Learning to love the Breville Oracle - Page 3

#21: Post by **caldwa** » April 22nd, 2015, 2:25 pm

Séb wrote: The stock portafilter is a double spout with a nice quality basket that looks very close in quality and finish to my VST. It looks like a 18g basket to me but the machine overdose it and it apply 30lbs of pressure when tamping. The PF weight 506g with the basket in place if you need that info. On the 8 tests that i did, i got one 21g dose, five 22g dose and two 23g dose. So we could conclude that the machine dose 22g +/- 1g. But i was playing a bit with the grinder setting but never more then two settings far apart.

I'm assuming you used the same coffee for each? What was the level of the coffee beans in the hopper for each test? I could imagine that having a greater amount of beans in the hopper (or less) could change the weight of the dose, give that the grind may be slightly different upon different bean weight levels in the hopper. For some coffees, the stock basket doses 24g! But mine is relatively consistent.

Séb wrote: Grinder setting 17 = 23g dose yield 30g espresso at 28ml plus the crema for a 77% BR
Grinder setting 18 = 22g dose yield 44g espresso at 40ml plus the crema for 50% BR
Grinder setting 18 = 22g dose yield 47g espresso at 43ml plus crema for 47% BR

So you see that the difference is important and too big to me for just one step on the grinder adjustment (after a complete purge of a full 22g dose to be sure the change was effective). The last test again at 18g was just to check the accuracy/repeatability. I also did the same at the grinder setting 17 and it was always very close so it is fine for repeatability i think. I also did some tests at setting 16 but the volume was way too short for such a large 22g dose. That mean that for my actual coffee blend with his 4 days old age, i need to stay in the 17/18 grinder setting and i can fine tune the total time duration for the blonding point. With the 22g dose, the 18 grinder setting is ok right now for me.

Now the shot took a total of 38sec which include an 8 sec pre-infusion. The first drop happen at 10-11sec mark. I think that for a 22g triple dose theses settings are fine. I could play a little bit with the total duration and pre-infusion in order to get exactly what i want to maybe help compensate for the steps of the grinders.

Was the shot time 38sec for all three shots? I pulled two ~21g shots in a 15g VST basket this morning on the same grind setting, and the first shot hit 40g in about 28s (with 5s pre-infusion at 55% pump pressure) and the second hit 40g in about 26s. Just an observation and not a test, but I find that the shot-to-shot quality consistency is pretty good when keeping dose in and dose out the same (where the time for each shot my fluctuate).

#22: Post by **Séb** » April 22nd, 2015, 3:17 pm

Same coffee blend was used, an espresso blend that i know very well. The hopper was full but on this machine i am pretty sure that the dose will not be affected by the quantity of beans in the hopper because the machine use the pressure on top of the coffee bed to determine the correct dose. That is why the dose will however change slightly if you use a different pressure at tamping.

Yes, the shot time was always 38 sec total including the PI of 8sec. I am very pleased with the machine but after all the tests i have done i still consider the dose versus coffee extracted in the same amount of time to vary a bit too much for my preference just by moving one grinder's setting to the following.

Just to be clear however, i agree that from shot to shot at the same settings it is very stable. But what i mean to say is if you change the grinder setting just by one number it affect the output too much, just like each step between the settings are too far apart. That is the only negative part i found out. I now have my Forte back home so i will make some tests with various settings, baskets, doses,etc...more cafeine to come

#23: Post by **angman** » April 22nd, 2015, 8:20 pm

Nixter is one person I spoke to that convinced me to buy the Oracle. Thank you