this all has me wondering: as you say the common wisdom is that there is no point in having a PID on a lever.

On a Pavoni it looks like there is a point after all (beyond just looking fricken beautiful... in a techno geek way).

I have a Faema Lambro- and it has a small hole on the face (for viewing the Gas flame I guess)- I wanted to shove a PID in there just to take the machine into the 21st Century... but always figured it was pointless. But would it be? Seems like a great way to be able to regulate the boiler pressure and temp- not sure how relevant it would be to the group head temp but perhaps it could be worth a test?

Also is it safe? To mess around with the pressure and control it with PID?

Does anyone have an opinion?

sorrentinacoffee wrote:this all has me wondering: as you say the common wisdom is that there is no point in having a PID on a lever.

On a Pavoni it looks like there is a point after all (beyond just looking fricken beautiful... in a techno geek way).

I have a Faema Lambro- and it has a small hole on the face (for viewing the Gas flame I guess)- I wanted to shove a PID in there just to take the machine into the 21st Century... but always figured it was pointless. But would it be? Seems like a great way to be able to regulate the boiler pressure and temp- not sure how relevant it would be to the group head temp but perhaps it could be worth a test?

Also is it safe? To mess around with the pressure and control it with PID?

Does anyone have an opinion?

A lot depends on how stable the temperature of the machine is naturally. If there are big temperature swings, then a PID controller will make a big difference. If you already have a pressure stat or something that helps pin down the temperature of the machine, then a PID controller isn't going to have quite as noticeable impact on things.

Ray

Hi

Here is my PID control in LP PC-16





I bougth all the suf in http://www.dinicoinc.com/
The PID, the SSD relay and the thermocouple J type

It's provisional till the electronics store opens and I can go to buy some decent inox box, my idea is to put the LP over the inox box and ther install all the PID stuf something like the
http://topcoffeemachine.com/la-pavoni/page/3/

As I said in other tread Thanks Ray for the idea

Hope U like It

Very nice!

Ray

sorrentinacoffee wrote:Also is it safe? To mess around with the pressure and control it with PID?

Beyond the safety if dealing with high current electrical devices, which is related to the skill of the tinkerer, the question boils down to the inherent design safety of the pressurized vessel, and the potential for an overpressure explosion event.

I believe the safest way to PID a previously pressurestat controlled machine is to place the SSR in series with the pressurestat and set the pressurestat higher than you would nominally operate the machine, but still in the safe range. Then, if the PID program goes nuts or the SSR fails on, the machine reverts to pressure control, albeit at a higher temperature than your normal operation. There would still be the additional overtemp safety and overpressure safety.

sorrentinacoffee wrote:Also is it safe? To mess around with the pressure and control it with PID?



Beyond the safety if dealing with high current electrical devices, which is related to the skill of the tinkerer, the question boils down to the inherent design safety of the pressurized vessel, and the potential for an overpressure explosion event.

I believe the safest way to PID a previously pressurestat controlled machine is to place the SSR in series with the pressurestat and set the pressurestat higher than you would nominally operate the machine, but still in the safe range. Then, if the PID program goes nuts or the SSR fails on, the machine reverts to pressure control, albeit at a higher temperature than your normal operation. There would still be the additional overtemp safety and overpressure safety.

thanks Allon- this has me thinking. I have a Sama club machine (like Ponte Vecchio) I am restoring. I cannot find a rocker switch to replace the old one which is broken. The hole size is 38mmx20mm- larger than the more standard PV one. It looks to me like I could enlarge this hole and fit a PID into the machine... if I could run two temp probes off it - I could run one to control the boiler (inline with a p s-stat).... the other one I could run into the neck part of the sama group head- there is already a screw there from where they drilled the group to make it a thermosyhon connection. This probe would be read only- showing how the group head heats up- and how it behaves during a shot. I would need to drill out the screw that is there and tap a hole (the screw seems to have been permanenty screwed in somehow- the threads are already damaged as if someone tried to remove it. I would only want to touch the metal with the probe- so the hole has to be shallow- the smaller type probe Ray tested in this thread looks just perfect....

It may be quite useless but it seems like it'll be fun to watch the temp peak and fall during a shot as the water passes through the group neck...

Seems like this could be a great way to finish off my restoration- purely for the sake of it. I am doing this one as a hobby side project and want to go to town on the machine. I have already prepped the boiler and painted the chassis and cabinet...

But is a PID really worthwhile? It seems that the modern electronics will be the parts most likely to fail after the restoration...

The Sama does not have a high temp cutoff- or a low water level probe- as the later PV does. Should I add them as well? Or could a PID controller take on/cover those safety functions (is there a PID probe that is also a water probe and/or can the PID be set to stop the machine overheating)?

Ray: do you really, really think this is modification is totally worth it?

you will have to forgive me here: I really know nothing about the finer points of this technology and don't understand the technical details (I don't even know what an SSR is... but I do want one)...

Here is the Sama as it stands:

sorrentinacoffee wrote:Ray: do you really, really think this is modification is totally worth it?

