between the grinder and the beans. I've never weighed the amount of water that I'm adding - but my descent into the depths of coffee nerdom is not yet complete, so perhaps someday I will ;)

For me, lighter RDT makes the grind appear finer-grained - but also stickier and more prone to pack/clump. Heavier RDT makes the grind appear coarser but also fluffier. The physics of how the water is affecting grind consistency and behavior is curious. Can't say if one is better than the other, but I'm learning to adjust WDT based on the RDT.