I recenty scored a second group handle for my Breville Cafe Roma (about 8 years old now) and turned it into a naked handle so that I could see the extraction and how 'bad' my tamping etc has actually been. I was kind of suprised to see that it wasn't as bad as I had imagined it might have been with not too much channeling that I could see.
I have noticed that it's starting from the outside and taking a good few seconds to hit the centre of the basket however. I have tried to be consistent with my tamping. I'm using a EM480 grinder and Merlo Beans. The beans are a couple of days ole sitting in the hopper which I know isn't ideal, but I can't bring myself to toss them as I can use them for practice as a worst case.
Anyways, I have converted the baskets to single layer and it seems to hold 16 grams when settled, scraped flush with the top of the basket, NESW light tamped, then relatively heavily tamped.
I am still using the black plastic tamper, but will be looking to purchase a 51mm flat faced tamper very soon to try and get some more consistency.
You can see some channeling coming through about midway through the extraction. I have also noticed I get a more 'foamy' Crema with the naked, but have seen mention that this might be due to the extractio not hitting the metal group holder before dropping to the cup.
Any suggestions or suggested reading to improve this?
Thanks in advance.