Yeah, I'm not looking for a 'replacement' boiler for that old Visacrem VX automatic. I don't need a huge old machine like that, parts are scarce, and I assume nobody else needs one either. I'll be opting for a rebuild from a new frame up, or more precisely group down. Detached boiler. Group modified to accept thermosiphon heating - it's 5 lbs of brass, so gotta heat it. Old method was direct attachment for this head, but if I get a good thermosiphon setup I think we can keep the head heated fine. Of course that means some re-engineering of how the head ports work but it's just plugging one hole, carefully drilling another and attaching a little bit of head exhaust tubing for the 3-way valve outlet. But that's going to be another thread someday.
I like that 1/4 turn steam valve. Going to to be a really nice machine in the end. (Wish my parts machine had normal valves, but they use some weird tip valve. Flip a lever on the front of the machine, and that tips the nose of the valve to open it up for flow. Those may or may not make it to the final design.)
Posted Wed May 8, 2013, 10:48am Subject: Re: Next Mod: PID my Gaggia Classic
There is still a lot of performance tuning to do, but that's what I have to do next. The machine has been traveling with me to and from work the last few days (almost a week, I think) for surgery and I think it's tired and need a rest, so hardware/software improvements will be slow from this point.
I still have not been able to get the SD module running yet, then again, I haven't put too much effort into it. I'm more interested in the RTC replacement, but that's another 2-3 weeks out.
Here's an update on the PIDruino.
Yesterday was a short day for me, since with work and all, I had to take off a little early to audit/try out and enroll my 4yo daughter in Tae Kwon Do class. It was her first day and she was... disruptive... but so cute. Anyway, it was a short day and I basically only for got the steam plumbing done.
Last night was all software. Here is what was done. Keep in mind, my PIDruino has 5 digital buttons. - Button 1 (Power): Since delayed key presses are a little bit more tricky to detect, I did a shortcut and programmed only Power On (Wake) and Power Standby (Sleep). Well, obviously, Wake will bump the PID target temperature to (200F in my case), turn on the LCD backlight, change the button LED from blink to solid, and enable all high voltage accessories. Standby will do the opposite and set the target temperature to 150F. I could go lower, but this is comfortable. I believe I've set my Bunn tea brewer to 140F or 150F for standby mode. - Button 2 (Auto-Surf): Just as a temporary use of the Menu button, I programmed an auto-surf button. On demand, this will take readings of the TC and run the pump for about a second (which is a bit aggressive). I have to turn this down, since by the time the TC reads 200F, the pump is still going and I end up dropping to about 180F. I've set the target temp to 210F, and I'm still overshooting, so this is one of those performance tuning items on my list. This MAY end up being a post-lazyautomatic operation (on Button 4). - Button 3 (Steam): On demand, this button bumps up the target temperature for steam production. In my case, I've set it to 220F (for now), as the temps continue to raise to ~260F. Has anyone ever boiled milk (or other liquids) on the stove and when it reaches near boiling, the temperature rises exponentially? Well, I think this is what's happening in the boiler. It won't stop at 220F, so this value must be gauged and the over-boil temp must be accounted for. We certainly don't want to crack the boiler. I'll also have to implement a routine to add water into the boiler during the steam production mode so the boiler does not run dry and overheat the boiler. Things will go wrong when this happens, mostly drying out and cracking o-rings and such. I'll have a "calculated" value on the screen for boiler pressure later as a new feature so I can tell just about how much steam I have. - Button 4 (Lazy-Automatic brew): I have not set the advanced recipe routine yet, just a shot timer. I had it set to 25 seconds, but after the BIG PIPE I added to the steam plumbing, it takes a bit more time since it has to fill this pipe before any pressure can be built up, so I added another 5 seconds. I guess that's too long and the espresso went blonde. Easy enough to adjust but I'll eventually be adding this feature in the menu and storing it in the flash memory so I don't need to adjust it in the program. The goal is to not need my laptop to make coffee. :D - Button 5 (Manual brew): Just as it states: manual brew, which just replaces the stock rocker switch, just in a digital format. There's really nothing like manual control, as my wife would say. She said, "The coffee is... different... today." I told her "The new Lazy-Automatic made the coffee." She replied, "I knew something was different." Go figure.
