I initially wanted to wait for the completed version of my mod to be on video but have now seen that Reiss is doing the exact same thing but utilizes a (IMO not so nice looking) hardware display and buttons. I am talking, of course, about the preinfusion setting.
Last time I wanted to change the preinfusion pressure on the LR I was a bit annoyed having to open the machine and check the pressure with a hand made portafilter manometer. So instead I wrote an App and a bit of software which can control the preinfusion pressure using an Arduino Nano and an industrial grade pressure sensor.
Since I read some people also complaining about the noise the pressurestat from the boiler makes, I also added a function to set the lower and upper boiler pressures which will also be measured by an industrial grade pressure sensor and controlled by a SSR relais for the heater (noiseless).
The upgrade can be done by only applying one mod to either the boiler or the preinfusion pressure or by applying both.
I did not yet install the hardware (still waiting for a smaller power supply in the mail), but added it to my Gaggia Classic Coffee test machine. In future there will also be a PID version for most "normal" espresso machines. In the case of the LR, I am not sure if PID would be necessary since the system will respond very slowly to a change in temperature and thus the heater gets longer breaks when controlled in a pressure range.
Here an image of the finished app, connections are already tested and working:
Although I want to separate something fun and relaxing like making espresso from all the technological stuff like smartphones and displays in general I think the way to go is an App to have precise control of all settings while keeping the clean and hassle free look of a classic espresso machine like the LR. Also this project could easily be expanded and updated via the App store (e.g. adding a timer to turn the machine on/off, automatic wait for a time to preinfuse and then beep, record times, taste protocolls, connect to a scale, ...)
For now it has these two functions and saves them to the internal chip. So when you want to play around you can and when you just want an espresso you do not have to worrry about anything.
If you (Reiss) are interested in my approach, I would gladly work with you. Otherwise I am looking forward to your finished solution :)
If I may report here - this is not directly Londinium related - but the prototype of the app is done with a spare espresso machine. When some more parts arrive I will apply this mod to the LR, then without the buttons so you won't be able to see the difference.
@Reiss, please let me know if it is not ok for me to post this in the Londinium forum, since you are working on something similar right now.
that said we will not be incorporating the ability to remotely adjust the pressure transducer in the LR
on your own machine you have the freedom to configure and develop it as you wish, but as a merchant i have more constraints
in particular i am uncomfortable asking customers to use a third party device to operate my machines, and secondly there is the issue of support; i do not want to become the first port of call for all my customers' iPhone and Samsung connectivity issues
if you need another example, it is the same logic that led me to decide not to offer dual fuel LONDINIUM machines, even though there is a significant commercial opportunity to do so; i decided they would simply be too difficult to properly support remotely
so my offering will not be as sophisticated as what you have built, but it will be stable and robust and i am confident that i will be able to continue to support my customer base better than any of my competitors, and that is central to the business model
I wanted to post a short update on my project. If you are wondering why it is taking me so long to finish: No, it is not that complicated to build and it will be even easier to apply the mod once everything is worked out. Since I am on a budget (like with all my projects) I am sourcing the hardware from outside my country. Sadly, they first sent me the wrong pressure transducers which had an error of approx. 0.5 bar at 110 °C (ranging from 0 to 150 psi). Add the remaining errors applicable to the signal path and it will be hard to set a pressure of 0.8 bar on the machine with fast heat up time and constant range. An offset would change the result to a good pressure range but will either stop the machine from heating up quickly or blow up the boiler (haha, I know there is savety).
The one I got after that was actually excellent. It was ranging from 0 to 30 psi and would have had a maximum error of around 0.1 bar at brewing temperature. I am still not sure why, but this sensor broke after I left the machine on for about 4 hours. My guess would be that the elements which are moved by the pressure within the transducer didn't like being under pressure, heated over 100 °C (even with this temp. being in the specs as it was rated up to 125 °C), sitting in steam and getting a current run through. Maybe it oxidized or something. First it seemed to be stuck, reading a high pressure all the time, then it had an offset of one bar constantly. During my ongoing search I noticed that even some 100+ € pressure transducers are not meant to be used in steam.
It is actually kind of ridiculous how hard it is to find a fitting transducer which isn't 500 € a pop and which can handle this kind of environment. After an extended search I now finally got one which seems very promising from the specs sheet. It should arrive this week and I will hopefully have time on the weekend to install it into the machine and adapt the code and hardware to it.
I am writing this post not only to ramble but also for you to see that even the smallest things can be a huge pain in the butt when dealing with these type of mods. You need knowledge of many different fields and the patience to find the errors if some occur (and they will). If you prefer a nice, complete solution, I would recommend Reiss's pressure adjuster since his version will probably be very robust. If someone is interested in my mod, I would gladly share the information on parts needed, wiring and the compiled code (not the source code) with you. We can also discuss potential changes and I would try to help you with problems but my time is very limited so it would be best for you to be prepared.
Btw.: currently there is no iPhone version, but if enough people are interested in it, I would program one as well (probably around Q1 2019).
Thanks for your feedback Joshua, it is appreciated!
So on Friday the new branded pressure transducers arrived and I switched both, the one for the boiler which was not working and the one for the preinfusion transducer, just to be save. Of course they sent me a wrong article again. This type of sensor measures the pressure in the medium against a preset pressure encased within the metal body of the transducer. Normally you would get a vented one which is at atmospheric pressure und they tell you the day and location when it was produced/vented so you could deduce the internal pressure with atmospheric changes at different days (not needed for this application) etc. Anyhow, my machine now has to subtract one bar to be at zero.
