Ok, bought a scale tonight. Tomorrow I'll try reducing the dose down to, say, 16 g. (I've been using about 18) and see if that clears up some of the bitterness. Can I do that without having to adjust the grind? As I said, my shots are running a little long as is.

I'll experiment with it. My shots are running around 35 sec. with 18 g. It wouldn't hurt to run them a little faster, no?

Like I said, one notch on my grinder usually means a difference of 5-10 sec.

Dose is a separate variable from flow rate and volume. If you need to grind between steps, start at the finer setting, and halfway through the grind, turn it to the coarser. This is usually cheaper than buying a stepless grinder.

I have read some articles about making my grinder (Baratza Virtuoso) stepless, but I'm not sure I want to mess around with it. At least not until after the warranty wears out. Then, who cares?

k

So, I played around with a few different doses and grind settings this morning.

Up until now I've been dosing around 18g (I say around, because until I got the scale last night, I was just eye-balling it) and pulling fairly consistent shots. This morning I tried 14g and 16g. 16g. seems to be a little closer to the right ballpark. However, to compensate for the smaller dose, I've been grinding finer, which leads to clumping.

Normally, when I pull a shot at 18g. There's a slight impression left by the dispersion screen, but otherwise the shot has little evidence of any kind of channeling, etc., and the spent puck is dry.

When I pulled the shots with a lower dose, the shots channel and go very blonde at the end. The leftover pucks are somewhat soupy (moreso at 14g than at 16g.), and there are very obvious pits in the middle and channeling down the sides.

I've been using WDT. I knock the portafilter 5 times to settle the grounds then I tamp (actually measured tamp pressure this morning and I've been using around 70lbs, which I know is far too much), twist, NSEW tamp (much more lightly), then twist the tamper 2-3 turns without exerting pressure.

My thoughts on the channeling:

1. Could be caused by clumping, meaning I'm grinding too fine.
2. Tamping too hard.
3. Perhaps my machine just works better if you updose
4. There's something else in my technique that's contributing to this.

The last shot I pulled, I dosed at 16g. ground one notch finer, followed the usual method (only I tamped somewhere between 30-50lbs, rather than the usual 70). I heard the pump go to a higher pitched whir, It took 10 seconds for the first drop to appear. It took 35 sec to get 1-1.5 oz. The shot was a little bitter, but otherwise a very nice ristretto. Dark, rich crema, nice mottling, and speckling. Made it into a Latte that was almost as good as the one I had at Cafe Artigiano last week (Minus the rosette, but that's another thread maybe).

If I haven't said it already, thanks so much for everyone who's weighed-in on my various posts. I really appreciate you.

High dose pucks look prettier, but they channel a lot more at the start of the shot, which you can't see on your setup. Low dose shots can break down at the end of the shot, and start gushing, which is what you are probably seeing. Grind a little finer and pull less volume and a bit slower to compensate for the lowerd dose (the ratio of dose to water volume is one variable, the relation of dose to water flow is a second, the dose itself is a third -- you want to be able to adjust all three independently)

So, instead of dosing 16g and grinding at 5 and getting 1.5 oz in 35 sec, I should try 14g and grind at 4 and aim for 1-1.5oz. in 35 sec?

Does that sound right?

I've been reading Dave Stephens' thread about dialing a new machine, which addresses this.

Mostly, the timing stays the same (you should run the shot till it blonds, and not take that part too seriously in any case). But the volume of the shot, and the rate of flow should be kept in proportion to the dose. For instance, if you pull a single, it has to flow at half speed to get half the water volume in the same time. This sort of proportionality applies to all changes in dose.

"Darn it Jim! I'm a musician, not a scientist!"

I'm sorry, I just couldn't resist.