*gloop*

 

Espresso machine software testing

 Testing a mostly-functional espresso machine gui.  Somewhat Decent inspired.  While I don't have an interface for creating espresso profiles from within the gui, I can write arbitrary espresso profiles/state machines in python which is pretty powerful.  Testing with the Puck Simulator.

The profile in the video does the following:

• Cycle water through the tank at 2 mL/s until the water and the group head get up to temperature (I cheated this in the video and turned off heater power)
• Flow water through the group head to the drip tray at 2 mL/s for 2 seconds to purge the air from the group.
• Block off the drip tray, flow to the group at 2 mL/s until the pressure reaches 6 bars.
• Run at a flat 6 bars until the shot weight (estimated from the pump speed/pressure/flow curve since I don't have a built-in scale yet) reaches 32 grams.
• Open the valve between the drip tray and group head to rapidly purge pressure (so it doesn't keep dripping)
• Reset to the beginning and wait for input.

Adjustable Puck Simulator

Needle valve + basket with the bottom cut out + aluminum "puck" with an o-ring = adjustable coffee puck simulator.

First Shot

 It works!  Super janky right now but all the pieces work:

Espresso Machine Group Head Machining

 

 The click at 0:41 is very satisfying

Questionable workholding stack:

Fancy "morphed spiral" profiling toolpath came out well:

Inlet and outlet visible

With fittings, shower screen and seal installed, and portafilter locked in.

Proper blog post on the way

Gear Pump Closed Loop Pressure Control

 

Using a leftover pendulum motor controller, Moog brushless motor scavenged from the Media Lab years ago, and gear pump from ebay to play with closed-loop pressure control.  Pressure plotted on the computer screen (and shown on the gauge), pressure setpoint stepped up and down, and a needle valve used as a variable load.

Internals of the gear pump:  Food-grade, stainless body with PEEK/CF gears and bushings:

Inaugural Photo Dump: 5 Axis Mill At Work

2 parts in one operation, for a dial thermometer holder on the espresso machine grouphead.