I am happy to report that the machine was running for more than 27 hours with the panels on (hotter electronics) and everything is well. I noticed that the boiler pressure can be set even more precise by two decimal places with the manometer and pressure transducer being precise enough to notice the difference. The program(s) are already changed to accompany that and only need a few tests before being the ‘official’ version.
There also is a separate offset available in the app, one for each transducer to negate potential sensor offsets at the higher working temperature. This was really meant for the Chinese sensors and I did not see any need to set an offset with the new transducers. But if you were to have a different reading on the manometer then set in the app, you could just set it as offset and forget about it since all readings will be automatically adapted then.
Changes to the machine I noticed so far are:
No more clicking of the Sirai pressure stat (duh!)
Bluetooth can go through a steel casing (phew ;))
The pump is set to about 4.7 bar, probably because the original pressure stat can only adjust a more limited range, so why not have this as additional safety for the pump. You should be able to adjust the maximum pump pressure with a screw from the bottom of the machine.
I wouldn’t necessarily change the pump pressure since it should be used for preinfusion and a preinfusion of > 4.5 bar is called an extraction on some machines.
If you want to pump at 9 bar, get a pump machine.
Of course you can always try it at your own risk.
The pump sometimes (especially at higher PI pressures) turns on when you turn on the cold machine. This is because the pressure to the PI/heating cycle is partly lost during downtime and then restored. If you, like me, enjoy a very quiet home and are bothered by the noise when the machine turns on in the morning, you could disable or better yet, automatically set the pump to 0.5 or 1 bar for the first 45 minutes, so it will be on very shortly. After 45 min heatup time the user defined PI pressure is used again.
I am not sure if the closed heating loop works better under pressure or if any amount of water is drained when turned off for too long, so I guess it wouldn’t hurt to keep it slightly pressurized. Also, it still can occur that the boiler is filled which would result in a longer pump noise.
When using the PI on the coffee, the pump may ‘stutter’ since it tries to keep the pressure at a constant level. SSRs are very fast, so in the EU you can turn the pump on/off 60 times a second. I am not sure yet if this could be a problem for the pump electronic but I think from a technical standpoint it should be fine in the long run. Maybe some people might react nervously when hearing their 300 € pump go ‘bapapapaparararawpa’. As Reiss already said in his news-post for his PI setter, this could be eliminated by a preset pressure range with the user setpoint in the middle. I don’t see the necessity at the moment; this functionality could be easily added with an update.
The machine also restores pressure to the cycle during runtime. I noticed it before the mod when the pump would turn on for a second or two. Now it will turn on more frequently (once an hour maybe?) but for a fraction of a second. You barely notice it. This could also be updated away by the above mentioned range.
Btw. It is not possible to get a live pressure reading during the extraction. When you move the lever (being pulled down completely) up until the pump is shut off, you are in the position in which the PI/water cycle is shut off from the brew group. From this lever position on up the backend pressure transducer is shut off from the extraction.
Overall I am very happy with my mod. Changing the PI pressure is fun to try but the machine can be enjoyed as simple object without buttons and dials as well. The newly gained silence with only the sound of boiling water when heating is almost therapeutic ;)
I think anyone with the will to do this can apply the mod to his machine. You should know how to solder, though, which really isn’t that hard. A rough estimation would be around one day to solder, remove stuff from the machine, add new stuff to the machine, test and have an espresso. When you need to buy the pressure transducers at MSRP, everything together will cost you around 350 € (~100 € to 500 €). This also depends on how much you already have lying around (cable shoes, soldering wire, wire, thermal paste, …). Higher quality SSRs would also add another 100 €, gettings the Arduino in a local store adds another 18 € etc.
Most needed parts come in larger volume, so I am thinking about making a few kits with presoldered parts etc. The actual work on the machine then includes:
Screwing out existing pressure stats and screwing in new ones
Changing some cables
Ziptying everything into place
If someone has genuine interest, I can also write a manual with pictures to aid you as well as a parts list. I am not taking responsibility if you get hurt or break anything!
I will follow up this post with a video soon. For now here are some pictures I took during the build process:
First version with old transducers, still a bit messy.
I enabled comments in the documents in case anyone wants to participate. I decided to go through the code/setup with the first person attempting this mod so we can check that the code and everything is correct in the manual(s). After that I will upload the compiled code and a manual how to apply it to the Arduino.
The manual is written as precise as possible and additionally has an image guide on all parts and connections. The original pressurestat can now also be reused as additional safety feature to shut off the system. This is especially nice for people who like to turn on the machine while sleeping or being not home (yet) without having to worry.
congratulations, well done on making it happen, you've done a great job
as a side note if you run the boiler much above 1.0 bar the thermosiphon will flash boil when you pull a shot, causing the thermosiphon to stall, and then the group temperature becomes erratic, with erratic extraction following. the higher the pressure in the pre-infusion circuit the more likely it is that flash boiling will occur when the shot is pulled
furthermore, movements in the boiler pressure only produce tiny movements in the brew temperature
by elevating the pre-infusion pressure instead you have the ability to significantly raise the brew temperature (& brew volume) by blowing the water out of the heat exchanger (at a temperature of around 125C) and into the brew chamber so much faster (due to the higher pressure) that it arrives at the puck much hotter, as the group has less time to suck the heat out of the water
my suggestion to all users of our LR/1/2/3 machines is to keep the boiler pressure at 1.0 bar and flex the pre-infusion pressure instead; that is the big discovery if you like in terms of making a lever machine being able to obtain good results from all roasts, dark, medium, or light whilst maintaining a thermally stable system