Silvia V3 + PID, Vario ceramic grinder
Grind: 17-18g, ~2-I on Vario
PID: 1.2s pre-infusion / 2.5s saturation / 25s extraction

Typically, this results in 30g of yielded espresso. That is just one shot. Should 18g not yield a double?

Most often, we have to pull several shots, and less often the shots pull the full 25s before the stream becomes pale-to-almost-transparent.

And help?

Er, how does it taste? For what it's worth, I start with a brew ratio around 70% and adjust to taste from there. See How to Adjust Dose and Grind Setting by Taste and Brewing ratios for espresso beverages.

Are you expecting less, or more? 30g of liquid out of 18 g of coffee in 25 seconds sounds pretty reasonable to me. That's a pretty big shot, right on the border between normal and lungo territory according to our brew ratio chart that HB helpfully linked to. I would generally prefer to tighten up the grind and yield a little less, but it depends on mood and the coffee. As long as you're in the ballpark there is no "right" answer.

Pardon my math fail, that's more on the ristretto side than the lungo side. Which sounds even more reasonable, that's the range I usually operate in. If you think you're getting premature blonding you can try WDT or some other technique to make sure your distribution is good, otherwise you're in the ballpark, just adjust to taste.

Well, when it comes out right, it is good. Though it is pretty hit and miss. The other night, my wife pulled a beautiful shot. Even distribution out of both spouts (normal PF) and perfect timing. So she pulled another and it came out way too fast. *shrug* Not sure what happened there. It could only have been the tamp, but I'm not sure.

Other times we have pulled ten shots and not a one was the same. Sometimes it'll extract faster, despite having increased the dose or using a finer grind. Really not sure.

We have read the guides. "/

Your main variables are grind, dose, and distribution. Your grind requirements will change as the hopper empty and less pressure is put on the beans. You might consider single dosing initially to limit this variable, or just makes sure your hopper is always fairly full.

Make sure your dose is consistent. If you're really varying from 17-18 grams, that's a little too much variation, try to control it tighter than that.

If you know your dose and grind are consistent, and your shots are still varying, you're probably having distribution problems causing channeling. A perfect distribution will flow much slower than one with even minor channeling. Bottomless portafilter is the best way to verify this.

Perfection is a never ending journey, but you will gain much more consistency with practice.

It's probably cold comfort, but you're not alone in reporting inconsistency issues with the Rancilio Silvia. It's part of its charm. Other than the usual fastidious attention to dose and distribution, there's some Silvia-specific suggestions if you search the forums (e.g., poor man's preinfusion from the Rancilio Silvia Review, lower brew pressure, allowing plenty of headspace).

uRabbit wrote:Typically, this results in 30g of yielded espresso. That is just one shot. Should 18g not yield a double?

The term "ounce" is used for both weight (16 ounces in a pound) and volume (32 fluid ounces in a quart). You are most likely confusing the two. It's true that 30g is approximately one ounce, by weight (but not volume). Espresso extracts as crema, which is only about half as dense as liquid water. I typically extract 45-50ml liquid volume, but the weight is only 22-24g.

In general, your best bet is to ignore any sort of volume measurement and concentrate on brew ratio:
weight of coffee grinds (in grams) / weight of extracted liquid (in grams)

We have been using HB's Espresso Guide as a rough outline. There it says that a double is 16-20g, and I have read that a single is 30mL while a double is 60.

And yes, we only put beans in the hopper after measuring them to the tenth gram.

I will check out those links.
We only record in grams. So I guess we're doing well enough. 18g giving out 30g of good brew is good, but I'm not sure how to reproduce that.

I just pulled my best shot ever.

Vario 2-J
Same PID settings
18g produced 25g (both exact) = 72%
edit: 201°F
Came out evenly.

This is pretty awesome considering that my wife is usually the one to pull.

Now I will pull a second shot to see if I can replicate it. Edit to follow.

EDIT: Okay, I ran the same scenario again, and here's what happened.

The streams began to lose their striping at about 7 seconds remaining. I let it continue through to the end anyway. It yielded 30g. 5g more than the previous. It also tasted oh-so-slightly weaker. Not really over-extracted. Just not as sweet. So I did the math. 60%. It's just a regular espresso. Still great!

So does this just mean that I did not tamp as hard as before? I suppose there is also the possibility that the grinder is holding on to some of the grounds. I keep forgetting to weigh the PF before and after grinding.

What do you all think?