Hi,

gear:
Vibiemme Domobar Super
Mazzer Mini

I am trying to dial the system in. I have read: http://www.home-barista.com/forum...p-guide-t3113.html

Doesn't seem to be helping much. The machine was running a boiler pressure of 1.5 so I lowered that to 1.1-1.2 range (not sure how accurate that gauge is or if I should have lowered it? the manual said it should be 1.1). When trying 14 grams (all tamping is 30lbs) the shots are too fast and the puck is sloppy. It takes a dose of slightly below the line in the basket to get what looks like a decent solid puck (this seems to be about 16grams), however my last 4 attempts the machine just chokes with that much coffee. I was increasing grind size each time but ran out of coffee, i think i did 4 clicks and it just kept on choking. Eventually would I have found the right grind or is there just too much coffee in the basket? Maybe the grind is right and a hard tamp makes it choke. (head spinning) Any coffee further down than slightly under the basket line leaves a wet sloppy puck on top but maybe that is ok? What about less coffee and lighter tamp? I don't want to waste any more until i get a few pointers. I have also been doing a flush what i think is about 10secs past flash boil and about a 15sec recovery as a starting point. I seem to be in this loop of shots shooting out or choking and no variation in between hits that magic 25-30sec time. The closest i got was 15 second shot or a choked shot. I need to try a new system, thanks for any help!

jeffg wrote:... lots and lots of questions ...

I'll briefly cover your questions, but let's focus on the choke versus gusher problem. Have you checked the brew pressure? I ask because a batch of Vibiemme Domobar Supers shipped with the wrong OPV spring, which lead to erratic brew pressures. Randy posted a picture of the two side by side:

Randy G. wrote:

The new spring, on the left, is much heavier than the original that I removed. The difference can be seen here, and compressing them between index finger and thumb reveals a great difference in compression force as well, with the new one being far stiffer.

<snip>

If you think that you have an OPV problem and suffer from erratic brew pressure, take a look at your spring and compare it to the photo above. I highly recommend replacing the old, thinner spring with the 'newer' heavier one. Contact Jim at 1st-Line for availability.

Now onto your questions...

• Q. Should I have lowered boiler pressure to 1.1? A. Yes.
  
• Q. Decent solid puck seems to be about 16 grams? A. Yes, at around 16 grams the puck will expand enough to press against the dispersion screen, but the puck appearance is not important (interest in such matters is commonly referred to as "puckology").
  
• Q. Is there just too much coffee in the basket? A. Adjusting the grind, you can put as much as 18-19 grams or as little as 12-14 grams for a double, though most suggest around 14-16 grams as a good start.
  
• Q. Maybe the grind is right and a hard tamp makes it choke? A. Maybe if you stand on it, but otherwise, no.
  
• Q. Slightly under the basket line leaves a wet sloppy puck on top but maybe that is ok? A. The puck may press up against the dispersion screen when it expands, but a little extra head clearance works well for your machine, if you grind fine enough.
  
• Q. What about less coffee and lighter tamp? A. Keep the coffee the same, keep the tamp the same. I tamp around 30 pounds, but the precise value is not as important as consistency.
  
• Q. I have also been doing a flush what i think is about 10secs past flash boil and about a 15sec recovery as a starting point. A. This is covered in Dave's review of the Vibiemme.

jeffg wrote:I seem to be in this loop of shots shooting out or choking and no variation in between hits that magic 25-30sec time. The closest i got was 15 second shot or a choked shot. I need to try a new system, thanks for any help!

As a point of comparison, I've been practicing with lower dosages (14 grams). That's well below the basket ridge when tamped and the top of the puck will have some puddles. The Mini grinder settings is about 8 notches finer than the arrow pointing towards me on the factory "start here" sticker. Don't be insulted, but do check that you're turning it the right way. Finer = counter-clockwise, coarser = clockwise. It's easy to misinterpret the arrows.

Once you have found the correct setting, the majority of coffees will be within ± 2 notches at the same weight. As a general guide, if I see a complete gusher because of a grind setting error, I move it 4 notches finer. A fast pour? Move around 2 notches. From there it's minor tweaks of less than a notch. If it chokes completely as in ZERO flow, at least 4 notches coarser. If the pour is very slow almost to the point of stalling, go 2-3 notches coarser. The thread Just starting out, grinder setting advice? offers more suggestions (e.g., how to "feel" if the grind setting is right).

You didn't mention if you have a 0.1 gram accuracy scale handy. If you're learning, it's worth having one to eliminate dosage variance and they go for less than $20 on eBay, shipping included. Volume measures also work, though they require more careful dosing technique. As a guide, if you don't settle the grounds while dosing, a level strike off of the grounds will be around 14 grams. A tap midway through dosing will add around 2-3 grams, but that varies widely depending on who is doing the dosing and tapping.

jeffg wrote:I need to try a new system, thanks for any help!

The site's FAQs and Favorites Digest includes recommended reading. If you're new, it's mandatory reading.

Finally, let me end with a recommendation about posing questions in the forum. I've noticed that rambling posts with lots of questions tend to languish. I imagine readers say to themselves, "OMG, I'd like to help this guy, but where do I start?" Next time try to narrow your query, you're more likely to attract responses from a wider audience.

Dan, can't thank you enough. Just the kind of info I was needing. I'll let you know how I go.

Thanks again!