Anyway, anyone attempting a full "espresso controller", not just PID, using an Arduino, here's a hint. I'd run into this while bench testing. You may assign routines to each button correctly but what happens when you press another button while one button is in-progress? You'll step all over that routine and the system will go nuts. So, alongside all the features mentioned, last night was also "Lockout" night. I don't have the machine here today so I can't post any pictures, but you'll see on my LCD that I have a "LOCKOUT" indicator. This locks out any and all buttons (except Power) while a routine is in progress. The button LED also flashes to let me know which button is active, the only one I can press, and that I need to turn it off at some point.
I'm going to buy some cheap coffee after work so I can do some performance testing. I'll probably go through a pound or more to get the numbers right, or close.
Posted Wed May 15, 2013, 9:52pm Subject: Re: Next Mod: PID my Gaggia Classic
Well, I got my new RTC's in today, but they don't work (at least the first one I opened, pack of 5). In haste, I may have connected it backwards, so I'll try again tomorrow or the next.
In the meanwhile, I did make a video but it was not impressive, and the face plate screen wasn't done so... I'll contemplate posting it. I did however silkscreen a screen and will mount it tonight so it'll have the sleek, contemporary look to it. Maybe I'll make a video after the screen is on.
I did more programming and tuning the last couple days. I was able to tune the steam button to periodically pump water into the boiler to keep the steam going. My duration may be too short since I'm getting moisture in my pitcher. My Auto-Surf function is working great now. It will overshoot about 5F, which I can adjust the offset to hit the target set point, but I'm thinking it is not a big issue, since it recovers from 5F extremely quickly and hovers around 202F (I've set my set point to 200F).
The tuning is quite good so far. I was trying to cool the boiler this morning so I could take it into the office for more work. At ~200F, I hit the brew button and it immediately drops to about 195F. In the past, it would drop to about 160F before I get tired and feel like the pump is being overworked and I unplug the machine and call it quits. This would take about 30-60 seconds. This morning, I had the button down for about 90 seconds and the darn thing was fighting me at 195F! I finally plug, opened the cap, and unplugged the heater connectors and tried again. About 60 seconds, later, I was down to about 80F and it was ok for travel. Sheesh...
FYI, I am able to maintain a 7F window during the brew cycle. Again, I have my set point to 200F. I have a 15 second pre-start heating time, then start my 25 second (+3 for steam wand fill) pull. Once the actual pull starts, the temp drops to about 195F and slowly rises to about 202F and the lazy-automatic ends the brew cycle. 7F doesn't seem so bad, given the stock Gaggia Classic with tstat setup will drop to about 165F from 210F! My coffee is no longer sour AND bitter. Just a tad bitter but not bad! The coffee has been bad lately with too firm of crema that don't stick too well... probably because I've been focusing too much on the hardware/software that the beans got old. Time to order some new beans! :D
I'll see about posting a video when I get the screen on.
Posted Thu May 16, 2013, 10:34am Subject: Re: Next Mod: PID my Gaggia Classic
This is "Powered On".
Of course, the illuminated areas are active areas, so the system only shows what buttons you can press in each mode. Most of the time, there is only one (maybe two active "functions" and the only one you can press will "blink".
RTC is still not working. I removed the RTC module since it wasn't doing anything but sucking a small amount of power.
"NO LOCKOUT" means the system is ready for a command and there are no active "interactive functions", although there are plenty of non-interactive functions going on.
The left column show from top to bottom: upper water temp (this is what we're most interested in), boiler/heating element temp (is what we try to keep under control to prevent too much overshooting), and heater power (this is normally a scale from 0-255, but I decided to convert it to %, since it is more human-friendly. It is also NOT voltage or even power (watts), but duty cycle - more accurately, "On-Time").
The 200.0 next to the 204.3F (current water temp) is the target set point.
Obviously, the 1.0 bar is a digital boiler pressure gauge. This is how I can regulate my steam pressure and automatically maintain it.
"Not Ready" means the water temp is either too hot (in this case) or too cold. I've coded my tolerance to ±2F.
"Shot 28" indicated shot-time. I have mine set to 28 seconds (which will count from 0-27 when the lazy-automatic button is pressed). My espresso normally goes blonde at around 25 seconds. The extra 3 seconds are to fill the newly installed steam plumbing, which is a 1/8 NPT pipe which takes about 3 seconds to fill (one of those things I'll have to fix).
