Here is a pictorial journey through the process:|
Click on any picture for a full sized view.
Here she is, she's led a tough life, but has served me well.
The Boiler and Group, notice the sludge buildup, yuck! That would be "MY" shortcoming there!
All laid out nice and neat after being disassembled.
Modification to the drip pan. I welded a 1/4" pipe nipple to it, drilled a corresponding hole in the frame, and attached some blue silicon tubing which runs out the back of the machine and down to a 5 gallon water bottle. Better than emptying the drip pan every day (or forgetting to)!
Stripped the old black paint off the frame and powder coated it blue to match my office decor.
Added a solenoid valve hooked up to the household water supply, eliminating the need for the bulky reservoir. No more manual refilling! Used 1/4" nylon tubing from the water supply to the "in" port, and reinforced food grade silicon tubing on the "out" port to match the pump fitting.
Here is the boiler and group all cleaned up with new gaskets and an adjustable OPV installed.
Now to mount the electronics. An Idec SmartRelay which is really a mini PLC, 2 SCRS (in retrospect I could have gotten by with just one), a 24vdc power supply, all mounted on DIN Rail with some terminal blocks to make connections easy. Got plenty of space since I don't need the reservoir anymore!
I insulated the boiler to help stabilize the temp better and to cut down on heat that the electronics would be exposed to.
Wired everything up. Threw out the original wiring and designed a schematic with new circuits of my own.
Wired in new buttons, a PID controller, and a pressure gauge into the front panel.
Top button UP = Auto shot of timed 4bar pre-infusion and timed 9bar infusion.
Top button DOWN = High pressure water, useful to extend a shot if I have the grind too fine.
Middle button UP = low pressure water (no pump) which is useful for topping off a cup with water.
Middle button DOWN = High Pressure water with 3-way valve closed, i.e. out of the steam wand.
Bottom button turns on the steam mode, upon turning it off the boiler automatically refills.
The orange lamp is no longer linked to the heater, it is now a "Safety" indicator that flashes whenever any type of Auto function is active.
Programed the SmartRelay to give me the feature set I want
The switches on the left are for manual override of all of the functions.
W=water solenoid, P= Pump, 3= 3-way valve, H=heat, B=Backflush program, and N= Stop everything even if in auto mode.
After experimentation I arrived at a 5 second pre-infusion, this is where the solenoid opens and allows a regulated water flow of 4bar.
Then the pump turns on for 23 seconds which delivers a 2oz shot at 9bar.
The Refill parameter will open the 3-way valve, then turns the water solenoid and pump on for 10 seconds
after the steam button is turned from on to off, this refills the boiler after steaming.
(Caution must be excercised as steam and hot water will come out of the group head)
Used my own homemade SCACE device to calibrate everything.
I auto-tuned the PID to achieve +/- 1 degree f, and adjusted the OPV so that the pressure is dead on the money!
10 months and 1170+ pulls later and she is working perfectly!
I use a 21g portafilter with 19-20g depending on the bean, weighed of course! With a 200 degree boiler, and a timed shot of 23 seconds at 9bar, after a 5 second low pressure pre-infusion, I achieve a 2oz shot. The remaining variables are tamp pressure (of which I am fairly consistent by now) and grind. Lady Silvia is still sensitive to grind so if my shot is short or long all I do is adjust the grind a little. I did modify the Rockey grinder to become "step-less" so that grind adjustments are infinite and more precise. Steaming is very quick, hotter than stock, very consistent, and works really well, but I rarely use it. Not many steamed milk drinks get made in my house. Dont get me started on the French Vanilla creamer that my SO uses, but she likes it, thats all that counts!
The result equals an awesome double shot with a rich crema, no channeling if I tamp right, and no blonding if I have the grind right.