Help with first shots on Isomac Venus and Rancilio Rocky...

[Oenophile]

We got our Isomac Venus and Rancilio Rocky, and tried to make espresso for the first time. Just to warm up the machine and get a bit of practice, I used some pre-ground coffee that we used to use with our old Barista machine. These shots were thin, bitter, and awful. First attempt using the Rocky (on about 20) wasn't much better, and the shots were also thin and bitter. I dialed it down to about 14, tamped a little harder, and produced something with a little crema, but still light on flavor and high on bitterness. Dropped it down to about 9, tamped a little harder, and the machine took a long time to dribble out a little very dark, bitter espresso with no crema. Dialed it back to 11, used a little more coffee, tamped a little less, and had a decent shot, so we used that and added a little steamed milk for a small cappuccino. Still, it wasn't that much better than the old Starbucks machine.

So, now I have a bunch of questions. On a normal 58mm portafilter like this, how high should the coffee be once it's tamped? My best shot ended up about a 1/16 of an inch below the spring groove on the basket. Is this about right? And what's the best way to "dial in" the combination of tamper pressure and grind fineness? I tried using the 30 lb. pressure rule, but I think I may be tamping too hard? It's obvious that both the tamp and the grind affect the outcome, but is there a trick to getting pretty close? Also, if anyone else is using this combination, have you found a "sweet spot" with them? The Guatemalan Stumptown seemed to produce better shots (although without quite the sweetness we like) than the Caffe Umbria Bizzari Blend, which seemed to gum up the Rocky's chute when I tried to get it fine enough for an espresso (they were out of our normal favorite, the Caffe Umbria Gusto Crema Blend). Anyone have good luck with a particular coffee (preferably available here in Portland) with this combo?

Marshall

[jesawdy]

Marshall-

Lots of questions there (and to be expected).

I'll address a few. I hope a few Isomac Venus owners chime in on the machine.

On the Rocky - you need to find the zero point. Once you know the zero point, you can talk a bit more about particular grind settings (to a certain extent at least). Grind setting will vary day to day, bean to bean. My experience with Rocky is that the biggest grind changes are needed when you change blends or batches of beans, and only one setting change up or down day to day with the same batch of beans.

I emailed you some cleaning and zeroing instructions for Rocky. Once you know your true zero point, you can compare your grind settings to others; My zero is zero, and I grind from 6-11.... typically 8-9. At 20, you were most likely very coarse, you overextracted what it could and it was thin and bitter as you say.

Tamp pressure - you can try using a bathroom scale to feel what 30 lbs feels like. Or you can just pick a tamp level that you feel you can comfortably reproduce. Some folks say that the compression difference of the coffee bed at 30 lbs and higher isn't very significant, so one approach may be to err on the heavy side. I tend to err on the high side, I haven't had the scale out in a long time now, but 30lbs is less than I would've thought, I'm sure I have crept upwards in my tamp pressure.

Headspace of the shower screen and top of coffee puck - this varies from machine to machine. A rule of thumb is to have a slight impression of the shower screen screw after you've pulled your shot... or set a dime or nickel on top of the dry coffee puck and lock in, release and inspect the puck... shoot for a slight impression of the coin. Once you get some consistency on your grind/dose/tamp, you can explore this space a little bit and see what works best for you and your machine. For myself, on Silvia, a very small headspace is working good.

Okay, all that said, you need consistency, You will struggle a bit for awhile.... consistency will only come with practice. Review the Tamp and Dose Techniques Digest for some ideas on how to consistently dose, distribute and tamp. Also, you may want to try something like the WDT.

Good luck.