Hi,
I am getting consistently weird behavior while making espresso. My first shot of the day after a 30min warm-up is a normal flow 25g/30s and then the subsequent shots run much faster like 30-35g/20s. I have been consistently getting this behavior three days in a row and can't get to the bottom of it.

I am using fresh lightly roasted Red Brick by SQM and my grinder is vario. I was single dosing during these and grinding so fine that the vario clumps a bit, but now that I switched to using the hopper and timer I can't make the flow normal. It is as if the vario does not react to the micro slider at all. I am using naked PF, in-basket wdt and distribution is the same between shots. I have tried to manage the temperature of my HX (oscar) to the best of my abilities, but to my understanding, even temperature differences of few degrees do not cause such flow rate changes.

So what gives? Is it most likely a barista issue, a grinder consistency or adjustment issue or an espresso machine issue? I have not noticed this behavior before with darker roasts and I have kept my routine the same (even if fouled) lately.

Could the PF be a little moist after the first shot (I towel dry) and cause channeling?

I'd first verify that the weight of the doses was equal, to make sure that the dose-by-time is getting you consistent weights.

FinnLight wrote:Hi,
I am getting consistently weird behavior while making espresso. My first shot of the day after a 30min warm-up

I can't say your warm up period is short for sure, but I know that my own Oscar seems to be more evenly heated after 40 minutes. Would that make the difference in extraction times? I doubt it, but stranger things have happened with espresso.

Remember that on the Oscar first the boiler water is heated, that in turn heats the HX water and group. It takes quite a while for the group to come up to heat with the thermosyphon.

When you first bring the machine up for use do you run water through to group to aid in heating it up? If I'm trying to do that to speed up my first shot I'll do it with the portafilter/basket locked in to get everything good and hot. I also use a 10 second flush and minimum 4 second reheat for the first pull after a long idle time to get any superheated water out of the HX, but for warmup I'd give the reheat cycle a little more time.

^^Ah, but I was single-dosing when this started happening so yes I was weighing my doses.

I thought this was an issue with the vario, but I am not sure. When single-dosing with the vario I have understood that the burrs start grinding closer to each other at the beginning, then as more coffee gets ground the burrs are actually pushed a little bit further apart producing coarser grind and then again as the dose nears its end and the burrs start to clear the grind is a bit finer again. I have noticed this behavior before when I dialed in my grinder by single-dosing and then when happy with the settings and dose would go to hopper and timer-based use of the vario. I have always been forced to tighten the grind setting at least few notches. But what I am experiencing now is different. I am not touching the settings between the subsequent shots.

DanoM wrote:I can't say your warm up period is short for sure, but I know that my own Oscar seems to be more evenly heated after 40 minutes. Would that make the difference in extraction times? I doubt it, but stranger things have happened with espresso.

Remember that on the Oscar first the boiler water is heated, that in turn heats the HX water and group. It takes quite a while for the group to come up to heat with the thermosyphon.

When you first bring the machine up for use do you run water through to group to aid in heating it up? If I'm trying to do that to speed up my first shot I'll do it with the portafilter/basket locked in to get everything good and hot. I also use a 10 second flush and minimum 4 second reheat for the first pull after a long idle time to get any superheated water out of the HX, but for warmup I'd give the reheat cycle a little more time.

You are completely correct. I actually performed a warm-up test with and without warm-up flushes. I started the flushes after the boiler was up to pressure. The group-head temperature data looked following:

Time (mins):______ 0 _5 10 15 20 25 30 35 40 45 50 55 60
Without flushes (C):25 27 36 48 56 71 77 81 83 84 85 86 86
With flushes (C):___x __x _x 65 74 81 89 90 90 x x x x

So yes. Flushing speeds up the heating so that by the 30min mark you are good to go. I did 2-3 flushes during heating. And yesterday when we had guests the oscar had been on for several hours before I brewed the shots.

Is it possible there is old coffee stuck in the Vario when you start up and you're getting an extra chunk of it?

When I used to use electric to grind, I'd grind through a couple of beans at very coarse to knock out the old stuff before going back to a finer setting. The design of my electric (Baratza as well) seemed to contribute to build up.

It is as if the vario does not react to the micro slider at all.

If you want a grinder that will do what you want, and not lag behind in it's adjustments, you need something that isn't plastic. The vario is known for not responding immediately to changes especially in the espresso range with light roasts. You adjust finer, for instance, and it's the same- then a few shots later it's too fine, so you adjust coarser, etc. Eventually you get it right, but it takes a lot of beans. If you use the hopper, that change in bean height will compound the problem since a difference in weight changes the grind as well (except at +1/2 full or something like that), so keep single dosing.

The above reasons are why people upgrade to 64mm grinders, or titan conicals. My only advice is to learn to become "one" with the vario. You can also keep single dosing and when you adjust finer, go past where you want, and then back down. Also, fyi, some folks have reported baratza saying that the vario isn't designed for super light roasts.

Grind first load. Put it aside. Grind second load and use that first. Then use first load. This should identify if the problem if the grinder.

bostonbuzz wrote:The vario is known for not responding immediately to changes especially in the espresso range with light roasts. You adjust finer, for instance, and it's the same- then a few shots later it's too fine, so you adjust coarser, etc. Eventually you get it right, but it takes a lot of beans. If you use the hopper, that change in bean height will compound the problem since a difference in weight changes the grind as well (except at +1/2 full or something like that), so keep single dosing.

Thinking back, this sums up my espresso experience with the Vario extremely well. The grind quality was fine for what it was, but making adjustments was frustrating for exactly the reason you mention.

Randy G. wrote:Grind first load. Put it aside. Grind second load and use that first. Then use first load. This should identify if the problem if the grinder.

Great advice. I will try this next time I brew.

bostonbuzz wrote:The vario is known for not responding immediately to changes especially in the espresso range with light roasts. You adjust finer, for instance, and it's the same- then a few shots later it's too fine, so you adjust coarser, etc. Eventually you get it right, but it takes a lot of beans. If you use the hopper, that change in bean height will compound the problem since a difference in weight changes the grind as well (except at +1/2 full or something like that), so keep single dosing.

Bob_McBob wrote: Thinking back, this sums up my espresso experience with the Vario extremely well. The grind quality was fine for what it was, but making adjustments was frustrating for exactly the reason you mention.

My experience also. I was very pleased with the vario first, but now not so. The adjustment mechanism is complete crap. Also, with the PF attachment, controlling the distribution into the basket is difficult. I am sooo looking for an upgrade already...