I'm a new member but long time follower of the HB forum and I'm compelled to post now because I'm being driven crazy by my new Vivald II/ Cimbali Junior set-up. So far I've used two and a half pounds of coffee and I'm not any closer to better espresso. I'm looking for help to diagnose where my problem lies.

Currently I am using the Cimbali Jr. with the PVC throat extension and the hopper removed to prevent any binding. On the machine I have a naked portafilter without the retaining spring so I can leave the portafilter in the group while grinding and dosing.

Right now my procedure is to: pull a warm up shot into a cup; grind a few grams of coffee to clear the chute; empty the doser of old coffee; grind fresh coffee (1-2 days post roast) and dose 15 grams (measured after dosing); Weiss distribution with paper clip; tamp; remove portafilter drop in basket and pull shot.

I've tried to control for all the variables, but using this technique I've been getting wild changes in shot times over three pulls. Grinding enough for three shots gives me 20 seconds of variability without changing anything and I don't know what else to check.

I'm hoping I can call on the wealth of knowledge here to help me think of something that could be causing this.

there are a lot of possible options but what comes to mind first is that you might want to search for "popcorn effect"

On the Cimbali Junior, you need to keep at least 1/4 pound of beans in the hopper. The grinder is not at all suitable for grinding single doses or for operation with a near empty hopper, since it has almost no throat to hold the beans going into the burrs. If you were low on beans, the popcorning effect Chris mentioned would be vicious.

Thanks for all the great help! I've been working on this for weeks and in a matter of hours I feel like I've made more progress.

Considering I'm only going to be grinding enough beans for a few shots I was wondering if there was a way to modify the Cimbali Jr. to make it more amenable to this use.

I've seen a lot of grinder modifications that use tampers to weight the beans. If I could find a way to combine the PVC adapter I'm using to make the beginnings of a throat and something to weight the beans would this help alleviate the popcorn effect?

If so, is there anything I should consider besides hitting the spinning lower burr with the weight?

It's a project, and you'd have an easier time ebaying the Cimbali and buying a Mazzer, Macap or Compak, which work this way without any mods. You had the bad luck getting just about the worst possible grinder for this way of doing things.

No matter what the grinder, if you set the the grind for single portions, do only single portions, since there's always a bit of the popcorn effect.

I_am_JohnGalt wrote:I'm a new member but long time follower of the HB forum ....

You're obsessing over an exaggerated concept of "freshness" and ruining your coffee. The CO2 bubbling out of your coffee is spoiling the extraction. For espresso, week-old coffee is almost always better than one or two day old coffee. Intelligentsia lets theirs sit for 7 to 9 days before brewing. Heather Perry at Coffee Klatch waits a similar time, if not longer, in her competitions. Over at Supreme Bean, Phil Hand recommends opening up the bag and letting air mix in for 3 or 4 days, if you can't wait a week.

Load up that hopper, my friend. Your espresso will improve immensely.

When I picked up a pound of the 2008 USBC Competition blend at Klatch last week, they told me that they wait 14 days after roast on that particular blend.

Marshall wrote:You're obsessing over an exaggerated concept of "freshness" and ruining your coffee. The CO2 bubbling out of your coffee is spoiling the extraction. For espresso, week-old coffee is almost always better than one or two day old coffee. Intelligentsia lets theirs sit for 7 to 9 days before brewing. Heather Perry at Coffee Klatch waits a similar time, if not longer, in her competitions. Over at Supreme Bean, Phil Hand recommends opening up the bag and letting air mix in for 3 or 4 days, if you can't wait a week.

Load up that hopper, my friend. Your espresso will improve immensely.

I agree.. I think waiting a little longer then 1 or 2 days post rost will improve things very much.

One time.. i fell behind on roasting. So.. I roasted a larger then normal batch, planning on using it 2 days post roast and on. Man oh man, I could not get a single consistent/good shot with the beans 2 days post roast. Once they hit 4 days.. things became much more consistent.

My absolute minimum for espresso use, is 3 days. on average, I wait 4 or 5. There is an exception, which is Yemen beans, which I dont touch for at least 8 days. Also, if i buy already roasted beans, and the roaster suggests a certain wait time before pulling shots, then Ill do that.

But.. isn't it great that one our PROBLEMS is beans that are TOO fresh to use? Sometimes my diamond shoes dont fit either.

Jeff

Marshall wrote:For espresso, week-old coffee is almost always better than one or two day old coffee.

I would disagree.
Just because a number of SoCal roasters have blends that respond in this manner doesn't make it universal.
I can list a huge number of coffees that fade dramatically at 6 days out of roast.

Each coffee has its own sweet spot.
Treat each coffee as unique and respect each coffee as individual and you'll get better results.


Beyond that... his consistency issues are unlikely to be related to "overly fresh" coffee.

So, I seem to be circling around consistent shots, but I haven't gotten there yet. This morning I pulled three shots 1:06, 32, 33s in that order.

I built a PVC contraption that has a weighted piston to press down on the coffee to try and address the popcorn effect. I only allowed the coffee to degas for two days, but I got anxious to try some shots this morning.

I don't know if I should count my first shot as an outlier(maybe I'm not putting enough fresh coffee through in the morning to clear the chute) or if I'm still having the same problems. I'm inclined to think that my inconsistency before was a confluence of all the factors mentioned in the previous posts and I'm on the right track now, but I'm not sure.

Do most people leave beans in their hopper to allow the beans to degas and keep pressure on the burrs or is that a solution specific to my grinder? If it's the latter does my PVC solution seem to be an adaquate compromise or is there a variable I'm not accounting for besides pressure on the beans?

piston and Flange


assembled


in grinder

A Tamper is about ¾ of a pound and I don't think a tamper as a weight is a good idea on a Jr.

In normal operation, there is a very small bean mass above the burrs. A very few ounces at most.

In my Macap MXK, I've found that a 4oz weight seems optimal in the 'mini hopper'

Why not just throw a half lb to a lb into the hopper and see what you get then?
My guess is that this will solve your consistency issues far more effectively than all the PVC tubing in Long Beach (and there is a lot).