spromance wrote:I'm pretty surprised though that a coffee as dark as you describe can't shatter finely enough on the finest grinder setting to choke the machine at a 16g dose.

bergerb wrote:I always thought that light roasts are easier to brew, because they extract nicer flavors at higher ratios (like 1:2 or 1:3, which would be achieved with a coarser grind)?

Sorry for any confusion: instead of discussing whether a light/dark roast's desirable flavors are easier to extract than the other, I was trying to refer to how they grind / shatter apart. Dark roasts would tend to produce more fines and an overall finer grind for a given grinder setting (i.e. the finest you can go on the Express grinder). In that sense, I was just surprised that a dark roast at the finest setting wouldn't be able to slow the flow down enough for you to hit the weights and times you're aiming for.

bergerb wrote:The pressure is still too high, I tried screwing out the OPV some more, but ended up just turning it a half turn (so now I am at -2,5 turns), because it got pretty wiggly and I don't want it to leak. My conclusion is that (at least on my machine) the OPV is simply not made for such low ratios

How's it taste compared to a shot from your La Pavoni? Not to discourage continued experimentation, but if the taste is where you want it, I wouldn't be too concerned with being 'over' on the gauge. If you're hitting the weight and time targets you're after, and it's over or under extracted, you could also still look to compensate with temperature lower or higher.

Thanks for the heads up about the clip! Will keep it in mind if I'm ever think about lowering mine again, as I don't want to go so loose that there's spillage internally.

spromance wrote:Sorry for any confusion: instead of discussing whether a light/dark roast's desirable flavors are easier to extract than the other, I was trying to refer to how they grind / shatter apart. Dark roasts would tend to produce more fines and an overall finer grind for a given grinder setting (i.e. the finest you can go on the Express grinder). In that sense, I was just surprised that a dark roast at the finest setting wouldn't be able to slow the flow down enough for you to hit the weights and times you're aiming for.

Thanks for the clarification, I get it now

spromance wrote: How's it taste compared to a shot from your La Pavoni? Not to discourage continued experimentation, but if the taste is where you want it, I wouldn't be too concerned with being 'over' on the gauge. If you're hitting the weight and time targets you're after, and it's over or under extracted, you could also still look to compensate with temperature lower or higher.

My last shots were pretty close, I think I can improve a little bit with my distribution techniques, sometimes I get some nasty channels..

I am using a dosing cup with my La Pavoni (actually the bottom part of a Porlex Hand-Grinder.. fits perfect), that I shake around a bit - that breaks down the clumps. This is fast and absolutely not messy (I am currently spilling coffee grounds all over the place)
With my Barista Express I am currently using the back of a spoon to stir around the grounds.. didn't find the right cup yet (which is not expensive ..)

But I am currently getting my weight and time targets and I think the OPV Adjustment improved it a lot

Oh and there seems to be a smiley limit : o

Thanks for all of your help

Benjamin

Alright, so now I am bringing out the big guns, the last few days I got the extraction right, got no channels and I'm still not satisified.

My explanation of the gauge:
It is a 20bar gauge, with a different Template. If you extend the Labels of the gauge, you get close to the 20bar mark on 20bar gauges (picture)
I will verify that with a portafilter pressure gauge.


My OPV is screwed almost all the way out, so I am going to install a better one with a wider range of adjustability.

Do you have any suggestions which OPV to choose? Has anyone done this yet to any Breville/Sage espresso machine?

Benjamin

//EDIT: Alright, nevermind, found enough threads in the internet I'll keep you updated

//EDIT2: I think I will go with the Exobar E614 (I dont know if I can post a link here, but I found a tutorial. If you google this OPV and Breville, I am sure you will find it)

Short update, got a pressure gauge and an adapter from 3/8" to 1/2". Doesn't fit that well, but works to prove my theory

http://www.youtube.com/watch?v=_PT-pxP61Hs

OPV mod follows on the weekend

New owner of the Barista Express here. I'm new to the machine and the wonderful world of home espresso. Why are we so concerned about the OPV and what the pressure reader says? If we get our shot in the right dose, yield, and time - isn't that pressure reading unimportant. Or does that pressure reading effect the extraction process? I'm a little confused. I've noticed that my usual 16.5g in/ 25g out in about 26 seconds reads pretty high on the meter. Fooling around and messing with grind size to get the meter into the 'espresso range' resulted in a reeeeeeally quick shot.

You are experiencing exactly what I did

I don't exactly know how much the pressure affects the extraction, but my coffee tastes still a little bit bitter and I ran out of options..

There are basically two types of pumps, cheaper vibration pumps (loud) and more expensive rotary pumps (not so loud). You find a lot of information on the internet about those pump types, but the main difference is, that the vibration pumps does not limit the pressure. Thats why they need an Over Pressure Valve.

So if you grind very fine and want to achieve eg. a 1:1.5 ratio, the vibration pump will produce a lot more pressure (compared to a ratio of eg. 1:3) (for me around 15bar, factory-opv-setting).

So if you have a sh**ty OPV, you are basically limited in the range of ratios you are able to produce, because if you change your ratio, you have to adjust the OPV accordingly (to produce exactly 9bar).

And this is why I am changing the OPV: to get a wider range of OPV-Adjustment (a wider range of ratios)

(At least this is my explanation, please correct me if I am wrong )

Do you think I should look into adjusting my OPV?

I dont know, if you are happy with your coffee now, I would not change it. If you are not happy with your coffee, first try altering easier-to-adjust settings like temperature or play around with the ratio.

If you are new to the espresso world, I would suggest to learn as much as possible about coffee and your machine, before you mess around with your machine

Alright, operation successful, got the tumor out

I was waiting for the teflon tube, because I didn't want to cut the old one.



Parts used:
1/8 inch to 4mm tube adapter
Expobar OPV (E614)
4mm teflon tube with Breville Fitting Thingy

I ground off the lower threads of the new OPV to match the thread-length of the old OPV and also the upper threads, so the 1/8 inch to 4mm tube adapter has more thread-contact, as the inner threads don't start at the top-edge of the new OPV.

I then grabbed the o-ring of the tube adapter and put it on the lower threads of the new opv, put some teflon tape on the tube adapter and screwed everything back together.

I also had to remove the upper mounting screws of the pump to screw the OPVs out and in.

Pressure now looks ok, is between 9 and 10 bars. I will post a video, when I get it dialed in perfectly

Alright, now with my Mignon grinder, got it fine enough and pressure stays at 9 bar
The Barista Express Grinder is just not made for less than 1:2...

http://www.youtube.com/watch?v=fK5d2EQJB0Y