On the La Pavoni that I had, yes, I think it was worth all the effort. My biggest complaint, originally, with the machine was that it was very difficult to control the temperature. As soon as I installed the PID controller, the consistency of the temperature (between shots) was drastically improved.

Originally, attempting to temperature surf the machine was maddening. I would pull 5 or 6 shots and half (or more) would be out of whack as far as the temperature.

Once I installed the PID controller, the temperature swing issue basically went away. All the shots were consistent (as far as the temperature went). I found that removing the temperature variable from the mix was very helpful as far as improving the shots. It also resulted in far fewer "sink shots" due to having the temperature drastically too high or too low.

There is still some temperature drop between the boiler and the group head, which can't really be controlled. However, having the PID controller keeping the boiler (and thus the overall machine) in line does seem to help keep there as well. I guess you could say that the biggest thing the PID controller does (in addition to regulating the boiler water temperature) is to keep the machine from over heating. For example, when I steam milk (which takes the PID controller out of contention during this time) and then flip back down to the "low" setting, where the PID controller takes over control, it takes about 5 minutes for the PID controller to bring the machine back down to the target temp. This is really helpful, because it not only regulates the boiler water temperature, but also the overall machine in effect.

I've also thought about using that smaller RTD sensor in order to monitor the temperature of the group head. I was thinking about buying an extra basket and then drilling that sensor into the bottom of the basket. This would allow me to use a 2nd PID controller (in a read-only fashion) to monitor the group head temperature during the shot.

As far as the reliability of the PID controller and the electronics: if you look back over this thread, you'll see there was a lot of talk about heat issues, etc. On my machine, I did install a heat shield (which helps a lot), but in the real world, I have had zero problems with the PID controller, or with the SSR (solid state relay). During testing the SSR on the bench, it never got above around 90 degrees. Of course, I pre-heat my machine on the "II" setting, which bypasses the SSR and the PID controller; as such, most of the heavy lifting of getting the machine up to temp doesn't involve the electronics. Once the machine is warmed up, then I turn the switch back down to "I", which hands control back over to the PID controller. From that point, the PID controller and SSR are just tasked with maintaining the temperature, which doesn't really take a lot of constant power via the SSR.

I use the La Pavoni every day to make espresso. It functions flawlessly and produces really nice shots. The milk steaming is fantastic and the PID controller keeps the machine running perfectly. I can leave the machine on for an hour or more and it keeps the boiler temperature to +/- .1 degree. With the adjustable pressure regulator (and the PID controller working together), the machine makes no noise on the counter. It just coasts along happily until you pull a shot. I do have to keep an eye on the water level, however, since I removed the over heating thing on the bottom of the boiler.

Anyway, to answer your question: yes, it's worth while. It made a big difference in my case and took the machine from being sort of a headache to use to being a joy to use. As soon as the PID controller was in the mix, I went from being able to only pull one drinkable shot in about 5 to pulling all drinkable shots one after the other. Removing the temperature swing issue made a big difference, even when you still take into account the issue of having some temperature drop between the boiler and the group head. Like I say, once the entire machine is up to temperature and the PID controller has everything stabilized, it seems that even that is not much of a factor any longer.

As far as a PID controller which will turn the machine off in the event of the temperature going too high (i.e. running out of water or something), I don't know off hand. You could probably check around though. I don't believe my PID controller has that feature, but I know that Auber makes another PID controller that is purpose built for espresso machines. I think it has a couple of extra features.

Anyway, if you have any other questions, feel free to ask or post here

Ray

RayJohns wrote:As far as a PID controller which will turn the machine off in the event of the temperature going too high (i.e. running out of water or something), I don't know off hand. You could probably check around though. I don't believe my PID controller has that feature, but I know that Auber makes another PID controller that is purpose built for espresso machines. I think it has a couple of extra features.

It depends on the PID controller. The controller runs a control loop - it feeds outputs (turning the boiler on and off) to achieve a desired input (the temperature). Some PID controllers have the ability to enter an alarm state based on inputs (water level?) or upon noticing a loss of control (the inputs don't make sense based on the outputs, such as a runaway temperature). With some units it would be possible to configure the alarm state to turn off the boiler, and maybe even sound an audible alarm.

Here is the PID controller I used:

http://www.auberins.com/index.php?main_...ucts_id=14

It does say that, when you use the SSR circuit, the relay circuit can be used for an alarm. I'm not sure what triggers the alarm, but you might be able to wire the alarm into a relay which would kill the power to the boiler perhaps.

There's a link at the bottom of the page above for the manual. I think there is an alarm temperature setting, but I will have to read through the manual again to see how it works.

Ray

That was an EPIC project! and an awesome read. There was so much information in there my head is spinning a bit....I read it in one sitting... that milling is beautiful (in all cases). Man, I gotta go have some espresso and think about all of this...... Great Vision and excecution of a mod! It is so juxpostion in that the lever machine is just so manual, and then to add a PID which is so not manual, Excellent..... Congratulations!