Update on the JB Weld for the drip tray leak: worked like a charm. I'll be checking the solenoid shortly.

Thanks!

Update: removing and rinsing the inside of the solenoid valve (sliding magnet as well as cylindrical housing) did not help the chattering. I multimeter'd the leads of the solenoid coil (with autofill enabled: disconnected level probe and removed coil from valve body to prevent boiler from actually filling) and here's what I got:

Resistance: 154Ohm
Voltage: 118V AC

My multimeter doesn't do inductance, unfortunately. Do the coil's vitals look ok?

Going back to my thermofuse problem - does anyone know if there's a way to test if a fuse is working? If I turn on my electric stove burner and touch it with the remaining part of the fuse thermocouple (the broken part), can I expect to see the fuse pop if the temperature of the stove burner is above 165C? (Yes, if I attempt this method, I will take precautions to avoid setting the kitchen on fire.) I ask this because I am still considering soldering the fuse back to the lead sticking out of the boiler.

Thanks!

Hello Dan (thanks for the parts orders)
I tried in the past with a thermocouple next to a thermostat probe and with the heat from my heat gun
I was able to get them to trip pretty close to the temp settings they should had.
so I was pretty close to be accurate there,
NOW
unofficially
I do not want to tell you to by-pass the thermostat and is not normally something that I will suggest to anybody,
BUT considering that is a very old type and like we talked in the past the upgrade to new style etc etc was too expensive
and I assume you already explore many other options

think of this:
if the water line is clean,the pump/ motor the inlet solenoid valve is opening every time it needs to,
the pressurestat is new and so is the safety boiler valve
come to the rest of the conclusion

Stefano, thanks for the reply. Right now I am using the machine as you... err... don't recommend . The thermofuse is just hanging by the somewhat rigid wires that are bolted to the heating element. I would prefer to avoid drilling into the element or boiler to mount a new (smaller) style thermofuse, hence my preference to keep this one. Your last sentence is absolutely right about the good water, pump, pressurestat, and solenoids, and if I were not considering a PID setup, I would leave it as is. However, I have heard concerns that an SSR relay may get stuck on (sending current to the element) so I would like to have a failsafe (in addition to leaving the pressurestat connected and enabled). I'll post my ideas/plans for an Arduino-based all-in-one Elektra brain setup once I have them more collected.

stefano65 wrote:(thanks for the parts orders)

And thank you for the speedy shipping. My "spare gasket emergency kit" arrived today.

In other news, I have line pressure preinfusion! It's better than a hack - it exploits the shaky construction of the big red shot button. The button, as you can guess, completes two otherwise separate circuits: connecting 120VAC line power to the group solenoid and to the pump. Luckily, the button actuates one piece at a time - carefully pressing the button half way will only turn on the solenoid, and pressing the button all the way will turn on the pump.

Since you don't want to drill (which I can't really blame you about) for a safety temp switch.

If there is room you may be able to use a stainless steel hose clamp to clamp the safety switch to the end of the boiler. Worst case, it falls off and does nothing useful when you need it (I guess truly worst is it short out something).

As to a totally software controlled Espresso machine.... I'd certainly put the mechanical safeties in there. After all, I do software for a living and I *KNOW* it's not bug free. Heck even if your code is perfect, there could be a compiler bug. That said, there is room for a reasonably priced replacement board that can control an espresso machine that is easily setup and programmed. I do remember a board member in Europe posting about his board (it looked beautiful) but it wasn't inexpensive.

Arduino base controlled board ideas:
2 thermocouple inputs (or RTD) or more (boiler & group head)
1 SSR controller (perhaps two: one steam, one boiler, or a group head heater)
1 motor controller (on/off), or perhaps stepper drive a pump motor?
1 stepper controller for driving pressure valve for pressure profiling
1 LCD panel for I/O
5 (or so) buttons (or touch screen)
Precision timer (so you can automatically start a pre-warm cycle!)
USB for updates (or SD card)
Pizo Alarm (water sensor inputs?)
etc.

Mark

Mark - I am aiming for the Arduino approach. I started a separate thread for that discussion. The mechanical safeties are a must - that's why I want to keep my pressurestat and install the safety thermostat properly before proceeding.

So here's my take on line-pressure preinfusion: the lever geek in me absolutely loves it, but otherwise I'll need more time and shots to figure out the difference. For some reason, preinfusing until the bottom of the basket beads up is... fun. And I have no idea why. (It's probably the lever geek talking again.)

No real progress, but with the help of the local Swagelok office and Nicholas (shadowfox), I have my probe setup (for PID):



Here is a list of the parts from my Swagelok invoice, with the part description in parentheses and my own notes after each dash:

1. B-400-3 (Tee) - self explanatory
2. SS-200-R-4BT (Reducer / Bore thru) - the top stainless steel piece that actually holds the probe
3. B-4-TA-1-6 (Tube adapter)
4. B-4-TA-7-6 (Tube adapter)
5. B-6-A-6RS (3/8 FNPT x 3/8 MISOP (RS)) - the fitting that screws into the boiler, sealed to the boiler with the copper washer that I had used for the safety valve

Note that I ordered everything in brass (the "B") except for item 2, which was not available bored through in brass. The difference according to the salesman is that the stainless steel versions of the other fittings cost about twice as much. My total was around $30.

The Swagelok salesman (who is a fittings magician, by the way), gave me a teflon ferrule for the compression fitting at the top to hold the probe itself, because, he said, it would hold a seal for the pressure I need (up to 30psi, I told him) and it will not permanently/destructively fuse to the probe itself. He also advised me on a rule of thumb for these compression fittings: finger tight followed by one and a quarter turn (in his words: "You start at 12 o'clock, one rotation back to 12 o'clock, then go to 3 o'clock and stop").

The only problem is that the pressure release safety valve seems to be leaking in this position, though I didn't think that its direction had anything to do with how well it holds (there's a spring in there, of course). Does this indicate a failing safety valve?

Update: I ordered a new safety valve and reassembled the tee. With enough teflon tape around the valve threads, my probe setup is leak-free and probe temperature reading confirmed by my multimeter. Now all I have to do is order an Arduino, design and order a PC board, and order the parts. My order of 4 Auber 25A SSRs and heatsinks already arrived.