Here's my situation: I'm currently weighing whether to completely replace my setup (Expobar Office Lever, Baratza Vario) with what I might consider my personal endgame (DE1 Pro, P64), or to simply hot rod my current setup to extend its usable lifespan (hyperalign and Forte-fy the Vario; add some toys to the Expobar). Hence a question about some of the aftermarket accessories you can buy for the E61 group head.

I'd like to get a group thermometer because, as my Expobar is a HX machine, temp management is a major challenge and I've always lamented my lack of visibility into brew temps (even approx. temp would do).

At the same time, I'd like to add a flow control device because I really want to play with different profiles that lend themselves to lighter roasts--something I haven't explored very much of, and would like to.

Here's the problem: the thermometer and the pressure gauge from the flow control kit would both compete over the single port on the E61 group. As I think temp management is more important than profiling on an E61, that means that if I went for FC I'd want to use the kit without the pressure gauge. But before pulling the trigger on a pretty expensive gamble I thought I'd ask the experts.

Is the flow control kit useful without the pressure gauge? My gut says yes, especially with the addition of a smart scale, because regardless of pressure, the end goal of the FC kit is to modulate the flow rate of coffee into the cup (using pressure to do so). Couldn't I do just as well using a smart scale (measuring flow rate) instead of a manometer (measuring approx. group pressure) to guide my inputs to the flow paddle? Am I thinking about that right?

Edited to add: I'm not super handy with tools aside from wrenches and screwdrivers, and don't have access to the right power tools, so solutions like tapping new ports into my group head or drilling & routing gauges through my machine's casing aren't options for me--I just need to work with what I've got.

A scale-based solution is too slow to respond to try to close a feedback loop manually. The scale itself has about a half-second of lag, There's a half-second of lag in trying to estimate flow rate from weight to even 0.1 g/s. Pick a less-optimal algorithm and your scale or app may be seconds behind the actual flow rate. When you're pulling shots in the 15-20 second, start-to-finish range, it's over before the scale has a chance to show much of anything valuable.

I find the pressure in the basket very important with controlling basket fill and soak. My machine is looking to stop filling when the pressure hits a certain level ("basket is full"), hold zero flow into the basket until the pressure drops ("coffee is soaked"), and then ramp up. Many people are either already using machines with less than 8-bar extraction pressures (lever machines, for example) or choosing to extract at lower pressures. As the pressure gauge is well under a second in its response, it is valuable in monitoring these phases.

Both pressure/flow and temperature are important to extract light roasts well. You've hit the big problem with using an HX for light-roast espresso.

Jeff wrote:You've hit the big problem with using an HX for light-roast espresso.

Man, if only flow control had been more of a thing when I picked this machine up in 2014...

Anyway, hypothetical question. In my shoes (guy who prefers light roasts in brewed coffee, currently pulling medium roast espresso but curious about light & SO, aging equipment, upgrade-itis etc. etc.) --- what direction would you lean? Optimize for temperature control, flow control, OR just punt and get off the HX wagon entirely before I sink too much more money into it?

At this point I'd consider myself a very advanced user of an e61 flow control device. I use a double boiler and would never consider a HX machine for many reasons, this being one of them.

Jeff is spot on about the importance of fast feedback and the steps a well extracted shot should go through. For me I start a shot by fillling at a higher flow rate for a fixed period to introduce the correct amount of water required to fully saturate the puck. Then I'm stopping the flow and aiming for a very slight pressure decrease settling at a fixed pressure until I get drips in the cup. At this point I open the flow back up and focus solely on pressure as flow is no longer a reasonable way to think about a fully saturated portafilter. All of this is based on sit second timing and REQUIRES a group mounted pressure gauge.

I think a lot of people would be well served by finding the class of coffees that work with their grinder and machine and suit their tastes. Then seek out a roaster or roasters that produce better-than-average examples of that on a regular basis.

Putting $5 a week into higher-quality coffee is probably better in the cup than throwing $250 a year in toys on the counter and then often into the junk alternative tools drawer

One cheat that I've used with the Strada for ultra-slow preinfusion, despite the grouphead-mounted gauge, is adjusting the flow rate before locking in the portafilter. That is, I use the Strada MP handle much like a flow control device, slowing the water flow to a trickle. Then I lock in the portafilter, let the pump run for ~15 seconds, and once the bottom of the cup is covered, increase to full pressure.

Dan's cheat can be well translated to the E61.

I've been using the Bianca for about three years now. When the shot is flowing, I don't look at the pressure gauge, but at the flow itself; so not having the gauge is no hardship. But I do use it when there is no flow, during the preinfusion. I leave the paddle on full flow, watch the gauge unti it starts to rise, then turn the gauge so the pressure stops rising at 2.5 bar. Then I wait for the first few drops, and reopen the paddle for the flow part of the shot.

So what would I do if I had no gauge?

First, I'd find the exact postion, just ahead of the a full shutdown, that lets creates a steady drip from the group head with no PF. This will be my preinfuse position. I'd start the shot with the paddle full open -- after 4 seconds (rotary pump) to 6 seconds (vibe pump) I'd shut the paddle to this preinfuse position, and wait for the first drops. Then I'd operate the paddle to visually control the flow rate (I like to gradually decrease the flow, YMMV).