Fabbing an espresso machine

Need help with equipment usage or want to share your latest discovery?
Trimethylpurine
Posts: 135
Joined: 9 years ago

#1: Post by Trimethylpurine »

tl;dr

Thinking about fabbing an espresso machine. Want to know the acceptable ranges for these variables for the water hitting the puck in such a machine:

Volume

Temperature

Pressure

Time of shot

The long bit

I have lived in Chengdu, Sichuan, western China for 6 years and in August I will be moving to Zhuhai, right next door to Shenzhen, the worlds factory city. A friend of mine is trying to redesign the computer keyboard for programmers and is getting parts fabbed to order from various places in china and putting them together in various iterations. He challenged me to do the same for a coffee machine.

I have a La Pavoni Pro on order, but it will take a few weeks to get here, or maybe more. I spent the last two days gorging on watching people use, misuse, disassemble, assemble and mod La Pavoni's on youtube until I am satiated. This morning I work up and had a nice lay in in bed, and thought about what such a coffee machine would be like, and what things would be desirable. I also imagined that it might have a very steampunk flavor.

After looking at steampunk images online (google image search steampunk machines) it seems a natural. So, brass, copper exterior, but with dial gauges. It seems a natural for a coffee machine.

So, I thought a series of levers to allow the user to set the following:

Water shot volume
Water shot temp
Time of shot.

Then the machine would read these, use a hidden computer controller to get the desired volume of correct temperature water in the grouphead, and then use some exposed cogged wheels (very steampunk) to drive a piston (La Pavoni like) at the correct speed to get that water through the puck in the desired time.

If there was a sensor that could then determine pressure in the grouphead it would then report that back to the user allowing them to adjust grind, volume of coffee and tamp pressure to get that pressure into the window they wanted.

Don't have the mechanism in mind yet for getting cogs to drive the piston, but it feels close, and if such an assembly can generate enough pressure for the job it seems to me that the feedback from the turning wheels to the PID will help it fine tune the speed of the motor driving that setup.

T
LMWDP #520 Trimethylpurine

User avatar
drgary
Team HB
Posts: 14348
Joined: 14 years ago

#2: Post by drgary »

Or ...

Go the other way. Read the many threads here from La Pavoni and Olympia Express Cremina owners. Make it ridiculously simple like the early La Pavoni machines. Overbuild the quality so it doesn't flex when you pull the lever. Use quality metals and materials throughout. Include a group thermometer so people can get better temperature control. This isn't very different than the Chinese roasters we're getting, overbuilt, simple and at times analog, or the Orphan Espresso grinders that are now being mass produced but way overbuilt with high quality grind capability at relatively low prices.

Building the Ultimate La Pavoni Europiccola

Adding Thermometry to a La Pavoni Europiccola
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

jmc
Posts: 160
Joined: 16 years ago

#3: Post by jmc »

Have a look at the Gaggia rack and pinion from their lever.

https://www.espressoparts.com/parts/esp ... levergroup

It should get you started,
John

User avatar
drgary
Team HB
Posts: 14348
Joined: 14 years ago

#4: Post by drgary »

That Gaggia's a good suggestion. In the early days of espresso, different piston designs competed before the Italians settled on spring-loaded pistons cocked by levers for their commercial machines. Before the spring-loaded lever, there was one that was geared, I believe. The earliest versions of the Elektra Microcasa a Leva home machine had a ratcheted tooth design instead of a spring. I'm writing this to say that if you focus too much on mechanical era alternatives to a spring-loaded or manual lever, you will probably re-learn the lessons of early design failures.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!