Espresso Machine

 

My Ascaso’s Dream Up Modification

July 17, 2011

Recently I purchased an Ascaso Dream Up espresso machine as I enjoy the art and science behind how an espresso is pulled. 


Grind fineness, tamping force, and brew temperature are critical parameters to espresso brewing and they determine how good your shot will be.  Fineness of coffee powder can be achieved by using a good quality burr grinder such the Compak K-3 Touch.  Proper tamping can be achieved through practice.  Brew temperature on the Dream Up is controlled by a bimetallic strip thermostat which is designed to cut power to the water boiler when temperature reaches 100 degree Celsius.  The limitation with this type of thermostat is its responsiveness.  Good temperature control on the Dream Up is therefore challenging due to this inherent limitation.  Another concern is that the brew thermostat measures the temperature on top of boiler, but what is critical is the temperature at the grouphead, which can be a few degrees C lower than temperature at the boiler.  With a thermostat there is no mean for me to adjust the brew temperature on this machine, making fine tuning impossible.


One possible solution I found is to install a Proportional–Integral–Derivative (PID).  PID is used in some of the more expensive espresso machines.  Auber sells kits to retrofit Rancillo Silvia.  For the rest of us who are non Silvia users we are out of luck.  Or aren’t we?  I studied the internal design of the Silvia and compared it to my Dream Up and noticed that both machines are very similar to each other with 2 differences.  The first is the Silvia can dispense hot water and the Dream Up cannot.  The second is they have different schematics, making the instruction provided by Auber unusable for the Dream Up.   Beyond these differences both machines operate quite the same way internally.


After understanding the challenges associated with this modification I bought a retrofit kit from Auber.  This kit is designed for Silvia, so to install it inside the Dream Up requires changes in electrical wiring and mechanical mounting.  After a few days of sketching up the wiring diagram and verifying I gathered enough courage to start working.  The modification was a success!  After the installation I confirm that Auber’s PID works as intended on the Ascaso Dream Up.


Doing what I did will void my machine’s warranty, of course!    
















Picture above shows the main controller that comes with the kit.  Other items included in this kit are:

-Wires for installation.  All of them can be used on the Dream Up.

-Aluminum enclosure.

-Solid State Relay (SSR)

-RTD sensor to replace the thermostats.  I asked for the M4 screw-in type to suit my machine.

-White thermal compound.

-Cable ties.

-Instruction CD.

Solid State Relay (SSR).  This is to replace the two thermostats (for brew and steam functions) inside the Dream Up.

I drilled a hole on the metal plate next to steam knob and mount the SSR there.  This is the only location that I found to be most suitable as I only needed to drill one hole.

Another view of the SSR.

Screw to mount SSR to metal plate.

Top view of the boiler inside Dream Up.

RTD sensor in place of brew thermostat.
Steam thermostat used to locate here.  I removed it because it is not required in PID setup.

Here is how the controller is installed on top of my Dream Up.  My machine has no provision to mount the controller, so I pick a spot on top cover closer to the front.  I know mounting it there really ruins the classic look of the Dream Up, but functionality is more important than look to me.


Four holes have to be drilled on the top cover to accommodate the standoffs.  The standoffs are 28mm tall.  The boiler is below the PID controller, so I use a taller standoffs to minimize heat from the boiler from conducting to the controller.

Inside view of top cover.  I route the wires from the PID controller through a 5mm hole I drilled.

5mm hole on top cover for wires to pass through.  Both sides of the hole are countersunk to remove sharp edges.  
You don’t want the insulator on the wires to get cut, else nasty electrical shock could result.

Completed product!  The temperature on the PID is preset to 110 degree C.  This gives me about 96 degrees C at the grouphead of the machine.  I may need to fine tune it further.

Tamping Station

Good tamp is essential to proper extraction of espresso.  Experts say 30lb of pressure is required to yield good result.  Tamping is no doubt an important step in espresso pulling experience.  While I enjoy brewing my coffee I also can’t resist the temptation to do some work on my CNC mill.  What can be more rewarding than to machine a tamping station out of Polycarbonate material.  This tamping station provides a steady platform for the portafilter to sit on while I tamp, it also serves as a storage base when the tamper is not in use.

Output side of SSR.  These 4 wires will be connected to the wires for the brew and steam thermostats in the original Dream Up.

Photo above shows portafilter, aluminum tamper, and tamper station.

View showing upper profile of the tamping station.  The “Y” shape profile allows the portafilter to sit and remains in place.

Top view of tamping station.  Black colored object is an O-ring.  It is there to provide support to the tamper.

Apply some white thermal compound between the base of SSR and metal plate.

Schematics

Here are the schematics if you want to setup your own Ascaso Dream Up with an Auber PID.  The first diagram is the wiring diagram for stock machine.  The second diagram is what I have done to make my machine work with Auber’s PID.