This is something I recently put together, an "Espresso Flow Meter", which tells me how fast my espresso is filling the cup.

Would this be useful to you?

It might be useful to those who want to see the real flow rate when making espresso, or when calibrating their grinds. Different flow rates yield very different flavors, and I could see a "recipe" for a given roast wanting to take flow rate into account.

Has anyone made or sold something like this before?

I know of the Gicar flow meter (https://www.espressoparts.com/gicar-1-4 ... -flowmeter), we have one, and some high end espresso machines use it, but I don't know of any espresso machine displaying the actual flow rate, and it'd be flow-before-the-puck, which is a different piece of information.

I've done the "low tech" version of this by watching the scale with a stopwatch. The Acaia Lunar allows you to deduce the flow rate by analyzing the shot weight over time graph it spits out for you, but who wants to spend over $200 on a scale?

What scale are you using out of curiosity? Did you find one with an api or did you hack together your own with a load cell?

I would love a scale with an api available to gather metrics for this sort of stuff or even to mod or otherwise automate other devices, such as autostopping a shot when a desired brew ratio is reached or a programmable needle valve to regulate a specific flow. Yes I can make my own with a microcontroller but I think this sort of thing should be doable in a production package for $50 bucks or less, and would be very popular with us techies.

dominico wrote:I've done the "low tech" version of this by watching the scale with a stopwatch.

That's exactly what we've been doing too, but it's nice to know when your flow rate changes, which it normally does over the course of a shot.

Rao would like to see if this software could detect channeling (short bursts of faster flow) by charting and analyzing weights more often. I'm going to do some experiments to see if that's possible. The scale we're using refreshes its weight 10x per second, so it's something I can experiment with.

dominico wrote:What scale are you using out of curiosity? Did you find one with an api or did you hack together your own with a load cell?

There is an extreme lack of competition among 0.1g accurate bluetooth scales, and believe me, I've been looking!

I found a fairly nice scale made by five self-employed young engineers, and it is marketed exclusively to the Taiwanese pour over coffee market. They've made a nice Android/iOS app that helps train you to do appropriate flow rate when making pour over coffee. It's only in Chinese, though <sigh>.



They don't have an Android api (yet) but their BLE protocol was "bluetooth connect, then receive weight 10x per second as 4 bytes, you're done". Keeping it simple, I love it. The scale stays on as long as you're bluetooth connected (your app is running) and powers off when you turn off your phone.

I think Acaia make a nice product, but they have an API that uses DRM to prevent you from working with it directly (not through their API), and they pulled their API some time ago (their small scales have no current API), and they also wanted me to sign some legalese in order to let me use their scale with my app. DRM and legal agreements plus high prices, me no like, so I've used other scales. They've said that they've "paused" their API and will bring it back, so maybe if they get rid of the DRM and legal requirements, I will be able to support them with my software.

Non-Bluetooth, I really like the Brewista scale, and that's what we're using for our Doser product http://decentespresso.com/doser

dominico wrote:I would love a scale with an api available to gather metrics for this sort of stuff

We should talk!

I'm going to be importing and selling this Taiwanese scale soon. The Bluetooth spec is dead simple, and we will have Android and iOS toolkits for it. It's not super cheap (current shipped price is US$130) but it is *open* and available for buying now, so it does what I need. Maybe it'll do what you need too.

dominico wrote:or even to mod or otherwise automate other devices, such as autostopping a shot when a desired brew ratio is reached

As it happens, I'm working on just that feature, as a retrofit to existing machines.

I've got a Bluetooth solenoid wired into our Mazzer Robur grinder, that stops the motor when the weight hits our desired point. You can see that modded Robur and the (beta) Android software talking to it (with an Acaia scale) in this video:
That exact same setup will give you gravimetric dosing on an existing espresso machine, as long as you can figure out where to wire in our on/off solenoid to stop the shot.

I'm working on developing that gravimetric-retrofit feature with this Taiwanese scale, but it's a bit on the large side to roll out as a product. They're working on rev 2 of their scale, which will be smaller. Brewista has also indicated that they might add USB to their scales in the future, and I'd definitely support them with that.

dominico wrote:or a programmable needle valve to regulate a specific flow.

We're totally on the same page.

We're working on the highly accurate (manual) needle valve portafilter side of things, which you can see here:


and we're thinking about a bluetooth controlled stepper motor for it. That is a long way off, though, because we need to ship our espresso machine first.

It looks interesting/promising. In the video you use an E61 group, stopping that automatically would be tricky I think. You can stop the motor, but that would not mean that you stop the shot.

I have a Vesuvius. That has a timer (and info about the pressure). It would be nice if the flowrate gets synchronized with that as well.

tohenk2 wrote:It looks interesting/promising. In the video you use an E61 group, stopping that automatically would be tricky I think. You can stop the motor, but that would not mean that you stop the shot. I have a Vesuvius. That has a timer (and info about the pressure). It would be nice if the flowrate gets synchronized with that as well.

Agreed, my E61 is very mechanical, so I'd stop the pump, but that would likely be good enough. However, the solenoid idea would definitely work better on more modern machines where start/stop is a button.

Like I said, I have a Vesuvius. That has pressure profiles and a timer that start when I put the grouphead lever up. It would be nice to measure the output from the go. I now have around 8 seconds before the espresso hits the cup (can be way longer, but this is my present favourite) - and I find this time to be important as well as the flowrate after that. So, omitting that time/pressure is - well ... incomplete data.
If I would use say a Lunar or Brewista scale I can subtract times to deduce this 8 second pre-infusion, but it would be way more neat if this is done automatically (and recorded in an app like in your video, maybe with a graphic representation). And even more so if the pressure profile gets matched with an output flow-rate.

I've been doing flow rate monitoring and control (ie, automated flow profiling) using a scale built into the drip tray for years. As is documented in many places (ie, pretty hard to miss). Only significant problem is that espresso flow is a somewhat noisy signal.

IMO, a paddle wheel flow sensor could also do a good job (with firmware that accurately records pulse edge times).

jonr wrote:I've been doing flow rate monitoring and control (ie, automated flow profiling) using a scale built into the drip tray for years. As is documented in many places (ie, pretty hard to miss). Only significant problem is that espresso flow is a somewhat noisy signal.

Jon, is it the case that the weighing signal itself is noisy, or is it that the flow rate is extremely variable and always changing?

How often are you charting the weight change?

I ask, because Rao's tasked me with seeing if I can detect channeling by tracking quick flow changes, and I'm wondering if you've been able to.

Insofar as the original question is concerned, are you thinking of incorporating it into your machine? If so, then a prior art search would be in order to check for previous patents. My guess is that Super Autos would have to use some sort of metering system.

Encoder(vane) type flow meters are now used in most dosing(auto) machines. There were other technologies used, such as the various adjustable rods in the Cimbali Junior, but most have been abandoned. Remember that anything put into the path of the flow from the portafilter will also effect the flow itself, and I wonder what effect pushing brewed espresso through a spinning encoder would have on the crema and coffee overall, as it would act as a mixer.

cuppajoe wrote:Insofar as the original question is concerned, are you thinking of incorporating it into your machine? If so, then a prior art search would be in order to check for previous patents. My guess is that Super Autos would have to use some sort of metering system.

What I'm discussing here is making/selling a scale (weight) based flow meter, that could be used on any existing espresso machine (put the scale under your cup), not something that requires modding an existing machine, nor anything that is in the liquid path.