Lord Fluff wrote:
I'm pretty confident it's not technique. Partly as my half day on Robur/Linea went so well, partly as both me and my partner could easily get good shots from the setup in the past.

I wouldn't blow this off so easily. I have altered my technique every time I buy something new to get optimal results. Therefore, I wouldn't be surprised that what works on a robur and linea would not work at home. Those devices have a habit or minimalizing things that other machines are finicky about.

I can imagine coming home after this training putting to use what you learned and this didn't translate as well to your setup.

OF course I could be wrong but food for thought. Whenever I have issues its usually what I don't think it is and it takes forever to fix.

In the meantime I would put a gauge on your portafilter and see what the pressure reads.

Lord Fluff wrote:I know, it's driving me nuts....
The only way I can think to describe the results in terms of taste is - "not delicious". Crema tends towards yellow, not mocha colour. Flavours mostly are thin, bitter, sour.

So frustrating.

You might check the temperature of the machine. Sounds like it could be low and under extracting producing thin, sour, and astringent shots.

Any progress David? I'd recommend you to get a set of new burrs. Even if that is not the problem you'll end up with a set of spare burrs.

No progress at all sadly

Regards technique - I can only say that I'm doing exactly what I've done for years - measure 18g of beans, grind via doser flicking into PF basket, careful evening of distribution with a chopstick going upwards only, careful tamp til the click on the tamper, very gentle load into the group.

I didn't really learn any new techniques or change anything I normally do when using the Pro setup, it was more a day spent learning about coffee since (sorry if this sounds cocky) those of us on the course had pretty decent technique already. But more significantly I used to get good to great shots on this setup without really trying that hard in the past.

I'm sure it cannot possibly be the burrset. I changed this when I got the grinder a few years ago, and based on the amount of coffee I get through (2-4 a day) if I'd worn out a set of burrs by now then cafes would be changing them out every other day.....

Today's shots have been so far off it's not even funny -

Shot 1 - almost a blocker (grind unchanged since yesterday), eventual very slow shot, didn't even bother tasting it

Shot 2 - massive pull to one side, no flow at all over most of the rest of the PF, result drinkable (just)

I will see if I have a thermometer to check temperature - display says 95 but could of course be lying.....

I would just grind in basket, tamp and pull. cut out all the extra stuff for now and introduce them one at a time.

Then as others said, check the temp and pressure. Having too cold a shot will DEFINITELY produce thin and early blonding shots. Of course, if its too hot that can also cause blonding as it'll extract too fast.

Please determine the pressure into a blank portafilter, should be about 10 bars for a vibe pump and 9 for rotary. Which one do you have? What pressure reading are you seeing when pulling a shot?
Next the temperature is a little high, might try 93C for starters. For consistency, weigh the dose going into the portafilter, do not rely on putting 18g into the grinder and hoping to get 18g into the portafilter. Use the rated dose for the basket to start with. VST baskets are not hard to use but you need to be consistent with the dose. The problems you mentioned about one side of the protafilter is dead and the other flowing sounds like distribution. Some preinfusion can help this. Can you cause preinfusion with your machine? If so use low pressure to wet the cake and allow a few drops into the cup before applying full pressure. If weighing the cup, allow 5 grams into the cup before full pressure. If using a naked portafilter the preinfusion should coat the whole bottom of the basket evenly if the distribution/tamp is good.

Lord Fluff wrote:No progress at all sadly

Regards technique - I can only say that I'm doing exactly what I've done for years - measure 18g of beans, grind via doser flicking into PF basket, careful evening of distribution with a chopstick going upwards only, careful tamp til the click on the tamper, very gentle load into the group.

I didn't really learn any new techniques or change anything I normally do when using the Pro setup, it was more a day spent learning about coffee since (sorry if this sounds cocky) those of us on the course had pretty decent technique already. But more significantly I used to get good to great shots on this setup without really trying that hard in the past.

I'm sure it cannot possibly be the burrset. I changed this when I got the grinder a few years ago, and based on the amount of coffee I get through (2-4 a day) if I'd worn out a set of burrs by now then cafes would be changing them out every other day.....

Today's shots have been so far off it's not even funny -

Shot 1 - almost a blocker (grind unchanged since yesterday), eventual very slow shot, didn't even bother tasting it

Shot 2 - massive pull to one side, no flow at all over most of the rest of the PF, result drinkable (just)

I will see if I have a thermometer to check temperature - display says 95 but could of course be lying.....

Maybe a tiny pebble got in there at some point and damaged them enough to cause this change you are experiencing. Even by looking at the burrs you may not be able to see the damage. Obviously this is just a guess, but still very possible.

BTW if you say you haven't changed your technique and you used to get good results and you had good results with the Linea/Robur that you recently tried then I'm pretty sure the problem is not your technique. Even if technique was the problem you would still get at least a descent shot from time to time since you are not new to this. My money is on the Brewtus(temperature or pressure) or the burrs.

Bill - to address your points in turn....

Bill33525 wrote:Please determine the pressure into a blank portafilter, should be about 10 bars for a vibe pump and 9 for rotary.

Almost bang on 10 BAR (it's the vibe pump version)

Bill33525 wrote:What pressure reading are you seeing when pulling a shot?

Almost bang on 9 BAR

Bill33525 wrote:Next the temperature is a little high, might try 93C for starters.

I've been running it at 95 for as long as I can remember, I can try 93 for giggles; again my frame of reference is the previously excellent shots I used to obtain from this exact setup.

Bill33525 wrote:Use the rated dose for the basket to start with. VST baskets are not hard to use but you need to be consistent with the dose.

Baskets are rated as 18g. I actually weigh in 18.2g of beans which will usually result in almost exactly 18g of coffee. 0.2g of coffee either way is not the issue here I can tell you....

The problems you mentioned about one side of the protafilter is dead and the other flowing sounds like distribution. Some preinfusion can help this.

Bill33525 wrote:Can you cause preinfusion with your machine?

No, not as such. I could run the group with the PF held loosely below to just soak the puck. But why should every puck be screwy when I was getting textbook flow from the Robur/Linea, and have had good flow previously?

Right now I just want to stick the whole setup on ebay and start again.....

Hello Again-

Is there an espresso repair shop in your town or close by? Perhaps have a pro look at your setup?
Hope this helps.

To test the grind and make sure it's not your grinder you could buy some beans at a cafe and have them "espresso grind" a portion so you can test them in your machine - as quickly as you can get home. It won't be dialed in, but you can use it for evaluation purposes adjusting the dose as necessary to test the machine.

I don't see any mention of the thermosiphon in this thread. Have you inspected that path for scale or other issues? If the group isn't heating up evenly and properly you can get undertemp shots that will be all over the place in flavor, flow and quality. If there is enough scale in the line or the group heating area the thermosiphon might not work.

Another thing to test is the pump flow. If it's not even you'll get strange shots that way too. Without a load in the PF time water into a cup, and see if the second cup fills in relatively the same amount of time without turning off the pump. Testing the pump under load requires a valve on your PF spout, and I'm assuming we don't have those tools available for testing both at the same time.