I bought this little Salda for $10 at a garage sale, knowing it would be a good little machine with a service and a few minor improvements.
 

As standard, single boiler machines including the Rancilio Silvia, Gaggia Classic, Lelit, Nemox, Imat, Quaha and others are perfectly capable of making good espresso though with a few downsides, one of which is a huge variance in boiler water temperature due to their very simple thermostats. This can be compensated for in a few ways, one popular option being to retrofit a PID controller to help regulate boiler temperature more precisely, which is one key ingredient to making consistently good espresso.

This is a rather expensive and complicated option (although PID hardware itself is not costly these days – it’s the installation and calibration that can be tricky), and a simpler, more cost-effective modification can be to simply fit a digital thermometer to the boiler giving the user a visual indication of the boiler temperature, which can then be used to time the start of the espresso extraction for the best results. This is known as Temperature Surfing.

Improvements included:

• Replacing the original Saeco-type pressurised portafilter and group collar with a 57mm non-pressurised Lelit type, with naked conversion
• Brew water pre-heating via a simple tube that wraps around the boiler to improve temperature stability
• Digital temperature display via thermocouple fitted to brass boiler
• Conversion to ball-joint steam wand including custom single-hole steam tip
• Brew pressure gauge fitted between 3-way solenoid and group outlet to read true extraction pressure
• Kill switch fitted to pump to enable low pressure pre-infusion
• Custom aluminium handles for steam valve / portafilter, custom Huon Pine matching tamper

I ended up taking things a bit further than I’d initially planned, but I reckon this is now the best little single boiler machine around, and makes killer shots with a bit of careful attention to the brewing temperature and pressure. As it’s so simple and small, this is the perfect machine to chuck in the boot with a hand grinder for a weekend away.

While most domestic and commercial espresso equipment on the market is capable of achieving excellent results, there are occasions where better performance can be gained from making a few simple internal modifications. Through monitoring how the machine is behaving, we’d be able to assess what, if anything, could be gained in terms of temperature stability at the group or other usability improvements eg. better steam pressure, quicker recovery time etc. If you’ve got something in mind, I can tell you whether it’s going to A. give you the result you want, and B. remain safe and cost effective.

In most cases, excessive group temperatures in traditional heat-exchanger machines can be controlled through the addition of a thermosyphon restrictor (a small disc with a precisely sized opening, placed into the heat exchanger) that is tuned to the particular temperature that you want to achieve. This allows you to lower the temperature at the group without losing steam pressure, and negating the need for a cooling flush. It’s a very simple but significant upgrade for most domestic E61-group machines that run hot – associated with burnt or bitter flavours in espresso and steam/spluttering from the group when the pump is activated.

For the ultimate temperature control, some machines may benefit from replacing stock thermostats or pressurestats with modern PID hardware. This often has a dual benefit in terms of easy temperature adjustability, and long term reliability as digital controllers and associated devices have no moving parts.

The list of possibilities are almost endless. If you’d like to improve your existing machine rather than upgrading, give me a call and we’ll see what can be done. Some suggestions to get you thinking:

• Swapping steam and hot water wand locations
• Upgrade to lever-activated steam valve or cool-touch wands
• Custom steam tips for more usable steaming
• Two-stage pre-infusion switch for semi-automatic solenoid groups
• Upgraded heating element control system incorporating solid state relays for greater reliability
• Adding auto-fill controllers to older manual fill machines
• Plumb-in conversions for tank machines