Hello! A long time lurker here. For a long time, most of my shots have a dead spot in the center for unknown reasons. The taste is sometimes good but ordinary most of the time. Over 15% of the time it is bland, bitter, and probably overextracted. The taste resembles what you get in *$ except that it has a nice and compact crema. Recently the percentage of bad shots skyrocketed to about 70%. I have no idea why and I am feeling incredibly frustrated. The coffee is freshly roasted by a specialty coffee roaster in Hong Kong. My espresso machine is Expobar Lever (HX) with a EricS-like thermometer and my grinder is dosered Eureka Mignon. I prepare the puck like this:

1. Grind the coffee to a ramekin.
2. Spoon the coffee to the basket.
3. WDT in the basket using a thin sewing needle.
4. Tap the basket to settle the grounds.
5. Use the back of a knife to fill in the low spots.
6. Tap again to settle the grounds.
7. Inspect the top of the puck to make sure it is even.
8. Tamp as hard and as flat as I can. (I think my dead spot in the middle is not related to tamping.)

I have tried the following to fix the problem. However, they all don't work.

• Instead of using the back of a knife to fill in the low spots, I tap and use Stockfleth for Dummies with a curved finger. After the Stockfleth, the center of the puck is depressed. I then tap and tamp. Tried five times and worked one time. However, the taste was bad.
• Switch baskets. I usually use VST but the problem persist with my stock Expobar basket.
• Cleaning the shower screen.
• Nutation.
• Fiddle with the grind settings. This problem disappears if I make it a 15 second gush (tasted horrible).

Here is one of my recent attempt. I prepare this puck normally, following the steps I had given above.
19.02 g in, 27.67 g out, a brew ratio of 68.74%. The taste is bland and bitter (taste overextracted to me, but I am not sure). The coffee was four day old.

EDITED: Added units in the last paragraph.

The whole extraction looks too tight. Either drop your dose or adjust coarser. It shouldn't take that long to form a cone.

Try Sherman's trick (I give Sherman credit, but I think he may have gotten this from someone else).

Use the rounded head of the handle on your tamper to make a dimple in the center of your puck after distribution, but before tamping, then tamp normally. The first time I did this I involuntarily scoffed and thought that there was no way this was going to help fix my dead spot, and then *waves wand* *poof* a beautiful extraction. You'll have to play with the depth of the dimple to find the sweet spot, but you should see at least a little improvement in your first go.

Lower your dose. Every time I see a doughnut of death extraction it is due to too high a dose. You do not mention any kind of weight and I cannot view the video from my current location. From your description you are overloading the basket.

UltramaticOrange wrote:Try Sherman's trick (I give Sherman credit, but I think he may have gotten this from someone else).

Use the rounded head of the handle on your tamper to make a dimple in the center of your puck after distribution, but before tamping, then tamp normally. The first time I did this I involuntarily scoffed and thought that there was no way this was going to help fix my dead spot, and then *waves wand* *poof* a beautiful extraction. You'll have to play with the depth of the dimple to find the sweet spot, but you should see at least a little improvement in your first go.

No.. Fricking... way.... Are you saying this is all I have to do?!

cannonfodder wrote:Lower your dose. Every time I see a doughnut of death extraction it is due to too high a dose. You do not mention any kind of weight and I cannot view the video from my current location. From your description you are overloading the basket.

When I lower my dose, I get a 10-15 second gusher which tastes horrible... I know this is probably down to my grinder, but its set as fine as it gets...

achipman wrote:No.. Fricking... way.... Are you saying this is all I have to do?!

Maybe. Worked for me when I was still using my Gaggia Classic. I've since switched to a Euro-Cuve tamper. Really what I'm saying is that it worked for me, it might work for you, ymmv depending on your grinder, humidity, manos, etc.

A few things: VST baskets are notoriously unforgiving. I get extractions that look kinda like that frequently (maybe not quite as bad, but similar), and they don't seem to impact taste much compared to prettier ones. WDT and careful distribution helps. Some coffees are pickier than others. I'm increasingly leaning toward relaxing and enjoying my coffee, regardless.

I agree that it looks a little slow in general, if you don't want to reduce dose try grinding a little coarser and see what you get.

And speaking of reducing dose, it may or may not have anything to do with your problem, but if you can't grind fine enough to get reasonable flow rate with a lower dose, you definitely have a grinder issue. Maybe you can recalibrate it to be able to grind finer? I would think though that even with your grinder as is you could find a happy medium between where you are now and gusher if you reduce dose only slightly.

Good luck.

Basically, no progress at all. For whatever reason, my grinder suddenly become 20 seconds coarser. I made 10 bad shots (drank eight of them) to adjust my grind (poor technique, I know ). Unlike Andrew (achipman), my grinder can grind fine enough to use 18.0 g of coffee but there is still a dead spot in the middle of the extraction. Does my extraction look very dark? Dan (HB) said in this post that WDT will cause very dark extraction that blond out early.

Alastair (UltramaticOrange):
The Sherman's trick don't work for me. I can't get the dimple right in the center with the correct depth. I am a rather clumsy person .

You need to make sure the grinds are distributed at the bottom of your puck. Most of the comments are focused on the top of your puck. Get a consistent method that allows for spreading of grounds at the bottom. Use a needle if you are really having trouble.

I WDT thoroughly with the needle lightly scratching the bottom of the basket so it shouldn't be a problem.