I did the best I could with the graphics. I have a day job, so I had about 2-3 hours to design the graphics and take it to silkscreening. I handled the screen too early so the "Power" ink started rubbing off (before I even installed it last night).
So, graphics are as so: - Universal Power icon - Gears, for configuration or setup (it is my auto-surf function right now, until I work on the menu) - Steam, I'm not sure if you can make that out - Timed Brew, supposed to be a crema-stream with a clock in the back. I may have to redesign that. It looks like "Biohazard" - Manual Brew... I guess everyone can identify that
Posted Thu May 16, 2013, 11:25pm Subject: Re: Next Mod: PID my Gaggia Classic
Alright, I'm afraid I may turn into a YouTube-whore. Here is a 8 minute video of the PIDuino before a lot of tuning, calibration, and aesthetic touches.
I'm not much into talking through videos, well, this is my second "public" video anyhow, so watch the finger as I'm showing you what to pay attention to.
Of course, first is turning on the power, or backlight really. Then I run the pump until the water temp is below the set point. It takes a little while for the temp to get back to 200F. When it does, it overshoots, then I demonstrate the auto-surf function to bring it back down quickly. The current tuning (in the video) does a pretty decent job, but it is much better now.
Then to demonstrate the lazy-automatic button (fourth button), it's hard to make out but the shot time counts up to 27, starting at 0. In computer-talk, that would be 28 seconds. The PID function tries to equalize the temp so when the brew cycle is done, the heaters are still going, so it overshoots to like 240F or so. Then the auto-surf to get it back down to ~200F.
Then the steam demo. At this time, I hadn't really spent too much time tuning the steam button, so it didn't get too much steam pressure. It is now able to sustain 250F+ for as long as there is water in the reservoir.
That's really all. There have been many improvements to the software since this video was taken. I'll post them as I have them.
The music was not added in. It was actually playing in the background. I had no idea the mic on my Nikon D5100 would pick it up so well.
I messed up the puck, because the temp was wrong and I wanted to surf it, pulled the PF and realized... what the hell... the temp is wrong, the puck is messed up... and it's just a demo video. I wasn't gonna drink it.
It was old coffee beans anyway, about 2-3 weeks old. It did taste lousy anyway...
Posted Fri May 17, 2013, 10:08am Subject: Re: Next Mod: PID my Gaggia Classic
This is not something I'll be doing now, since my PIDuino is working pretty well, at least a lot better than stock, but during development, it's occurred that I did slightly under-spec the "brain".
From left to right: - The "imitation" Arduino Pro Mini is what I originally planned to use to keep the whole thing as compact as I could, but it turns out, it doesn't have enough GPIO to do all the things I wanted it to do. If you just want PID function, this is a good device, but my PIDuino turned out to be an espresso machine "controller", it wasn't gonna cut the cake.
- The "imitation" Maple Mini was never really an option, but it's somewhat in the same class. It's WAY overkill for even an EMC with it's 32-bit microprocessor running at 72MHz, but if anyone wanted to, I guess it would work. I purchased these for my 9x20 spindle retro modification, but... they didn't work. They failed to take new programs. Word of advise on these - "don't buy the imitation stuff". I buy the "cheap" stuff to experiment with and see if I like it. This one was a BIG fail. I haven't gotten these to work yet, so but I still need it for another project. I'll have to buy the real deal at some point.
- This one just came today. A "real deal" Arduino Micro. It has 20 pins of digital IO and 12 pins of analog IO. I haven't powered it up yet, but I'm sure it's fine. I've had nothing but good luck with the Arduino brand controllers and accessories (maybe that's why they cost more). Woohoo! It's got micro-USB... a little MORE modern.
- On the protoboard is the "eBay special, imitation" Arduino Nano, the same as what I have in the PIDuino. The first one was destroyed in a "drop test", and the second one is ticking away, keeping temps as we speak, so to speak. Like all the other Arduinos, it runs at 16MHz and this one has 14 pins of digital IO and 8 pins of analog IO. I just need 2 more GPIO and everything would be peachy... hence the search for the Arduino Micro.
The Micro is longer so I would have to re-cut the aluminum facing... so, that won't happen for a little bit, yet.
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